Steering wheel remote control switch modification

MikeT · Unread post by **MikeT** » 08 Oct 2007, 15:34

The steering wheel switches are the rocker type that (presumably) conduct current only when held. Is it possible to change this to a standard on/off feed? For instance, push the "volume up" rocker and it switches on a circuit, push a second time and it switches off? Is there a simple or common device/relay I could get from maplins for instance?

Unread post by **CitroJim** » 08 Oct 2007, 17:32

You would need either an RS flip-flop or a bistable latch for this Mike.

These are implemented in 74 series TTL or 4000 CMOS logic ICs or you could make up sets of latching relays to implement a bistable.

What is your idea Mike? I'm curious

MikeT · Unread post by **MikeT** » 08 Oct 2007, 18:08

Initially, just an activation switch for arming/disarming the nitrous circuit.

Later I may get a progressive controller which has (four I think) front panel mounted push buttons which I presume won't need such a modification. I'm currently in liason with the manufacturer to see if they are indeed push & hold type controls and if I can tap into these in which case the steering wheel rocker switches will be ideal without modification.

The freed space below the radio will make a neat hidey hole for the controller and with the steering controls connector being behind the radio, would allow minimal and neatly hidden wiring.

Unread post by **CitroJim** » 08 Oct 2007, 18:19

Ahh! I guessed as much Mike...

MikeT · Unread post by **MikeT** » 08 Oct 2007, 19:42

Care to tell me more about the flip-flops and bistable latches, or do I ask google?

I nearly got driven over by a massive humvee-type truck the other day, I need more oomph Jim!

dan_the_v8man · Unread post by **dan_the_v8man** » 09 Oct 2007, 01:39

what about something a bit more simple, using the switch to latch a relay on and then use the other contacts to drop the relay out, may need a second relay to convert the normally open contacts to normally closed for the off function

MikeT · Unread post by **MikeT** » 09 Oct 2007, 08:18

I was hoping to get the on/off action from just one pole/throw of one rocker switch.

Unread post by **CitroJim** » 09 Oct 2007, 12:38

Mike,

Wiki is your friend...

http://en.wikipedia.org/wiki/Multivibrator

No giggling at the title of the subject

Look down the page for Bistable Multivibrators...

You need two transistors.

As Dan says, the same can be done with a small relay but much more elegant with transistors or even TTL or CMOS Logic ICs. You can make a Bistable using NAND gates, either using a 7400 (TTL) or a 4011 (CMOS)..

MikeT · Unread post by **MikeT** » 09 Oct 2007, 16:22

Jim, I did read about RS flip flop and bistables last night and even went on to read about the IC's but I can't see any that flip from the one input only, they all appear to require two or am I missing something?

I may as well abandon that idea and just fit the kit activation switch in a xantia switch blank. I can then use the steering wheel switches to control the black box instead - I've been told it uses unlatched buttons that I can hack into at the pcb

But in doing so will have to pass up on the extended warranty it has.