12 Volt Timer

[zapj]

Has anyone noticed a 12v timer in their travels. I was thinking about one for either an appliance or for a lighting circuit. It may come in handy for turning off the lights if you fall asleep early.

[48Rob]

Hi,

There may be a 12 Volt timer available, but a 120 timer will work just as well, and likely be cheaper.

I used a 15 minute timer for my bathroom fan, cost twelve dollars.
There are also 30, and 60 minute timers available.

(The 120 Volt timer doesn't care if you run 12 Volts through it, just don't go the other way).

Rob

[Rob]

Rob--

Isnt' it kind of tough to get those two or three prongs of a 120V timer into the cigarette lighter for 12V?

[jo_tigger]

If you just want to turn off lights and appliances a standard windup timer will work. Of course the tick tick tick might keep you up all night. These timers are hardwired and generally install in a switch box in place of the on/off switch. They are also rated for AC loads so think about what you are attaching. I think they might make some that are quiet. 12 Volt Digital timers will cost considerably more and are mainly used to turn on and off devices.

[48Rob]

Richard,

You're right, I should have mentioned that they can be noisy...

If you have a tv. or a fan going, you probably won't notice it, but if you're trying to listen to the crickets, it could be bothersome.

Most of these timers are rated at 10-12 Amps for 120 Volt use, so at 12 Volts, will handle a hefty load.

My installation was on an interior hollow wall, the physical size requirements of a box could eat up valuable space in a standard tear...

Thanks for bringing these points to light!

Rob

[zapj]

Thanks for the info. I had thought of the 120v timers but because of size I was wondering about a 12v device. The expense does not justify the occasional need.

[Sonetpro]

I don't know how you are with electronic's but here is a schematic to make one.
http://www.uoguelph.ca/~antoon/circ/relay11.html

[zapj]

Hey Sonetpro, thanks for the hieroglyphics. With that said your question about my knowledge of electronics has been answered. I do have a nephew who dables in such things so I'll pass the schematic to him. Again thank you.

[GeorgeTelford]

Hi Rob

Most of these timers are rated at 10-12 Amps for 120 Volt use, so at 12 Volts, will handle a hefty load.

Not strictly true

12 volt DC switches need a a faster switching time than 120 VAC otherwise the contacts are likely to weld ON.

Make sure that any switch you use is rated for DC power as well, it needs a higher spec than AC mains to ensure the contacts dont weld.

[48Rob]

Hi George,

Thanks for the tip.

I've never had that trouble, but if I do, I'll know why.

Rob

[Sonetpro]

If you're switching DC it's best to use relays. You could make a circuit that uses AC control to switch a DC relay