Thinking of fitting a tarty start switch on my dash. My electronics skills are basic so go with me on this one!

I was going to use a relay as I'm not 100% sure the switch is up to the load. I wanted to stop the switch being able to work once the engine had started. My thoughts was to use a zenor diode to supply the relay + feed via the switch, with the diode "trigger" supply coming from the oil presure switch. The idea being that the relay would work as long as the oil presure light was on, and continue to work after the oil presure switch dropped the supply to the trigger, but once the start button circuit was broken the diode would no longer allow current to flow again until the oil presure switch supplied another feed to the diode trigger.

If you got all that well done!

My whole cunning plan is based on the idea that a zenor diode will only allow current to flow when its trigger connection gets a voltage applied to it, and once current flows it will be able to do so regardless of the condition applied to the trigger until the flow stops, then the who process needs to be repeated.

Any help comments and all that...

Why not make the oil pressure switch, switch a relay to cut the power to the start switch? Will deffo work!

Our's is a BEC and has a SB. It's not like you can't hear the engine running and mistakenly press it again. No sir!

But if that's what you wanna do.... good luck!

Good plan till you stall in traffic and have to wait for the oil pressure to disappear before you can restart. It can take 30+ seconds in my pinto engine.

Are you thinking of a transistor zetec a zener diode is essentially a voltage regulation device.


I would think a timer device on the ignition switch would be a better bet, maplins do a kit for a few quid which would latch on for a predetermined time (settable by your self)which would give you "x" seconds to hit the starter button.

I'll find the code for the kit and post it later.
Cheers,
Bob

Pete, not using that spare gearbox oil in the engine again are you!

The idea was that I could possibly still crank the engine if the oil presure light had gone out, but once I had let go of the button when the engine was running it would make no difference if my younger passangers pressed it again.

Of course, you have to recycle . If they have a belt on they won't be able to reach it anyway, unless they are part octopus .
10/40 actually though.

Take the feed from the alternator charging wire rather than the oil pressure switch, the reponse will be much quicker.

quote:

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Originally posted by silex
Take the feed from the alternator charging wire rather than the oil pressure switch, the reponse will be much quicker.

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Sounds better to me. A zener diodes going to do nowt tho.

Cheers,
Bob

I think that if you intend to use the oil light supply to operate a current controlled device you should be looking to use a silicone controlled rectifier, (also known as a thyristor), as Bob says a zener diode won't work, at least not by itself.

Mick

If you are not electronically minded, then using a relay is probably your easiest way to go.

Connect the alternator charge wire to the relay coil. Connect the other side of the coil to ground. Connect your push button switch to 12 volts on one side an the other side the unswitched pin on on the relay. This will leave you with two pins on the relay. One is normally closed, the other normally open. you need to connect the normally closed side into the rest of your normal start circuit.

When you then press the start button the engine will start, the alternator charge then energizes the relay, cutting the start button out of the circuit.

Sorry for no picture, but I'm at work and unable to attach one.

There are of course more sofisticated ways of doing this, but I thought you wanted it simple to follow.

Why do you need a relay? Surley there is one in the system anyway. All i di was take the relevant wires off the barrel and solder to the push button.....worked a treat.

It was a sierra based system.

A timer in the system sounds the simplest way.
Surely if your younger passengers touch the button a clip round the lug hole will make them leave it alone?..,.

Not meaning to affend with that comment..

If you are using the ignition switch from the donor car then why not just put the output from the key start position through the start button. This way the key needs to be turned and the button pressed at same time. When the key is released then the button is safe.

Terry

Anyone knows how the Renault laguna has the SB system working?

i mean what if you are driving and pushed the button?????

and what if you take out the card while driving???

TKS

The final turn on the key on one of familys cars stoped working, only the final turn to work starter motor.

A wire was run from the + terminal of the starter motor to a push switch on the dash board and then back to the solinoid on the starter motor.

This makes a change from using a screwdriver to link + terminal and solinoid.
Works a treat but would advise using a switch with a flip open cover to prevent accidently pressing switch.

[Edited on 26/2/05 by clbarclay]