Need help on a timer circuit design. I'm an idiot at IC design. But, I can solder.

I need a timer that does this-
When DC 12V power is applied to Input 1 it starts a timer (timer needs to be variable from 1 to 10 minutes) during this time DC 12V is outputted on Output 1. When timer completes no voltage output on Output 1.

Note- Power will continue to be applied to Input 1 after the timer completes.

Application -> when water flows through a Magnetic Water Flow Switch the circuit is closed that switch & voltage from a battery is connected to Input 1. When water starts flowing through the pipe I want the timer to start which applies voltage to a flow control valve which opens a valve.
Whats happening is water is flowing into a water storage area which gets dirty very frequently. There is a drain on the bottom of the water storage container. So water starts going into the water storage area the drain valve opens and basically clears out the dirt. After a few minutes the storage area is clean the drain valve closes and water continues to flow until it's full.

If someone can help me with the design or point me to the design schematic somewhere on the internet that would be very helpful.

 

I was pointed to this listing on ebay - http://www.ebay.ca/itm/DC-12V-Multi...222133?hash=item3f51f92535:g:bEcAAOSwsTxXjEXG
I think Function 12 is what I need-
[Function 12]
Trigger timing mode B?the relay does not operate after power on ,give IN1 interface
a low pulse signal, the relay pull-in , when arrived the timing time T1, the relay
disconnect,T1 can be adjustable between 0.1 second -270 hours, give IN1 interface
a low pulse signal again, repeat the above function one time.

It's asking for a low pulse signal on IN1 - How would I go about doing that? The Input signal that I'm working with is either on or off.

Thanks - very helpful responses

 

There are many kinds of timer modules available on ebay. Are you looking for advice on which one to buy, or do you want to build a timer circuit from scratch?

Also, what is the current you want to switch at 12 V?

ak

 

As I have all parts on hand, I'd go the old faithful 555 route triggering on power-up, timing with 1 meg. pot
in series with about 75k & 1000 uF cap. Use either N ch FET or transistor for valve driver.

 

http://www.electro-tech-online.com/threads/timer-curcuit.148832/

post #9.

ak