An old electronic flasher for automotive

Post author: Carlo Han
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Posted on 2021-01-12 Edited on 2021-04-23 In HW Views:
588 1 mins.

Analyzing and simulating the working principle of an old electronic flasher. This flasher control unit is used to control the position, direction and emergnecy lights flashing on vehicle.

Last month I opened an electronic flasher for automotive, it’s an old version which designed by transister, not IC. I have been busy testing a new BMS all month, and until now I have no time to talk about this component. The schematic copy as below.

Schematic

Pin B is the positive 12V, pin E is ground, pin L is connected to a direction light lever. It was replaced by a 820ohm resistor. Let’s see what will happen in the simulation.

Voltage(LED) - T

The direction light flashes every 300 ms, and there is no clock no timer no mcu, only a little basic electronic components. Let’s analyse how it is realized.