auto delay off indicators ?

I have an old car (1930) with a 6 volts positve earth electrical system. Although it has semaphore arm type turn indicators, I have installed a modern flasher type system . It works fine . The problem is , I often forget to cancel the idicators ,
I need a simple way to to auto cancel the signal after say 20 seconds.
I have tried using electronic devices  based on the 555 timer. These work fine until the engins is started, causing the circuit to become un balanced, so its real hit and miss as to reliabilty. mainly due to the fact that the working voltage of the 555 is 5 -- 18 volts.
Can anyone suggest a way around this problem.

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gasper1 (author) 6 years ago
I am trying different approach. to this problem, it's this;
I intend using a seperate 9v supply fron a P9 battery to power up the pcb (delay on)
combining a n/o -n/c contact
The flash unit and seperate 6v relays will still be powered by the the 6v positive earth of the car. This way, I hoping to overcome the fluctuating voltage problem to the 555 timer.
Will let you know how I get on.
Add LOTS of supply filtering and a metal case for the electronics.

Are you using a regulator to feed the 555 ?

gasper1 (author)  steveastrouk6 years ago
Hi Steve,so far I have tried , ; 1) transister and zener diode with extra smoothing
2) Aluminium case.
3) locating the unit in trunk of the car (radio Interferance)
4) LM 317 with 1000u cap. ect
The problem I think, is that the voltage regulator of the car is rather crude , bearing in mind it's age 1939 , this means that the voltage level is anywhere between 5-7 volts . This together with the fact that the dynamo output has no smoothing or rectification. so whatever is buzzing around the power lines is pretty nasty with loads of spikes which the elecroincs don't like.
Perhaps the solution is mechanical ! but don't give up !
In that case, try a switching regulator, or a DC-DC converter

Something like this

I'd add a zener across the input too if I were you.

Where are you in the world ? I can advise a suitable source if I know where to source it from !

gasper1 (author)  steveastrouk6 years ago
Hi Steve, I am located in Lancashire, England. My electronic store is Maplin , like your Radio Shack .I am assuming you are somewhere in the good old US of A .
Lucky you !
We have no such device as your AnyVolt, it sounds to good to be true, I WANT ONE. ! can you tell me where from .
I am not to sure how to configure a Zenor across the supply, any chance of a small schematic !
Again , Many thanks
ps thought you might like a pic of my "Dolly"
Nope, I'm in Heywood near Rochdale !

Which is your local Maplin ? Preston or one of the Manchester ones ?

I can give you some Farnell or RS codes as well as a circuit.

Nice car. Looks great.

gasper1 (author)  steveastrouk6 years ago
did you get my last Email ! sent Sunday @ 16.30