Friday, October 31, 2014

The monophonic 270 watt Double barreled Amplifier

This amplifier is the monophonic 270 watt Double barreled Amplifier. For the original article, I specified plus and minus 85 V dc power supply voltages. The voltage can be increased to about 93 V to obtain a power rating of 300 W. The amplifier can be built either as a stereophonic or a monoponic unit. My original amps were mono units because the heat sinks, transformer, and filter caps that I used were too large for a stereo amp.

The circuit described on this page is a modification of the original Double Barreled Amplifier. The circuit has been simplified somewhat. The circuit board layout is smaller and much more compact. The driver transistors now mount on the circuit board instead of on external heat sinks. And the circuit has the feedforward compensation that I describe for the Low TIM Amplifier.

If you build this amplifier, you must keep the wiring between the heat sinks and the circuit boards as short as possible if you dont want oscillation problems.

When you test the circuit boards before connecting the power transistors, temporarily connect a 10 ohm resistor in series with a 0.1 ufd capacitor from the loudspeaker output to the power supply ground.
The Circuit Boards

I do not have circuit boards for the Double Barrelled Amplifier. If you wish to build it, you must make your own. Two drawings show the parts layout on the board, one with circuit traces and one without. These are scaled by a factor of 1.5. The other shows the circuit traces only. All layout views are from the component side of the board. You must flip the layout for the foil traces over to obtain the solder side view. The circuit board measures 4 inches by 6 inches. To my knowledge, there are no errors in the layout. If you decide to use it, you should carefully check it for errors because I could have easily made a mistake.

I do not recommend that you make the circuit boards unless you have experience in doing it. A source of materials for making your own printed circuits can be found here. I have been told that their "Press and Peel Blue" product (not the wet stuff they sell) can be used to successfully make boards with traces as narrow as 0.01 inch. The smallest traces on the amplifier layout are 0.03 inch wide. The PnP Blue product is basically a transfer medium that allows you to transfer the toner image from a laser printer directly onto bare copper clad board and then etch it in FeCl3 (ferric chloride).

After you etch the board, the copper should be cleaned with steel wool, lightly coated with solder flux, and then "tinned" with a soldering iron and rosin core solder. Do not use a commercial tinning solution that you dip the board into. It is almost impossible to solder a board that is tinned with one of these products because they corrode very quickly. When you drill the board, you should use the correct size drill bit for the pads. The hole diameters I recommend are: small pads - 0.032 inch, medium pads - 0.040 inch, large pads - 0.059 inch, mounting holes - 0.125 inch. If you do not use a sharp drill bit, you can pull the pads off the board when you drill it.

Circuit Description

If you compare the Double Barreled circuit to the Low TIM circuit, you will see a lot of similarity between the two. Indeed, there is a Low TIM Amplifier embedded in the Double Barreled Amplifier. The major difference between the two is that transistors are added in series with those in the Low TIM circuit to form the Double Barreled circuit. By doing this, the voltage across the transistors is decreased so that the power supply voltage can be increased for higher output power.

Basically, the circuit description for the Low TIM Amplifier also applies to the Double Barreled Amplifier. The major difference between the two is the addition of transistors Q22 through Q31. Q22 is connected as a common base stage at the output of Q12. The two transistors form a cascode stage. The base of Q22 connects to the junction of R52 and R54. These two resistors are equal and are connected as a voltage divider between the loudspeaker output and the positive rail. This forces the base voltage of Q22 to float half way between the loudspeaker output voltage and the positive power supply rail. Similarly, Q13 and Q23 form a cascode stage. R53 and R55 force the base of Q23 to float half way between the loudspeaker output voltage and the negative power supply rail. The addition of Q22 and Q23 cause the collector to emitter voltages of Q12 and Q13 to be approximately one-half of what the voltages would be without Q22 and Q23.

Transistors Q24 and Q25 connect in series with the pre-driver transistors Q14 and Q15. The base of Q24 floats half way between the output voltage and the positive rail. The base of Q25 floats half way between the output voltage and the negative rail. The addition of Q24 and Q25 cause the voltages across Q14 and Q15 to be approximately one-half of what they would be without Q24 and Q25. Similarly, transistors Q26 through Q31 cause the voltages across Q16 through Q21 to be approximately one-half of what they would be without Q26 through Q31. By connecting the transistors in series in this way, the rail voltages can be increased for higher output power.

The basic construction details of the Low TIM Amplifier also apply to the Double Barreled Amplifier. There are two short circuit jumper wires that must be soldered on the circuit board. These are marked with a J on the layout. In addition, you must solder a short circuit jumper in place of C6B if you use a non-polar capacitor for C6A. This is explained in the parts list for the Low TIM Amplifier. Because there are eight output transistors, two main heat sinks per channel are required. Q18, Q20, Q28, and Q30 should be mounted on one and Q19, Q21, Q29, and Q31 on the other. Resistors R61 through R64 and wires connecting the collectors of Q18 and Q20 and the collectors of Q19 and Q21 mount on the heat sinks. These connect between lugs on the transistor sockets. The four bias diodes D1 through D4 can be mounted on either heat sink. It is not necessary to divide the diodes between the two heat sinks because both heat sinks will operate at the same temperature. I recommend setting the voltage across Q7, i.e. the voltage between the collectors of Q22 and Q23, so that that amplifier is biased at 120 mA. This will give the same quiescent power dissipation per heat sink as in the Low TIM Amplifier.

Testing the Circuit Boards

After you solder the parts to the circuit board, it is tested using the same procedure specified for the Low TIM circuit board. First, you must solder the short circuit jumper across Q7 and you must solder the 100 ohm 1/4 W resistors from the loudspeaker output to the emitters of Q16 and Q17. If you dont have a bench power supply that puts out plus and minus 85 to 93 V dc, you can test the circuit board at a lower voltage. I would prefer test voltages of at least plus and minus 50 V dc. An option is to connect bench power supplies in series to obtain the plus and minus 85 to 93 V dc. I have routinely connected two 40 V Hewlett Packard power supplies in series with the positive and negative outputs of a Hewlett Packard 50 V dual power supply, and I have never had any problems. To protect the circuit boards, you might want to put a 100 ohm 1/4 W resistor in series with the plus and minus power supply leads for the tests. The current drawn by the circuit should be low enough so that the voltage drop across these resistors is less than 1 V if nothing is wrong on the circuit board. There are 2 ground wires from the circuit board. Both must be connected when testing the boards.

I cant stress how important it is to be careful in testing a circuit board. Even simple errors can cause the loss of many expensive transistors. I always use current limited bench power supplies to test a circuit board before and after connecting the power transistors. I also bias an amplifier using current limited power supplies in place of the amplifier power supply. When I initially power up an amplifier with its own power supply, I always use a Variac variable transformer to slowly increase the ac input voltage from 0 to 120 V rms while observing the amplifier output on an oscilloscope with a sine wave input signal. If I see anything wrong on the oscilloscope, I turn the Variac to zero and try to diagnose the problem using the bench power supply. I never use a load on the amplifier for these tests.

Parts List

With the following exceptions, the parts for the Double Barreled Amplifier are the same as for the Low TIM Amplifier.
Capacitors

C10, C11 - 15 pF mica
C13, C14 - 100 uFd 100 V radial electrolytic
C21, C22 - 47 uFd 100 V radial electrolytic
C26, C27 - 270 pF mica
C28 - 0.01 uFd 250 V film

Transistors

Q1, Q2, Q5, Q7, Q9, Q10 - MPS8099 or MPSA06
Q3, Q4, Q6, Q8, Q11 - MPS8599 or MPSA56
Q23, Q24 - 2N3439
Q22, Q25 - 2N5415
Q26 - MJE15030
Q27 - MJE15031
Q28, Q30 - MJ15003
Q29, Q31 - MJ15004

Diodes

D5, D6 - 1N4934 fast recovery rectifier
D13 through D16 - 1N5250B 20 volt zener diode

Resistors

R13, R14 - 5.6 kohm 1 watt (This value is for 85 V power supplies. For other power supply voltages, the formula is on the Parts List page for the Leach Amp.)
R28, R29 - 200 ohm 1/4 watt
R30, R31 - 3.9 kohm 1 watt
R37 through R40 - 470 ohm 1/4 watt
R41 through R44 - 10 ohm 1/2 watt (changed 6/27/00)
R52 through R55 - 6.2 kohm 1 watt
R56 through R59 - 10 ohm 1/2 watt (changed 6/27/00)
R60 - 39 ohm 1/4 watt
R61 through R64 - 0.33 ohm 5 watt. These 4 resistors are mounted on the heat sinks between solder lugs on the power transistor sockets. The wires that connect the collectors of Q18 and Q20 and the collectors of Q19 and Q21 are also soldered between the lugs on the sockets. Keep all leads as short as possible and use insulation stripped from hookup wire around the bare leads of the resistors.
R65, R66 - 300 ohm 1/4 watt
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Dual 3v White LED Flasher and Dual 1v5 White LED Flasher


This circuit alternately flashes 2 white LEDs, on a 3v supply and produces a really bright flash. The circuit produces a voltage above 5v if the LED isnt in circuit however the LED limits the voltage to its characteristic
voltage of three.2v to 3.6v.   The circuit takes concerning 2mA and is actually a voltage-doubler (voltage incrementer) arrangement.

The 1k charges the 100u and therefore the diode drops zero.6v to prevent the LED from setting out to illuminate on 3v. When a transistor conducts, the collector pulls the 100u down towards the 0v rail and therefore the negative of the electro is actually concerning 2v below the 0v rail. The LED sees 3v + 2v and illuminates terribly brightly when the voltage reaches about 3.4v.  All the energy within the electro is pumped into the LED to supply a really bright flash.

DUAL 1v5 WHITE LED FLASHER
This circuit alternately flashes 2 white LEDs, on a 1.5v supply and produces a really bright flash. The circuit
produces a voltage of concerning 25v when the LEDs dont seem to be connected, however the LEDs scale back this as they need a characteristic voltage-drop across them after they are illuminated. dont use a offer voltage above one.5v.

The circuit takes concerning 10mA. The transformer consists of thirty turns of terribly fine wire on a 1.6mm slug 6mm long, however any ferrite bead or slug will be used. the amount of turns isnt crucial. The 1n is very important and using the other worth or connecting it to the positive line can increase the provision current.
Using LEDs apart from white can alter the flash-rate considerably and each LEDs should be identical color.


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Thursday, October 30, 2014

Outdoor LED Solar Lights Circuit Schematic

This Outdoor LED Solar Garden Lights project is a hobby circuit of an automatic garden light using a LDR and 6V/5W solar panel. During day time, the internal rechargeable 6 Volt SLA battery receives charging current from the connected solar panel through polarity protection diode D9 and current limiting resistor R10. If ambient light is normal, transistor T1 is reverse biased by IC1 (LM555). Here IC1 is wired as a medium current inverting line driver, switched by an encapsulated light detector (10mm LDR). Multi-turn trimpot P1 sets the detection sensitivity. When ambient light dims, transistor T1 turns on to drive the white LED string (D1-D8). Now this lamp load at the output of T1 energizes. Resistors R1-R8 limits the operating current of the LEDs. When the ambient light level restores, circuit returns to its idle state and light(s) switched off by the circuit.

Outdoor LED Solar Lights Circuit Schematic


 
Outdoor
Outdoor Garden Solar Lights Circuit Diagram

Assemble the Outdoor Solar Lights circuit on a general purpose PCB and enclose the whole assembly in a transparent plastic box. Drill suitable holes on the top of the enclosure to mount the mini solar panel (SP1) and the light sensor (LDR), and in front for fitting power switch (S1) and the sensitivity controller (P1). Fix the battery inside the cabinet using a double-sided glue tape/pad. Finally, the LDR should not be mounted to receive direct sunlight. It must be mounted at the top of the enclosure, pointing to the sky say southwards. This circuit is very simple. So interested and experienced hobbyists can alter/modify the whole circuit as per their own ideas without any difficulty (Just try a 6V relay with T1 to drive more number of LED strings).
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Thermopile Sensors LMP91050

Thermopile Sensors seeing that typically used trendy NDIR applications
The LMP91050 is a programmable integrated Sensor Analog Front side (AFE) optimized on behalf of thermopile sensors, as typically used in NDIR applications. It provides a complete sign path solution amid a sensor and microcontroller to generates an output voltage proportional to the thermopile voltage. The LMP91050s programmability enables it to support multiple thermopile sensors with a single design because different to the multiple discrete solutions.
Thermopile


  • Programmable gain amplifier
  • “Dark indication” offset cancellation
  • ropes outdoor filtering
  • collective mode generator and 8 morsel DAC
  • Ideal pro NDIR Sensing, Demand control ventilation, Automotive CO2 hut control, Alcohol detection
datasheet download : LMP91050

source 

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Wednesday, October 29, 2014

Low Voltage Cut Out Circuit Diagram

This circuit will detect when the voltage of a 12v battery reaches a low level. This is to prevent deep-discharge or maybe to prevent a vehicle battery becoming discharged  to a point where it will not start a vehicle. This circuit is different to anything previously presented. It has HYSTERESIS. Hysteresis is a feature where the upper and lower detection-points are separated by a gap. 

Circuit diagram :

Low Voltage Cut-Out Circuit Diagram

Normally,  the circuit will deactivate the relay when the voltage is 10v and when the load is removed. The battery voltage will rise slightly by as little as 50mV and turn the circuit ON again. This is called "Hunting." The off/on timing has been reduced by adding the 100u. But to prevent this totally from occurring, a 10R to 47R is placed in the emitter lead. The circuit will turn off at 10v but will not turn back on until 10.6v when a 33R is in the emitter. The value of this resistor and the turn-on and turn-off voltages will also depend on the resistance of the relay. 


Author : Colin Michel - Copyright : 200 Transistor Circuits
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600 Watt Quasi Amplifier With Mosfet IRFP460

ACTK 400/600 Watt
Two versions of a robust module capable of delivering high powwer for extended periods.  The Actrk400 uses 6 n-channel Mosfets in the output stage to deliver around 400 watts into 4 ohms while the Actrk600 uses 12 n-channel Mosfets in the output stage to deliver power in excess of 600 watts into 4 ohms.  One constructor has achieved almost 900 watts with the Actrk600 layout using 12 IRFP460 Mosfets.

Actrk 600W schematic

ACTK 400W Layout

ACTK 600W Layout

 ACTK Power Supply
   Schmatic
  Layout power supply

Final Set up And Adjustment
No attempt should be made to set up or test a power amplifier module that is not correctly mounted on
a heatsink. Make sure the main power supply is fused and the work area is clear. First check all your
work and make sure the output devices are insulated from heatsink. The set up is done without an
input or a load connected to the power amplifier.
1. Check the power supply is operating correctly and verify the rail voltages. Switch the power
supply off and check with a multimeter that the rail capacitors have discharged.
2. Using a multimeter measure the resistance of VR2 and set it for maximum resistance.
3. Correctly connect the ground lead, the two positive leads plus the negative lead to the power
amp module.
4. Remove the PCB fuses and replace with 100 ohm 5 watt resistors. Connect a multimeter that
is set to the 20 volt scale across the positive rail 100 ohm resistor.
5. Check that the power supply connections are correct one last time and switch on. If the
multimeter reading goes off-scale, turn off immediately and find the problem. Check also the
100 ohm 5 watt resistors; they may have gone open cct.
6. If everything seems ok adjust VR2 to set the output stage bias current, by measuring the
voltage across the positive rail resistor. Adjust for a reading of 4 volts per output FET pair. I.e.
For a 6 FET board set for a voltage of 12 volts. This equates to a bias current of 40mA per FET
pair or 120 mA total. For the 12 FET board set for a voltage of 24 volts.
7. If everything seems ok, check the output offset voltage and adjust VR1 to achieve an offset of
less than 10 mV. You will need to wait briefly between adjustments for the offset to settle.
8. All being well switch off, back off the bias control trimmer (VR2) and replace the 100 ohm
resistors with 10 ohm 1 watt resistors. Switch on again and re-adjust VR2 to get 0.4 volts per
FET pair.
9. Switch off, remove the resistors and put the fuses back in. Switch on, re-check the offset
voltage and adjust with VR1 if necessary.
The amp module is ready, connect the input and output and enjoy.
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Tuesday, October 28, 2014

250mW 16 dB VHF amplifier Circuit diagram

A high efficiency simple 2-transistor VHF amplifier electronic circuit project can be designed using this electronic circuit diagram . This VHF amplifier electronic circuit has a very high efficiency of about 16dB gain, and requires no tuning or alignment procedures. Wideband techniques have been used in the design and the circuit is equipped with a "lowpass" filter to ensure good output spectral purity. This VHF power amplifier circuit is specifically designed to amplify the output of 7mW to 10mW WBFM transmitters to a final level of 250mW to 300mW, after the filter.
The output of this stage is around 70mW of RF power.
The transistor is biased by means of R5, R6 and L6, and the residual DC current is set by R4. The input signal is coupled by C9 to the Base of the transistor.
The input signal from Q1 is coupled to the Base of Q2 via C7.The 78L08 voltage regulator is used to regulate the supply voltage to Q1 and the bias votages to both Q1 and Q2 so that the output RF power is relatively constant, even with large variations of supply voltage.
The output of the amplifier is filtered with a low-pass filter to reduce the output spurious and harmonic content.
The output filter consists of C3, C4, L1 and L2.
This RF power amplifier must be powered from a simple 12 volts DC power supply circuit.
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Mini Roulette Circuit

A mini roulette circuit, whilst the switch S1 the output by pin 1 of the IC1a the voltage is “shrill”,The oscillator circuit output IC2b, IC2c go to work.timer pulse generator fed to IC3, a voltage “high” output to the output pins 3, 11, and pin 12 of the IC3, the LED1-LED10 light trail sequence. Section LED11 extravaganza high - low tip. The output of pin 3, 2, 4, 7, 10, of IC3 represented by high points,Output pins 1, 5, 6, 9, 11 in its place of the IC3 with the low points.The bonanza instead of the LED12.The IC1b, IC2a and IC2d in the role of controls.

Mini
Mini Roulette Circuit

Resistor R2 and capacitor C1 determine the era of the output “shrill” output from pin 1 of the IC1a. The capacitor C1 through R2. at what time you press the switch and the voltage dump across C1 pray regularly raise until the most level. It will reset the flip failure IC1a befall the output by pin 1 is “low”. And the oscillator output circuit to break off working, but in attendance are certain LED light are pending, it can exist with the aim of we put a stop to up being the LED. So fix not apprehension, it choice switch a little time.since, particular a instance full stop with the aim of the R2 and C1. The campaign are compulsory to keep a 6-volt power supply. If tainted is 9 volts, have to try in favor of security reasons.

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Monday, October 27, 2014

Input Stage Amplifier OPA134PA

OPA134PA Input Stage Amplifier Circuit Design schematics, box file middle name : OPA134PA Input Stage Amplifier Circuit. You are able to click on the picture to meet first size image. I constantly anticipation to facilitate this OPA134PA Input Stage Amplifier Circuit design schematics design pictures are able to help you at the same time as reference guide to build your DIY project!

Input Stage Amplifier
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Photo Transistor Detector

All of the circuits on the PCB are configured so with the intention of as the photosensors are dark, the output of the 556 timers want stay peak. The issue delay period of each one 556 timer can be tainted by selecting as it should be combination ideals representing the R7/C2, R8/C3, R9/C4 and R10/C5 pairs.The LM339 input detection voltage levels for the circuit while publicized is settle on on 1/2 of the supply voltage. If a subordinate before elevated detection level voltage is wanted, the standards of resistors R5 and R6 can be there misused to suit.hint as soon as power is functional to the circuit, the outputs of the 556 timers pray be piercing in place of 1 discharge delay period phase. (Until the timing capacitors hold charged to 2/3rds of the supply voltage.) in attendance are RESET inputs for apiece LM556. 

Photo Transistor Detector
These inputs complete not have terminal stop contacts but do have pads with holes to solder wires to if considered necessary. The RESET inputs might take place used to force the outputs of the 556 timers LOW until the timing capacitors have fully charged behind power is practical to the circuit but an outer timer would be required to accomplish this.This circuit does not require a regulated power supply and can carry on on supply voltages of up to 15 volts.

on behalf of in turn on other light detector circuits, comprehend Light Activated Detector Circuits by the side of this put.For added broad in a row on Voltage Comparators see the Voltage Comparator in sequence piece of paper by the side of this place.on behalf of further universal in sequence on LM556 timers see the 555 Timer Information bleep next to this place.threatening - If the polarity of the power supply for this circuit is reversed before the circuit is connected to an AC or else DCC source this circuit pray exist damaged. The most supply voltage meant for this circuit is 15 Volts.
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Sunday, October 26, 2014

Running Disco Light with IC 4017

The following article explains how to design a minimal Running Disco Light Circuit Diagram using IC 4017. The IC 4017 is a 16 pin dual featuring in line package IC consists of a 10 stage decade counter/barrier. further in a row in this area the IC 4017 configuration visit at this point.


Unpretentious Running Disco Light mechanism by 230V and has ceiling 800 W for every channel load. The circuit can direct in Disco mode furthermore, by concerning narrator terminal to audio transformer known, & switching S1 to audio mode. prevail on other in a row on how to design the plain Running Disco Light Circuit 
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Saturday, October 25, 2014

Mains Frequency Monitor Diagram Circuit

Here is a simple frequency counter designed to monitor the 240VAC mains supply. It as a frequency range of 0-999Hz, so it could also be used with 400Hz equipment. Standard TTL/CMOS logic is employed for the counters and display drivers, while an ELM446 (IC1) generates accurate 1Hz pulses for gating. This device utilizes a 3.579545MHz crystal for its timebase, as commonly found in TV and video circuits and even on old PC motherboards.

Circuit diagram:
Mains Frequency Monitor Circuit Diagram
Copyright: Silicon Chip Electronics Magazine
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Friday, October 24, 2014

230Volt LED Circuit

This is a circuit that is used to menhidupkan LED with voltage 230Volt, 230Volt it so that the voltage must be lowered in accordance with the needs of the LED itself. To lower it even necessary circuit as below.

230Volt

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Thursday, October 23, 2014

70 Watt MOSFET Audio Amplifier

This is use the MOSFET power amplifier circuit, amplifier circuit has a very good sound quality. With the noise is quite small, thus making the amplifier circuit is suitable for you to try. Heres the circuit.
Click to view larger.

 Power amplifier with a 70Watt power is able to issue a clear voice, and very and good loud.
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150 watts power amplifier circuit

Amplifier circuit is 150 watts power amplifier circuit is quite simple.
This circuit requires only 5 pieces of transistors as the main component of reinforcement. There is no equalizer option on this amplifier circuit because it can be said of this series is very simple, so do not you compare it with that sold in the market which are usually equipped with various sound system and equalizer settings. 

But to add to your collection circuit, this circuit is fairly easy and inexpensive to make and maybe one day you may need as a weak signal booster from your electronic circuit. Or you can also make this amplifier as an amplifier of high frequency signal from the output circuit animal repellent and I guarantee the results are very satisfactory.

150

Power supply required is two-polarity power supply is + - 45 volts. Maximum power that can be obtained by this amplifier circuit is around 150 watts. As the volume control you can add potensio or variable resistor 10 Kohm in series at the input. Use dispasi loudspeaker with 150 watts power. Use a heatsink on the transistor-transistor driver loudspeaker or amplifier late as Q1 and Q2.
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Wednesday, October 22, 2014

5 Volt Switching Regulator Power Supply

The switching regulator power supply used LM2575-5.0 on this schematic. You can make the stable voltage by using the 3 terminal regulator like LM317. However, because the output electric current and the inputted electric current are the same approximately, the difference between the input electric power (The input voltage x The input electric current) and the output power (The output voltage x The output current) is consumed as the heat with the regulator. Because it is, the efficiency isn't good.
5

Data sheet for LM2575 SIMPLE SWITCHER 1A Step-Down Voltage Regulator
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Saturday, October 18, 2014

30V 1A ic LM317 Variable Regulator

If you want used easy variable regulator power supply voltage 0-30V at current 1.5A max. I am like this circuit, because it is small but very good.
I uesd IC – LM317T it is quality products ic variable regulator,so i like make in other power circuit.
I made use of a 24Vac 1A transformer,The output of the transformer is rectified by diode 1N4002 or equiv ,and smoothed filter using 2200uF capacitors.
The float-voltage measured here for the 24V transformer was 34V-35V,it is unregulated DC voltage.
The VR1 is control output dc voltage 0V(1.25V) to 30V(32V) at 1.5A max all range.
It is advised that you use this ic with a suitable heatsink.

Main Part
– IC1 = IC LM317T or KIA317
D1-D4 = Diode 1N4002 or 1N4004 or 1N4007 x 4
C1 = Capacitors electroly 2,200uF 35V
VR1 = Variable Resistor 5K(B)
Other detail part,Please see in image.
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Friday, October 17, 2014

2 Watt FM Transmitter

CIRCUIT DESCRIPTION
The circuit is basically a radio frequency (RF) oscillator that operates around 100 MHz. Audio picked up and amplified by the electret microphone is fed into the audio amplifier stage built around the first transistor. Output from the collector is fed into the base of the second transistor where it modulates the resonant frequency of the tank circuit (L1 coil and the trimcap) by varying the junction capacitance of the transistor. Junction capacitance is a function of the potential difference applied to the base of the transistor T2. The tank circuit is connected in a Hartley oscillator circuit.

Components List

R1=220K
R2=4.7K
R3,R4=10K
R5=100ohm
C1,C2=4.7uF Electrolytic
C3,C4=1nF
C5=2-15pF
C6=3.3pF
Q1=BC547C
Q2=BD135
P1=25K
MIC=Electret Condenser Type
P1 act as condenser microphone volume level. For FM, coil will be small. Use thin gauge enamel magnet wire. the diameter of coil will be a couple mm: use ink tube from pen to form, and try 8-12 turns. Small inductance coils 
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6 to 15V DC to DC Converter

A very efficient 6V to 15V DC to DC converter using LM2585 is shown here. LM2585 is a monolithic integrated voltage converter IC that can be used in various applications like flyback converters, boost converters, forward converters, multiple output converters etc. The circuit requires minimum number of external components and the IC can source up to 3A output current.

6 to 15V DC to DC Converter  Circuit diagram :


6 to 15V DC to DC Converter Circuit Diagram

Here the IC is wired as a boost converter where resistors R1 and R2 are used to set the output voltage .The junction of R1 and R2 is connected to the feedback pin of IC1. Capacitor C4 is the input filter while capacitor C1 the filter for output. Network comprising of resistor R1 and capacitor C2 is meant for frequency compensation. Inductor L1 stores the energy for acquiring boost conversion.


Notes:    
  • Assemble the circuit on a good quality PCB.
  • LM2585 requires a heatsink.
  • Output voltage is according to the equation Vout =( (R1/R2)+1) x 1.23.
  • Capacitors other than C4 and C1 are ceramic capacitors.
  • Maximum output current LM2585 can source is 3A.
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Thursday, October 16, 2014

Build a Digital Electronic Lock Circuit Diagram

This Digital Electronic Lock Circuit Diagram shown below uses 4 common logic ICs to allow controlling a relay by entering a 4 digit number on a keypad. The first 4 outputs from the CD4017 decade counter (pins 3,2,4,7) are gated together with 4 digits from a keypad so that as the keys are depressed in the correct order, the counter will advance. As each correct key is pressed, a low level appears at the output of the dual NAND gate producing a high level at the output of the 8 input NAND at pin 13.

Read : Cheap Bicycle Alarm Schematics Circuit

Digital Electronic Lock Circuit Diagram

Digital
 

The momentary high level from pin 13 activates a one shot circuit which applies an approximate 80 millisecond positive going pulse to the clock line (pin 14) of the decade counter which advances it one count on the rising edge.

Read : Emergency Light and Alarm Circuit Diagram

A second monostable, one shot circuit is used to generate an approximate 40 millisecond positive going pulse which is applied to the common point of the keypad so that the appropriate NAND gate will see two logic high levels when the correct key is pressed (one from the counter and the other from the key). The inverted clock pulse (negative going) at pin 12 of the 74C14 and the positive going keypad pulse at pin 6 are gated together using two diodes as an AND gate (shown in lower right corner).

Read : Burglar Alarm With Timed Shutoff Circuit Diagram

The output at the junction of the diodes will be positive in the event a wrong key is pressed and will reset the counter. When a correct key is pressed, outputs will be present from both monostable circuits (clock and keypad) causing the reset line to remain low and allowing the counter to advance. However, since the keypad pulse begins slightly before the clock, a 0.1uF capacitor is connected to the reset line to delay the reset until the inverted clock arrives.

Read : 5 Zone alarm Circuit Diagram

The values are not critical and various other timing schemes could be used but the clock signal should be slightly longer than the keypad pulse so that the clock signal can mask out the keypad and avoid resetting the counter in the event the clock pulse ends before the keypad pulse. The fifth output of the counter is on pin 10, so that after four correct key entries have been made, pin 10 will move to a high level and can be used to activate a relay, illuminate an LED, ect. At this point, the lock can be reset simply by pressing any key. The circuit can be extended with additional gates (one more CD4011) to accept up to a 8 digit code.

Read :  Alarm Control Keypad Circuit Diagram

The 4017 counting order is 3 2 4 7 10 1 5 6 9 11 so that the first 8 outputs are connected to the NAND gates and pin 9 would be used to drive the relay or light. The 4 additional NAND gate outputs would connect to the 4 remaining inputs of the CD4068 (pins 9,10,11,12). The circuit will operate from 3 to 12 volts on 4000 series CMOS but only 6 volts or less if 74HC parts are used. The circuit draws very little current (about 165 microamps) so it could be powered for several months on 4 AA batteries assuming only intermittent use of the relay.
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Simple Daul Regulator Handles Two Input Voltages

The circuit in Fig 1 supplies both 3.3 and 5V to transitional circuits that employ both the new 3.3V and older 5V devices. Additionally, because the regulator accepts either 3.3 or 5V inputs, you could plug it into either a new 3.3V system or an old 5V system.The circuit consists of two sections: a dc/dc converter and a double-pole, double-throw (dpdt) switch. The dpdt switch comprises a pair of dual n-channel MOSFETs (Q2 and Q3) and their associated high-side drivers.

Upon power-up, the comparator in IC2 determines the state of the circuit. The comparator’s output, IC2 pin 6, goes to the input of the MOSFET driver, IC1. The driver internally generates a gatedrive voltage 8.8V above the device’s supply voltage. This high voltage drives the appropriate MOSFETs in Q2 and Q3.

IC2 is also the heart of a flying-capacitor, buck/boost dc/dc converter. Unlike other switching-regulator schemes, this topology needs no transformers. Transistor Q1 controls this section’s output voltage, VS. When VIN is at 5V, Q1 is off, forcing the section to operate as a step-down converter. In this mode, the section produces 3.3V, which goes to the output through Q3B. Also in this mode, 5V power goes directly through Q2A, and Q2B and Q3A are both off.
 
 
When VIN is 3.3V, IC1 turns on Q1, shorting out the 140-kΩ resistor and forcing the dc/dc-converter section into step-up mode. In this mode the converter section generates 5V at VS, powering the 5V output via Q2B. Also in this mode, 3.3V goes directly from the circuit’s input to the output via Q3A. Q2A and Q3B are both off.No-load quiescent current consumption is approximately 500 μA.

Lower-frequency converters would reduce power consumption at the expense of a larger inductor. The efficiency of the dc/dc-converter section is 73% in either mode. But because this power accounts for only half of the circuit’s output power, the circuit’s overall efficiency is approximately 80% with VIN=3.3V and 86% with VIN=5V. 
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Wednesday, October 15, 2014

2 Transistor Electronic Siren Circuit Diagram

This is the electronic siren schematic diagram which used 2 transistor BC547 and BC557. The siren is powered by 9V battery or power supply adapter and use 8 ohm speaker to produce the sound. The siren is controlled by the touch plate switch. If you touch the plate, then this electronic siren will be activated. 

2 Transistor Electronic Siren Circuit Diagram


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How To Build Hammonator Organ to Guitar Amp Conversion Circuit Diagram


In the world of electronics, vacuum tubes are almost obsolete. Nearly the last holdout, the cathode ray tube (CRT), is rapidly being replaced by the LCD and other new technologies. Despite this trend, the vacuum tube has seen a big revival in the field of guitar amplifiers, and to a lesser extent, hi-fi amplifiers. Vacuum tubes and related parts have become more readily available in recent years as numerous companies have tapped into this market.

The reason for the popularity of tubes in guitar amps involves the nice tones that are produced when tubes are driven to the point of distortion. For some background on this, follow some of the links on The Strat Monger. There are numerous solid state "modeling amps" that try to simulate vacuum tube amps with digital signal processing (DSP) techniques, but in the end, that method is never more than a simulation. It just aint the same as the real thing.

One can spend a large amount of money and time building a tube amp from scratch. Hammond organ ampifiers chassis are available on the surplus market for a reasonable price, they make a good starting point for a guitar amp. The difficult job of cutting chassis holes for the tubes and transformers is already done, one just needs to drill a few holes for the potentiometers and connectors. This project started with the amplifier from a Hammond M2 organ, chassis model AO14-1B.

  Hammonator Organ to Guitar Amp Conversion Circuit Diagram


Hammonator




The output stage of this amplifier resembles a fusion between a Fender Princeton Reverb, Fender Vibroverb and ham radio transmitter. With 6V6 output tubes running at a 420V plate voltage, it puts out approximately 18 watts of audio power. The 17" reverb tank provides a deep echoey sound. The "simpler is better" philosophy was used in the design, multiple inputs with their own preamp stages were intentionally avoided to reduce hiss. The amp is plenty loud, and the sound quality is excellent. The Hammonator amp has worked well driving both 12" and 15" guitar speakers.

The Hammonator Model 1 amp is a simplified version of the Hammonator 2RVT circuit. Builders can start with the Model 1 circuit and easily add the Model 2RVT Vibrato/Tremolo circuitry at a later date.There are a few unique features in this amp, and some slight deviations from the aforementioned simplicity goal. An optional fluorescent EM87/6HU6 "magic eye" tube (EM87 in action) is used for an output level meter, it is fun to stare at while playing. The EM87 uses a peak reading circuit that was inspired by this design then modified somewhat. There is a reverb send control (Dwell) that can be used to expand the variety of reverb sounds. Most Fender amps send only a full-strength signal to the reverb spring. By turning the reverb send signal down a bit, a less "clangy" and more "spacey" reverb sound results.

The Hammonator also features a negative feedback control. With the feedback control turned all the way to the left (max negative feedback), the amp compresses the signal and the waveform peaks are reduced. With the feedback control turned all the way to the right, the sound is louder and less compressed and approaches that of the popular Fender Tweed Deluxe (5E3) amps. The feedback control could also be called "Clarity", "Gain" or "Presence".

This amp uses four octal base 6SN7 dual triode tubes for most of the low level signal amplification instead of the more common 12AX7 or 12AU7 tubes. This was done because the chassis was already set up for the octal sockets. Boutique amp enthusiasts will probably like this feature since the 6SN7 tubes are older and may have more of a vintage amp sound. Fortunately, the 6SN7 is still easy to acquire. This amp has been "tuned" for good sound, the bias settings of all of the tube stages were tweaked while a guitar was plugged in. This process was used to optimize the musical qualities of the amp. Not all vintage 6SN7 tubes are the same, quieter Sylvania tubes were used for VT1 and VT3 to reduce the hiss, nosier RCA and GE tubes were used elsewhere. You can test for noisy 6SN7 tubes by putting them in the VT1 socket, listening to the hiss level and tapping on the tube to listen for microphonics.

It is possible to change VT1, the first preamplifier and tone recovery tube, from a lower gain 6SN7 dual triode to a higher gain 6SL7 dual triode without any wiring changes. This allows the amplifier to work better with low output guitar pickups. This trick is often done with other amps by swapping 12AU7, 12AT7, 12AY7 and 12AX7 tubes, they all share the same pinout but have different gains.

The newer and more common AO-29 (M3 organ) chassis would also make a good chassis for a guitar amp conversion. The three 9 pin tube sockets could be used for 12AX7 or 12AU7 dual triode tubes and the five 7 pin tube sockets could be filled with common 6AV6 tubes (similar to a single 12AX7 triode) or 6C4 tubes (similar to a single 12AU7 triode). A similar circuit layout could be used on the AO-29 chassis but the cathode bias resistor values on the 7 and 9 pin preamp triodes would need to be changed from the values used on the 6SN7 tubes. The AO-29 power transformer and output transformer are very similar to those used in the AO-14.

Connections:
Power Input - grounded 120VAC
Guitar Input - High Impedance
Reverb Send
Reverb Return
Speaker Output - 8 ohms

Controls:
On/Off (on the back)
Input Volume
Bass
Treble
Reverb Send (Dwell)
Reverb Return
Feedback (Gain)

Theory:
The AC power input circuitry was modified from the original Hammond circuit. The power transformer is old enough that it was designed to run on 110V-115V mains instead of the 120V mains found today. Running the stock amp on 120V produces higher filament and B+ voltages, the higher filament voltages can shorten the life of the tubes. This problem can be easily fixed by putting the 5V rectifier filament winding in series with the AC primary winding. The 5V phasing must be correct, the easy way to test this is to try both orientations and monitor the 6.3V filament winding, use the lower wiring that produces the lower voltage. When the tubes are plugged, the filament voltage should be very close to 6.3V.

A grounded plug was used, this is critical for safety. A 2 amp fuse and switch are used to provide a standard fused disconnect. The varistor on the transformer primary protects against line voltage transients, those can get multiplied on the high voltage output winding and cause damage.

The transformer high voltage winding is sent to a center tapped full wave rectifier consisting of two 1N4007 diodes. The high voltage DC is dropped through a typical chain of resistors and capacitors to produce the voltages used in the amp. The first resistor (150 ohms/2 Watt) is used to set the initial B1+ voltage that drives the power output tubes.

There is a lot of misinformation on the net about tube rectifiers vs solid state rectifiers and the effect on amp sound. This probably derives from the more efficient nature of solid state diodes and the resulting higher voltage when a direct substitution is done. Putting a resistor after the diodes drops the B+ voltage to a level that is closer to that achieved with a 5U4 rectifier. The diodes have the advantage of better efficiency due to the lack of a high power filament, the power transformer will also run cooler using diodes. The 1nF/1KV capacitors across the diodes protect against high voltage transients and eliminate RF rectification issues.

The 5H inductor choke is used to reduce hum in the preamp stages, the value is not especially critical. The 220nF capacitors in the power supply are fairly unique to this design, they improve the high frequency response of the amp. This is a trick that was borrowed from solid state circuitry. If you dont have any 220nF caps, 100nF caps should do the job.

The Vbias- negative voltage is derived from a half wave rectifier and a resistive ladder. The 25K bias control can be adjusted to set the idle bias level on the power tubes. Bias levels for both 6V6 and 6L6 tubes can be generated.

The guitar input stage (VT1b) is a standard class A triode amplifier. The 1K cathode resistor was chosen to bias this most important amplifier stage into the "sweet spot". The tone controls use the Baxandall tone stack configuration. This circuit has a much more distinct boost and cut operation when compared to many of the traditional Fender circuits. A guitar player friend had the amusing suggestion that the "Bass" and "Treble" labels should be changed to "Balls" and "Grit". The post-tone amplifier stage VT1a is another class A triode amplifier. Again, the 1K bias resistor was chosen for the best sound.

The reverb send amp VT2 gets its input from the tone control recovery amplifier VT1a. The 500K linear pot is used to adjust the reverb send level from half way to full. An audo taper pot was tried here, the linear pot had a better response. Both halves of VT2 are run in parallel, the 560 ohm bias resistor was chosen for the best tube drive level. VT2 runs slightly warm, with a bit of blue glow showing. A standard Fender "Twin Reverb" reverb transformer can be used to drive the reverb, I used a slightly heavier Buddy MC500 transformer.

The reverb return signal goes to two class A triode stages formed by VT3b and VT3a. The reverb return level is set with the 100K audio pot and mixed into the phase splitter stage (VT4) through a 5nF capacitor. The clean (non-reverb) signal is amplified by VT7, a 6AV6 triode wired as a floating cathode-biased stage. The 6AV6 isolates the reverb send and receive signals to prevent feedback, it also forms the heart of the vibrato/tremolo circuit in the Hammonator model 2RVT design.

The balanced phase splitter circuit is formed by VT4a and VT4b. This stage combined with the power tube stage is fairly close to the Fender Vibroverb circuit. The two opposite-phase drive signals are sent to the control grids of the 6V6 power output tubes. An RF power amp trick is used here to reduce potential radio frequency oscillation issues, 10nF capacitors bypass the screen grids to ground. These caps should not be confused with the unpopular tone-deadening control grid caps that were added to Post-CBS Fender Twin Reverb amps.

A triple feedback loop is used between the output transformer and the input of the phase splitter. The low and high cut loops reduce the sub-sonic and ultra-sonic gain, eliminating any tendencies to oscillate and generate radio frequencies. While experimenting with the circuit, some nearly dead power tubes were used, the tubes tended to oscillate when biased to a useful setting. These additions reduced that problem and improved the sound, RF superimposed on audio does not sound good.

A fairly heavy modem isolation transformer from a 300 baud vintage of modem was wired in series to make the low-cut inductor. When the amp is driving a speaker, there can be large resonances in the low bass part of the spectrum. A 12" speaker in an open-backed cabinet had a natural resonance around 70 Hz. Audio at the speaker resonance frequency is amplified to about twice the level as other frequencies, resulting in an exaggerated bass response and distortion. The low-cut feedback circuit offsets this resonance effect.

An earlier version (obsolete) of this amp used a different anti-resonance feedback (ARF) loop that consisted of a 300 ohm resistor, a series-wired modem transformer and a 1.32uF stack of capacitors that was tuned to cancel the speaker resonance. When feeding a purely resistive load, the amplifier has a fairly flat frequency response. The low-cut/high-cut feedback loop eliminates the need to tune the amp for individual speakers.

The 6HU6 eye tube circuit gets its control signal from the output transformer. The signal is rectified, low-passed and sent to the tubes control grid. The 10M bias resistor opens the tubes display farther during quiet operation. The 5K trimmer should be adjusted so that the eye tube display closes completely when the amp is played to maximum power.
Biasing the Power Tubes

If you want more than 18 Watts of power, it is possible to replace the 6V6 tubes with 6L6 tubes, simply re-adjust the bias control. The bias is set by putting a DC volt meter between the Imon1 terminal and ground. The Imon2 terminal can be checked to see if the power tubes are well matched. Both Imon1 and Imon2 should have similar voltages. The 6V6 tubes work well with a bias of around 0.17V (17 mA) and 6L6 tubes work well at around 0.35V (35mA). Tube bias setting is a trade-off between loudness and tube life. Generally, the bias should be set so that the tubes dont become too warm when there is no signal going through them.

Construction:
Here is a photo of the wiring side of the Hammonator 2RVT amp, it is essentially the Hammonator 1 circuit with a few additions.The stock Hammond amp chassis that this project was built on was dirty, rusty and filled with mostly useless parts. A wire brush was used to scrape off the rust and dirt. Leave the original filament wiring from the power transformer to the 6V6 tubes intact. You will need to move one of the filament wires on some of the 6SN7 tube sockets (formerly other tube types). The power transformers high voltage leads can be left connected to the 5U4 socket, the 1N4007 rectifier diodes can be wired to the pins of the 5U4 socket. The output transformers primary wiring should be left as-is.

The ground wires that connect all of the tube sockets should be left intact. Just about everything else can be clipped off, leave all of the transformer wires as long as possible. There were two plug-boards in the center of the amp. All of the wires between the plug-boards and the tube sockets were clipped at the tube sockets and the boards were removed. The wires to the screw terminals were also clipped off. Some of the plug-board capacitors were scavanged for use elsewhere.

A new 3-wire power cord power switch were installed in the small metal wiring box that is located behind the power transformer. Two of the downward-facing holes in the wiring box were expanded to fit the power cords strain relief and the switch. A plastic "pigtail" type of fuse holder was also installed in the box. The power cables green ground wire was connected to the chassis with a solder lug.

The two tall electrolytic capacitors were removed from the chassis. The silver capacitors hole was filed out and drilled to fit the 6HU6 eye tube socket. A sheet metal filler was installed in the black capacitors hole (the photo above was taken before this was done). The volume pedal tower was disassembled and the empty space was used as a "doghouse" for most of the electrolytic capacitors. The caps were secured to the towers bakelite spacers with panduit ties. The tower allows the amp to sit upside down without resting on the tubes, this is very useful when working on the amp.
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Tuesday, October 14, 2014

Tone generator circuit

Tone generator circuit

Simple, low component count tone generator. It can be adapted to create a morse code circuit, by adding a switch to the output.

How it works:

This circuit is based around the 555 timer circuit, used as an astable (free running) oscillator. The frequency (pitch) of the tone is set by the resistors and capacitors in the left side of the circuit. The first one is a potentiometer (variable resistor), this is our pitch control, which is basically all the external components you need. The capacitor to the far left is to reduce as much noise or undesired operation of the potentiometer, getting a smooth pitch change when adjusting.


You can find the timers datasheet by following the link: 555 timer
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Monday, October 13, 2014

Engine Motronic BMW M50 1 3 1993 Ignition System Wiring

BMW On 1993 BMW M50 Engine series, the ignition timing is electronically controlled and not adjustable using the Motronic 1.3. The DME control module uses engine load, engine speed, coolant temperature, and intake air temperature as the basic inputs for timing control. A direct ignition system is used. Individual coils are mounted directly above each spark plug. Each coil can be selectively controlled by the DME control module on a cylinder-by-cylinder basis.

The following schematic shows the 1993 BMW M50 Engine Motronic 1.3 Ignition System Wiring Diagram which consists of: battery, ignition switch, ignition coil, distributor, spark plugs and motronic control unit.
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Sunday, October 5, 2014

Zinc Carbon Battery charger circuit and explanation

They are cheap. The electrolyte used to leak but today they are usually much better protected. If they should leak then they will corrode all the copper in your equipment. the corrosion will travel down wires and eat its way through Printed Circuit Boards (PCBs). At high temperatures (25 degrees or more) Zinc-Carbon batteries will give up to 25% more capacity but the shelf-life will deteriorate very rapidly. Around freezing point their shelf-life can be extended by as much as 300% so one tip is to store them in the refrigerator.

Unfortunately they must be thrown away when they are exhausted. You can extend their life by up to 60% by using "Dirty-DC" to recharge them but this will also reduce the shelf-life.

Ry should be about 1.5 x greater than Rx. The resistors are determined by the charging current you want. With the circuit shown and size AA cells in a pack of ten cells, the battery voltage will be 15 volts. Discharge the battery to no less than 25%. To replace 350mA/H back into the battery over 10 hours we need to charge at 35mA.

Rx = (24 - 15 - 0.7) / (3 x 0.035) = 79 ohms

Ry = (24 - 15) / (2 x 0.035) = 128

You can also cook exhausted battery cells in the oven. About 80 degrees centigrade for five to ten minutes, no more or they may explode. This technique was demonstrated on UK TV in the series "Steptoe & Son" (h�r i Sverige i "Albert och Herbert"). I do not reccomend that you should try to sell the cells again as new batteries! 

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2SC1061 2N3055 LM358 CD4047 100W Square wave Inverter


This is AC Inverter. Input 12VDC from car battery to output 220V AC 50Hz or 60Hz at Square wave signal.
The main part is IC CD4047 and IC LM358 and Transistor 2SC1061 and 2N3055.
The transformer is 12V-012V Primary : 220V Secondary.
and current 3A up for power output than 100W.
Note:
C1 = 0.1uf metalized-film capacitor, 5% tolerance.
R1 = 47K for 50Hz output, 39K for 60Hz output.
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Saturday, October 4, 2014

5V Switching Regulator using LM2575 5 0

5V
This circuit of +5 V switching power supply uses LM2575-5.0. You can make the stable voltage by using Terminal 3 and LM317 regulator. However, due to the current electrical output and electrical current is introduced it, about the difference between electrical power input (x Input voltage power input) and output (voltage output x output current) is consumed as heat with the regulator. Because it is, the efficiency is not good. In the event that the switching regulator that only inputs the electrical energy needed to produce the input for the switching operation. Because it is, there is little power to consume with the regulator and is efficient.

DC to DC step down voltage regulator. Wide input voltage 8Vdc to 40Vdc.
  • LM2575-3.3 (3.3Vdc output)
  • LM2575-5.0 (5Vdc output)
  • LM2575-12 (12Vdc output)
  • LM2575-15 (15Vdc output)
  • LM2575-ADJ (1.23Vdc to 37Vdc output)
The switching regulator which introduces in this page is the type and step is to get the output voltage that is less than the input voltage. As the regulator, use this time, the output is 5-V fixation.
The controller switching stage such attacks may be the voltage that is higher than the input voltage.

IC LM2575

The LM2575 series of regulators are monolithic integrated circuits that provide all the active functions of a step down (money) switching regulator capable of driving a 1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V and adjustable output version.

Requiring a minimum number of external components, these regulators are simple to use and include internal frequency compensation and a fixed frequency oscillator.

The LM2575 series offers a high-performance replacement for popular three-terminal linear regulators. Substantially reduced the size of the heatsink, and in many cases no heat sink is required.

A standard series of inductors optimized for use with the LM2575 are available from several manufacturers. This feature greatly simplifies the design of switching power supplies.

Other features include a guarantee of ± 4% output voltage at the input voltages within specific conditions and output load, and ± 10% in the oscillator frequency. External stop is included, with 50 mA (typical) standby current. The output switch includes cycle-by-cycle current limiting, thermal shutdown and full protection for the failure.
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Friday, October 3, 2014

6V Ultra Bright LED Flashes

6V6V Ultra-Bright LED Flashes Circuit

At best speed, the LEDs don’t arise to flash, instead they arise to move from one afire one to the next, about and around. They circle absolutely for 4 rotations in two seconds, and again about-face off for a one additional abeyance again echo the sequence. At a lower speed, the cardinal of rotations afore the abeyance is less. It will do three rotations, two or alike alone one circling at its slowest speed. A arrangement of rotations starts with LED #2 and end with LED #9.

Specifications

Battery: Four AA alkaline cells.
Battery life:
Minimum speed and brightness 2.3 years
Medium speed and brightness 1 year
Minimum speed, maximum brightness 4.1 months
Maximum speed and brightness 3.8 weeks

Brightness: controlled with Pulse width Modulation, from off to extremely bright (4000mcd).
Stepper speed: 2 LEDs/sec to 2 revolutions/sec.
Pulse Width Modulation frequency: 3.9KHz.
LED current: 24mA pulses.
LED voltage drop: 3.2V at 24mA. Blue, green and white Ultra-Bright LEDs are suitable.
Minimum battery voltage:
<3v, oscillators do not run.
3V, LEDs are very dim.
4V, LEDs reach almost full brightness.
Radio interference: none.

Circuit Description

* The CD74HC4017N high-speed Cmos IC is rated for a maximum supply voltage of 7V. It is rated for a maximum continuous output current of 25mA. In this project, the maximum supply voltage is 6.4V with brand new battery cells and the 24mA output current is so brief that the IC runs cool.
* The MC14584BCP* IC (Motorola) is an ordinary “4XXX series” 3V to 18V Cmos IC, with a very low operating current and low output current. Its extremely high input resistance allows this project to use high value resistors for its timers and oscillators, for low supply current. Its 6 inverters are Schmitt triggers for simple oscillators and very quick switching.
* IC2 is a 10 stage Johnson counter/decoder. On the rising edge of each clock pulse its outputs step one-at-a-time in sequence. It drives the anode of each conducting LED toward the positive supply.
* IC1 pins 1 and 2 is a Schmitt trigger oscillator with C3 and C4 paralleled for a very low frequency. R1 and R2 control its frequency and the diodes with R3 combine with the capacitors to produce the 15mS on time for the LEDs.
* IC1 pins 5 and 6 is the brightness Pulse Width Modulation oscillator. The pot R7 with the associated diodes and resistors allow it to change the duty-cycle of its output for PWM brightness control. It drives the transistor.
* IC1 pins 3 and 4 is an inverter. It takes the low time (LEDs off) from the clock oscillator, inverts it to a high and shuts-off the brightness oscillator through diode D6.
* IC1 pins 11 and 10 is a sample-and-hold stage. It takes a sample of the pulse driving LED #9 though D3 and R4 and charges C5 in steps. At maximum speed it takes 4 steps for C5 to charge to the Schmitt switching threshold voltage. R5 and D5 slowly discharge C5 for the pause time.
* IC1 pins 13 and 12 is an inverter that resets the counter/decoder and shuts-off the clock oscillator through D4, during the pause time.
* IC1 pins 9 and 8 is not used and is shut-off by grounding its input.
* T1 is the PWM switching transistor. R9 limits the maximum LED current to 24mA.

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Thursday, October 2, 2014

Simple Accurate Capacitance Meter Circuit Diagram

ln this capacitance meter, the value of a capacitor is determined by giving it the same charge as a reference capacitance and then comparing the voltages across them.

This relies on the formula C = O/V where C is the capacitance in Farads, O is the charge in Coulombs and V is the voltage in volts. lf therefore two capacitances have equal charges, their values can be calculated when the voltages across them are known. Two circuits ensure that reference capacitor Cr and the capacitor to be measured, CX, are charged equally. The circuit for Cr consists of C2, Di and T1 and that for CX of C3, D2 and T3. Each time the output of gate N2 rises, the charges of capacitors C2 and C3 are transferred to Cr and CX { by trer:cFstorsT1 and T3 respectively.

When the output of N2 drops, C2 and C3 recharge via diodes D1 and D2. Gate N2 is controlled by astable multivibrator N1 which operates at a frequency of about 2 kHz: Cr and CX are therefore charged at that frequency. The voltage across Cy is compared by IC2 with a reference voltage derived from the power supply via R3/R4. When the voltage across Cr exceeds the reference voltage, com- parator IC2 inverts which inhibits N2 and causes N3 to light LED D3. The charges on Cr and CX are now equal and the meter indicates by how much the voltage across CX differs from that across Cr. Buffer lC3 presents a very high load impedance to CX. Pressing reset button S1 causes both Cr and CX to discharge via T2 and T4 respectively, after which the charging process restarts and the circuit is ready for the next measurement. The meter is calibrated by using two identical 10 nF capacitors for Cr and CX. Press the reset button and, when the LED lights, adjust preset P1 to give a meter reading of exactly one tenth of full scale deflection (fsd).

That reading corresponds to 1 x Cr. lf, therefore, Cr = 100 nF and CX = 470 nF, the meter will read 0.47 of fsd. To ensure a sufficient number of charging cycles during a measure- ment, Cr and CX should not be smaller than 4.7nF. To measure smaller values, capacitors C2 and C3 will have to be reduced. For instance to enable a capacitor of 470 pF to be measured, C2 and C3 have to be T0. . . 20 pF. The circuit is reason- ably accurate for values of CX up to 100 pl:. Above that value the measurement will be affected by leakage currents. To measure capaci- tors of up to 100 pF, the values of C2 and C3 should be increased to 1 AF. Current consumption is minimal so that a 9 V battery is an adequate power supply.



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Wednesday, October 1, 2014

Simple Photo transistor Light Sensor Driver Circuit Diagram

  1. The computer can be programmed to monitor the output of the light t detector, and automatically arranges for the relevant lights to come when it gets dark.
  2. The sensitivity can be made adjustable for particular requirements by replacing R1 with a series connected 10 KQ preset and a 2709 resistor.
  3. This circuit provides a computer with information about the presence of daylight.
  4. The circuit is simple enough to enable ready construction on a piece of veroboard. Its output is TTL compatible, and logic low when the phototransistor detects light.
  5. Possible applications include automatically measuring the duration of the daylight period in an autonomous weather station, or in control systems for outside lighting around the home. 
Simple Photo-transistor Light Sensor Driver Circuit Diagram is shown below:


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