Friday, October 3, 2014
6V Ultra Bright LED Flashes
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.
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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