LIGHT_SEQUENCER

Published:2009/6/17 1:52:00 Author:May | From:SeekIC

The light sequencer uses two ICs and 10 SCRs to create an ac sequencer. The first IC, a 555 timer, is used to provide clock pulses for IC2. The IC is configured as an astable multivibrator, and its output is on pin 3.Capacitors C1 and C4, along with resistor R2 and potentiometer PI, control the frequency of the pulses. IC2 is a 4017 Johnson counter, which shifts a high-signal level to each one of its 10 output pins in sequence. Each output pin is resistively coupled to the gate lead on an SCR. When the re-spective output pin on the 4017 is high and the positive half of the ac cycle is on the anode lead of the SCR, it turns on. The lamp that is connected to its anode lights.Power is brought into the PC board by the line cord, then the circuit is fuse-protected. Diode LD1 changes the ac to pulsating, which is smoothed by CZ and C3. R23 limits the current, and zener diode D2 limits the dc voltage to 6 Vdc. CI，040.1-μF Capacitor R2，R4，R6，C2 100-μF Capacitor R8，R10，R12，C3 47-μF, 350-V Electrolytic Capacitor R14，R16，R18D1 1N4007 Diode R20，R22 100-kΩ ResistorD2 6-V Zener (M747814)R3，R5，R7IC1 555 Timer IC R9，R11，R13IC24017 CMOS IC R15，R17，R19P1 500-kΩ Potentiometer R21 2.2-kΩ ResitstorQ1-Q10 106 SCR R23 15-kΩ 7-W ResistoR1 560-Ω Resistor



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