12 Volt Timer Relay

Thanks for the novel response. I went with the Wolstentech relay. Bob

Thanks for the novel response. I went with the Wolstentech relay. Bob

www.wolstentech.com/products//timedelayrelay

Well you certainly have more experience than I do plus I have been out of practice for the past 20 years.

I have used a simple diode up to reversed zeners for snubbers or more elaborate setups for switching power supplies to eliminate RF noise I don't remember referring to the circuits we used as snubbers we just had to eliminate the arcing and RF.

I am not arguing or disagreeing with you I just did not think about it in this case due to low voltage and the application.

Garry,

Those timers must be used with a snubber in certain DC applications:

When the contacts open the inductive kick back from the motor will start an arc between the contacts.

Two things can happen.

1. The contacts will be eventually destroyed. :(

or

2. The contacts will be welded together. :(

The series RC (snubber) circuit slows down the voltage rise across the contacts, thus preventing the arc from forming. :)

Timers for bathroom infrared lamps are available as mechanical timers used in many hotels.

Can be used with 12VDC and available from Lowe's or Home Depot.

96Bounder30E wrote:
How about using a 15 minute spring wound timer?......cheap and plentiful........and it doesn't care what voltage you are running through it.....(12V DC or 120V AC)

I know that timer well, having been the Chief Test Equipment Engineer at Intermatic.

It will work rather well but when using it on a DC circuit you'll need a "snubber" across the leads.

----^v^v^v^v^v^v^v----|(----

The resistor is 47 Ohms 1 Watt and the capacitor is 1 µF @ 100 Volts.

The snubber is to kill the arc when the contacts open.

What's wrong with just watching the fuel gauge, then pumping ONCE when you need it?

If that's also a problem, reset your trip odometer every fillup, and use that as your gauge.

X2 what 96Bounder30E says...

Great to have around RV for things like that.

Roy Ken

How about using a 15 minute spring wound timer?......cheap and plentiful........and it doesn't care what voltage you are running through it.....(12V DC or 120V AC)