The kombi dont have an accessory switch right. So when I am waiting for various family members to do something I am without sounds, unless I leave ignition on, which opens up all sorts of coil cooking point burning issues. While I could run it bypassing the ign, its not good cos I would soon leave it on. A lot of the time I have to turn the volume down for wahtever reason.

So this is what I want to do. Have it run through ign as normal, but ALSO, I want to have a pushbutton switch that turns it on as well. Cant be a toggle switch cos I would forget that too. Have to use 2 relays I think. One to hold power on when button is pressed, one to release the first when the ign switch is used.

Without hassling me about my CAD skills/wrong symbols etc, will this work? Is there a neater way.

i have this same problem and i was going to hook up a toggle switch on the dash for it. perhaps one that lights up so its harder to forget.

looks reasonable for a rough diagram but you would want to use a latching relay to hold it on. give me a little while and ill have a good diagram as some thing i work on has a similar setup

here is it with the right symbols and a few other things. this should work cause its a similar setup on the 30mm cannon. ive added a couple of reverse voltage diodes.

RL1 is a normally closed relay and RL2 is a normally open relay( you may want to put a latching relay in for this one with a normally closed switch in its power line to turn it off)
good luck mate that was a good challenge NEXT!

I know what a diode does, but what are these 2 particular ones doing?

they protect the relay from a reverse current which can damage some relays and i didnt mean to treat you like an idiot its just some thing ive developed from work after dealing with people who have no idea

its cool, I never thought that. I used to know all the basic symbols. I did a PLC subject way back when I was a whipper snapper. Did lots of subjects. Only if you dont use them after the exam, they just get lost somewhere. I'm a rigger as well but wouldnt trust myself tying anything more important than a shoelace.

yeah well it took me a couple of minutes to think about it but im still not sure about the direction of the diodes but thats the direction they are in my 30mm manual so it must be right. btw im an electronics technician but i havent done any circuit designing in 3 years

If the Diodes are installed incorrectly......
You'll soon know.... ..

I have never used diodes on relays...

Do You think its a necessity?? or only on Solid state gear??

I am doing some work on My Sons Baja tomorrow, maybe I should add one to each relay... I have heaps on hand....
I am a Ham Radio operator but haven't done any building etc for many years..... but still have lots of bits & pieces....
I have forgotten most stuff from a nervous breakdown...
and now have very little memory of it all....

Lee

[Edited on 16-8-2004 by 68AutoBug]

have never used diodes to protect relays from "reverse current" as you put it. when is it possible to get reverse current flow??

if you think you will forget to turn the circuitry off then use a switch that will light up when its on... or you could always install one of those huge lights on the dash to tell you its on... :thumb

forgot to ask.... why are you running a relay for the cd player????? you can always just run directly from the battery (or somewhere at the fusebox which is always powered), through your on/off switch and to the cd player... most switches will handle the small current for the cd player.

They arent there for protection, but an automated method of switching. Because I dont want a switch that stays on by itself. That would mean I have to remember to turn it off.

When I press a push button switch, R2 holds the power on while I sit there waiting for my daughter to finish ballet. When I turn the ignition on to leave, R1 cuts the power to R2 and the CD circuit works as normal.

I like your relay idea, but...

I have an auxiliary battery for the stereo, cabin lights, fan, fridge etc. so I can leave the stereo on with the ignition off, and who cares if it runs the auxiliary battery flat: the main battery will still start the motor

Just a thought - some switches have three terminals , if you feed the 12 volts into the middle terminal of the switch you take the output depending on which way you flick the switch out to one of the outside terminals.Now if you feed 12v from the ignition to one of the outside terminals and 12v permanent supply from the headlight etc. to the other outside terminal then depending on which way you flick the switch you should be able to supply the radio via the centre terminal from the ignition ( while car is running ) or permanent supply while car is turned off.
should work

Just a thought - some switches have three terminals , if you feed the 12 volts into the middle terminal of the switch you take the output depending on which way you flick the switch out to one of the outside terminals.Now if you feed 12v from the ignition to one of the outside terminals and 12v permanent supply from the headlight etc. to the other outside terminal then depending on which way you flick the switch you should be able to supply the radio via the centre terminal from the ignition ( while car is running ) or permanent supply while car is turned off.
should work

Seems like you're adding unnecessary expense with two relays - simply use a relay with NO contacts and wire them in series with the coil. Put the first PB switch (NO) in parallel with these contacts. Put the second switch (NC) in series with the whole shebang. Leave the diode in, as shown - it actually reduces back-emf which will interfere with other electronics (such as the radio) and a small capacitor, say 1nF across it would be a good idea.