Astable Multivibrator

Thread Starter

Coat53y

Joined Aug 13, 2013
2
Hi guys,

I have an astable multivibrator with a 555 timer and at the minute it runs through a sequence, from the circuit board there is a 12v power cable and then 2 seperate banks of 3 sets of 2 leds.
the sequence is as follows:
flash right twice-flash left twice
flash left and right together 3 times
speed up-slow down
loop to beginning
all i want it to do is flash left twice then right twice then back to left twice then back to right twice in a loop.
i have uploaded a picture of the circuit board, hope you can help.
thanks
steve
 

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Thread Starter

Coat53y

Joined Aug 13, 2013
2
sorry bountyhunter,
the question is is there anything i can add or remove from the board to make it flash left twice and flash right twice instead of running in a sequence? I wouldnt know where to start in drawing a schematic hence the pictures
regards
steve
 

Shagas

Joined May 13, 2013
804
sorry bountyhunter,
the question is is there anything i can add or remove from the board to make it flash left twice and flash right twice instead of running in a sequence? I wouldnt know where to start in drawing a schematic hence the pictures
regards
steve
For someone to advise how to modify a circuit they should see the circuit first.
You already got one. It's on that breadboard. You should reverse engineer it first :look at the components and the traces and draw up a schematic from them .
The someone will look at it and give a suggestion .
 

wayneh

Joined Sep 9, 2010
16,114
Are you sure there's not more to the circuit somewhere? That's an awfully complex behavior for such a simple PCB.
 

absf

Joined Dec 29, 2010
1,942
I dont think IC1 is a 555. A 555 would not be able to flash led in such a complex pattern. I'd guess is it is a 12Fxxx PIC or ATtinyxx and IC2 is a 78L05.

Allen
 

tracecom

Joined Apr 16, 2010
3,944
I dont think IC1 is a 555. A 555 would not be able to flash led in such a complex pattern. I'd guess is it is a 12Fxxx PIC or ATtinyxx and IC2 is a 78L05.

Allen
Agreed.

@Coat53Y,

Look at the 8-pin IC, and post the letters and numbers you see on the top. Of course, if it is a microcontroller, there's no (easy) way to reprogram it because (a.) it's soldered in the PCB, and (b.) you probably don't have a programmer. :(
 
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