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How can I modify a basic mains timer switch (non-digital) to work with DC?

DC timers are extremely costly compared to their AC counterparts and can be very complex.

I'd essentially like to modify one of these guys to work with DC, plugged in a circuit, instead of the wall outlet.

Here's an example of the timer switch stuff I'm referring to: http://www.dbjholdings.com/images/300x300/5022822160514-3-1.jpg

So... how can I do it? I'd like ot to accept a wide range of input voltage (12v to 32 but 20 to 32 would also work if it makes it easier)

Thank you guys!

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Those have motors in them which only run on AC. The cheap AC DIGITAL timers are more hackable.

atkers (author)  steveastrouk2 years ago

This is as cheap as it gets? It's like few bucks only :)

I've picked up digital ones for well under 10 bucks. And they can be modified. These can't

atkers (author)  steveastrouk2 years ago

Well, I don't want to pay over $5 each. There are DC timers for $5 anyway..

iceng atkers2 years ago

Are they to be 24 HR repeating timers ?

atkers (author)  iceng2 years ago

I need a clock with pins on them so it can be easily changeable. Isn't there a way to hack these timers? I can replace motors if necessary..

The motors are AC types, they are called synchronous motors, because they spin at exactly and always a fixed multiple of mains frequency, and then its geared down so that the dial turns once every 24 hours.

atkers (author)  steveastrouk2 years ago

Ok. What if I find one of these analog timers that work on a battery but without digital screens and buttons and all the stuff. Would it be relatively easy to get it turn on/off a DC circuit?

Got a link ?

atkers (author)  steveastrouk2 years ago

Sure! http://www.ebay.co.uk/itm/NEW-24-HOUR-PROGRAMMABLE-TIMER-FOR-UK-MAINS-WALL-HOME-SOCKET-PLUG-IN-SWITCH-/360923541348 this one says it needs a battery to run.

Still looks like a mechanical one to me.

atkers (author)  steveastrouk2 years ago

steveastrouk well, I'll take your word for it. thanks for checking it out for me.

atkers (author)  steveastrouk2 years ago

Sure! http://www.ebay.co.uk/itm/NEW-24-HOUR-PROGRAMMABLE-TIMER-FOR-UK-MAINS-WALL-HOME-SOCKET-PLUG-IN-SWITCH-/360923541348 this one says it needs a battery to run.

$5 is "extremely costly" ?????

atkers (author)  steveastrouk2 years ago

Yes. I'm trying to hack things here :)

iceng2 years ago

After you have modified a timer what will it be used to switch.

AC, DC, voltage, current ???

atkers (author)  iceng2 years ago

It will turn on / off a DC circuit. I really need a DC timer :(

iceng atkers2 years ago

What AMOUNT of DCurrent @ 12-32 V DC ????????????????????/

atkers (author)  iceng2 years ago

It needs to be flexible if possible. I need varying amounts. (1x 24v, 1x,27v, 1x31.5v)

atkers (author)  atkers2 years ago

Current passing through will be 0.9a, 1.05a, 2a.

iceng2 years ago

You don't have any idea what current ?

Here you go, under $5.43 of components...

24hr4060-32vDC.JPG

Neat circuit. DIdn't there used to be 555's with the counter built on them ?

Recall something like that, Ill check my stock next time Im in back to the lab.

I can't remember the number.