Dirt Cheap General Purpose 12V Timer

Need to operate something for a period at the press of a button? It doesn’t get much cheaper or easier than this!

Available now on eBay for just AUD$12 (including delivery to your letterbox!) is this general purpose 12V timer. It’s ideal if you want to run an intercooler water spray for a short period at the press of a button – or do anything similar.

It’s adjustable for periods from 1 second to 3 minutes, comes with an on-board relay capable of running devices drawing up to 10 amps, is fully built and easy to wire into place.

The module was purchased from eBay seller: goodie310, located in Hong Kong. The part can be found by searching on eBay under “1s~3m Adjustable Delay Timer Module Entrance Automated Access Control PLC”.

The module

Measuring only 56mm x 26 x 23mm (L x W x H), the tiny module has a LED, relay and multi-turn adjustable pot. There are two terminal strips, one at each end. At one end there are the connections for:

·       12V and ground (don’t get them around the wrong way)

·       Trigger input

At the other end there are the relay connections for:

·       Common (x2)

·       Normally open

·       Normally closed

Viewed from underneath, the connections look like this. Note that when the being viewed, the ‘28mm’ written on the bottom should be the ‘right way up’.

Making the connections

The connections are dead-easy. Let’s say that you want to run an intercooler water spray pump for 30 seconds with just one push of the button.

Connect:

·       12V terminal to ignition-switched 12V

·       Ground terminal to the chassis

·       The two trigger wires to a normally open pushbutton (doesn’t matter which way around these wires go)

·       One side of the pump to ignition-switched 12V

·       The other side of the pump to the normally open relay terminal

·       The common of the relay terminal to the chassis

Like this.

Setting up

With 12V, ground and the pushbutton connected, you can easily set up the timer. When the pushbutton is pressed, the relay should click and the LED come on. When the timed period has finished, the LED goes out and the relay again clicks (as it switches off).

The multi-turn adjustable pot (arrowed) can be turned with a small blade screwdriver to change the timed period. As viewed from above, turn the pot clockwise to make the timed period shorter (and of course, anti-clockwise to make the timed period longer). 

Finishing

You can mount the module in a box but cheaper and easier will be to just wrap it in electrical tape or enclose it in large diameter heat-shrink. Do this only when you have the timed period set correctly!

Conclusion

Ah, the joys of eBay that put stuff in front of us that would have once cost four or five times as much…. If you do electronic car modification, at this price it’s worth buying one just for when you need it.