06 March 2015

Modified 2 stage blinker circuit for LEDes and brakelight

This circuit is like an advanced version of first blinker circuit, it uses 2 astable circuits, not 2 IC. We can use 556 here. 2 Astable multivariator of Low and High frequencies are cascaded and gives good programmed pulse like 1 long pulse and 2 to 5 sort pulse (Depends upon setting).

The below circuit shows Multi-function blinker circuit

Components:

IC: U1A,U1B : LM556 (Duel timer IC)
Resistors: R1: 1.2K, R2:1K*, R3 750 Ohm, R5:220 Ohm
Pot: R4:1K Ohm, (R2:2K*)
Diode: D1,D2,D3: 1N4007.
Transistor: Q1: MJE200 or any power NPN transistor.
Capacitors: C1:100uF, C2,C4:10nF, C3:22uF.

Description:

  • The First stage multivibrator is set to 5 hz, 50% duty cycle (on off 5 times in second ;) ).
  • The second stage is a variable one. it varies from 15hz to 160hz
  • When first stage in OFF state the second stage is ON -> High only
  • When first stage is ON, The trigger circuit will activate second stage and low frequency pulses

Output graph:


PCB Layout & Project files:





If any problems, Comment below




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