Voltase hobby

The mixer schema below has 3 line inputs and 3 mic inputs. The mic inputs are suitable for low impedance 200-1000R dynamic microphones. An ECM or condenser mic can also be used, but must have bias applied via a series resistor. As with any mixer schema, a slight loss is always introduced. The final summing amplifier has a gain of 2 or 6dB to overcome this. The Input line level should be around 200mV RMS. The mic inputs are amplified about 100 times or by 40dB, the total gain with the mixer is 46dB. The mic input is designed for microphones with outputs of about 2mV RMS at 1 meter. Most microphones meet this standard.

This is an Infrared beam breaking alarm ideal to use in entry or passages.It is based on the working of the popular IR sensor Module TSOP 1738 which senses 38 kHz Infrared pulses from the IR LED of the transmitter. Range of the schema is about 5 meters if the transmitter and receiver are properly aligned TSOP 1738 IR sensor module responds to only 38kHz pulsed infrared rays. Circuit diagram :   IR Beam Breaker Schematics Circuit Diagram It will not sense continuous IR ray from the IR LED.So a transmitter schema(as one in TV remote handset) based on 555 IC is required. Any standard transmitter schema based on 555 IC can be used. But its output should be 38kHz exactly.TSOP 1738 gives 5 volt output and 5mA current in the off position. That is when IR rays are not available.Its output is current sinking so that when it receives 38kHz IR rays, output becomes zero.Pin 2 of the module should get a supply voltage between 4.5 to 6 volts.Higher voltage above 6 volts will destroy the device. The module is generally immune to ambient light, but may responds to sources of noice such as electronic ballasts. Out put from the IR module is given to the inverting input of IC1. LM311 is a precision voltage comparator . It looks like the common Op Amps like LM741, CA3130,CA 3140,TL071 etc.But its pin connections and output are different from other Op Amps. Pin 2 Non inverting Pin3 Inverting Pin 1 Ground Pin8 Vcc Pin7 Current sinking Output

The non inverting input of IC1 is connected to a potential divider comprising R1 and R2. When the IR sensor gets IR pulses from the transmitter, output of IC1 remains high. When the IR beam breaks, output from the sensor becomes high which triggers IC1. It then sinks current to activate buzzer and LED.