Car radio delay

[Bob46320]

I have just installed a car radio in my '79 1000 "special". It works fine, just as advertised. It will only work with the ignition on, key positions
position 0 All OFF, - remove key
position 1 for TOWING, (I don't think there is an electrical contact for this position)
position 2 Ignition ON - radio works fine
Position 3 START.

I would like to listen to the radio with the ignition OFf ie: working under the bonnet etc, but limit play time to say, 15 mins in case I wander off and return a few days later with a flat battery!

Is there a bit of kit that would do this. The radio is a cheaper one and does not have auto shutdown, but it does have 2 live feeds, one unswitched for radio memory and a second via the ign switch for playing.

Bob

[Catmint]

could you coble something to gether with something like this

https://www.12voltplanet.co.uk/timer-relays.html

[Bob46320]

What I am concerned about is that when the radio is on "timed", that it doesn't feed back into the ignition circuit and hence back end of the alternator and coil.

[Spider]

While this is for a Rear Window Demister, it'll also work with your music box;-

https://www.carbuilder.com/uk/heated-window-timer-relay

If you have a more serious boom box, you'll likely need another relay with this one that has higher rated contacts.

Noted this one from CBS is out of stick, but there's many brands of these, eg Narva, Red Arc etc.

[Bob46320]

Yes, it would give a delay, but I wouldn't want to have to re-set it every 10?? mins , also when playing the radio under timed conditions, the O/p from the relay would have to be connected back to the ign circuit so it would play under normal conditions.

I could see that a bit of "electronics" would be needed (something like an SCR) to stop the current flow back to the ign.

Just thinking about it, a simple timing circuit and a Double pole Normally Closed relay would work.
Bob

[snoopy64]

12volt planet do ones adjustable up to 6 hours

[minibitz]

Just a thought, wouldn't it be way easier to just get an el cheapo transistor radio to keep in the garage?

[Bob46320]

Minibitz - But where is the fun in that ?

[Spider]

Yes, it would give a delay, but I wouldn't want to have to re-set it every 10?? mins , also when playing the radio under timed conditions, the O/p from the relay would have to be connected back to the ign circuit so it would play under normal conditions.

I could see that a bit of "electronics" would be needed (something like an SCR) to stop the current flow back to the ign.

Just thinking about it, a simple timing circuit and a Double pole Normally Closed relay would work.
Bob

Just fit a SPDT Switch (or sometimes called a change over switch) to feed the Radio.

In the 'normal' position, it would feed the Radio in the normal way via the Ignition Switch and the timer would not come in to play. In the 'Garage' mode, it would be fed of the battery via the timer.

Not sure what model Mini you have but if you wanted to fit a SPDT Switch that matches the other switches in the dash, use a Wiper Switch.

[Bob46320]

Thanks Spider - simple neat idea. Tie a label to the garage key - DON'T FORGET TO TURN THE RADIO OFF.
Bob