Hi

I'm trying to replace the rocker switches in my car for some push buttons. I have asked the manufacturer of the switches I have chosen if they do them as a latching type, but they don't. So here is my Dilema :? .
Each circuit will have only one momentary push button and the circuits need to latch. :shock:

I have a rear fog light that needs to come on when the button is pressed and go of when the button is pressed a second time. I assume that the circuit will first drive a relay, that will in turn supply the fog light.

The second circuit wil operate as follows.

Push button press 1 - Fan speed 1 signal sent to relay.
Push button press 2 - Fan speed 1 and 2 sent to relays.
Push button press 3 - All fan signals removed.

Any diagrams or advice would be much appreciated.

:?: Some questions.

Does the resistance of the automotive relay play any part in the design of the circuits?

Am I right saying that the circuit will also need a debounce circuit?

Do you think that standard relay contacts would suffer from making and breaking with the vibrations from a car? Is that why we have automotive relays because they are designed to be able to cope with this?

Can you suggets a good book to start off with learning anout digital electronics that wil take you through from complete beginner to moderate. So that I could be able to design this circuit myself in the future?

Thanks for taking the time to read this post

Lee

 

Could I use a 4 bit shift register and set the data high. Use the signal from the push buton with a debounce circiut to send the clock signal. Use output 3 to reset the shift register. Use transistors to drive the relays. Am I going in the right direction?

Cheers
Lee

 

hey dude look up KJ Flip Flop on google i would post a pic but damed if i can work out how............ oh there ya go i worked it out

ok forget the pic this dude has done exatly what you want allready

http://www.cpemma.co.uk/flipflop.html

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Hi Lee,

That would be a perfect application for a little 8-pin PIC microcontroller (approx. $1.50 USD)... The switches are easily debounced in software... Use the MRF series N-channel MOSFETs if you need higher current or more heat dissapation... Connect the relays between each relay output pin and 12 volts...

If you're not familiar with PICs, this is probably not the best solution...

Have fun... Regards, Mike

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Thanks for the replys guys. I got the circuit working by using a 4 bit shift register with the data set permanantly high, the clock pulse via a simple debounce, and output three connected to the reset. I have tested the circuit and it seems to work perfectly. It also gives me the option of creating a three speed fan latch very easily.

Thanks again
Lee

 

hell yeah go with the pic idear i would, much easyer if you know how to use a pic, if not im sure we help ya with the programming

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There Are 10 Types Of People, Those That Understand binary And Those That Don\'t