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

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!

24 Replies

user
steveastrouk (author)2014-12-11

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

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user
atkers (author)steveastrouk2014-12-11

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

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user
steveastrouk (author)atkers2014-12-11

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

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user
atkers (author)steveastrouk2014-12-12

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

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user
iceng (author)atkers2014-12-12

Are they to be 24 HR repeating timers ?

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user
atkers (author)iceng2014-12-13

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..

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user
steveastrouk (author)atkers2014-12-13

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.

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atkers (author)steveastrouk2014-12-13

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?

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atkers (author)steveastrouk2014-12-13

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.

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user
steveastrouk (author)atkers2014-12-13

Still looks like a mechanical one to me.

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user
atkers (author)steveastrouk2014-12-14

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

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user
atkers (author)steveastrouk2014-12-13

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.

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user
steveastrouk (author)atkers2014-12-12

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

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user
atkers (author)steveastrouk2014-12-13

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

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user
iceng (author)2014-12-11

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

AC, DC, voltage, current ???

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user
atkers (author)iceng2014-12-12

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

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user
iceng (author)atkers2014-12-12

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

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atkers (author)iceng2014-12-13

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

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atkers (author)atkers2014-12-13

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

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user
iceng (author)2014-12-12

You don't have any idea what current ?

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

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user
steveastrouk (author)iceng2014-12-12

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

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user
iceng (author)steveastrouk2014-12-12

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

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user
steveastrouk (author)iceng2014-12-12

I can't remember the number.

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