12VDC: Can it drive a thermostat "rated for 24VAC usage"?

some back and forth about whether or not you can use a 24V AC thermostat by powering it with a 12V DC wall adapter.

Any thoughts? I'm electrically challenged.

Glen

Reply to
Glen Leslie
Loading thread data ...

some back and forth about whether or not you can use a 24V AC thermostat by powering it with a 12V DC wall adapter.

Any thoughts? I'm electrically challenged.

Glen

Reply to
Glen Leslie

formatting link

I'll say it will work. It's basically a set of contacts, no electronics involved.

Reply to
Chris Pflieger

some back and forth about whether or not you can use a 24V AC thermostat by powering it with a 12V DC wall adapter.

Any thoughts? I'm electrically challenged.

Glen

Reply to
Dr._Flouride

...

The "son of a fermentation chiller" uses a plain old analog, mercury switch type thermostat in the design. There's nothing 'powered' in that type of thermostat so AC/DC doesn't matter. That thermostat is only a switch and the current flows thru the mercury/bimetal switch inside. So......

Ratings wise, you are only worried about too much CURRENT (at ANY voltage) going thru the switch (and other wiring inside) and melting something! :) The design of the "SoaFC" uses the thermostat switch to control a small DC computer fan which certainly doesn't pull too much current for the thermostat.

NOTE - you have to match the fan you're using with the AC power adapter you are talking about. IE., you can't use a DC fan with an AC power adapter that transforms to AC, nor can you use an AC fan with an AC power adapter that transforms to DC.

Again, note, SoaFC is talking about a plain old mercury switch type thermostat. Do NOT try to switch DC/AC on a "smart" thermostat... it won't work because those thermostats need the DC to run their electronics. ((Mercury switch thermostats don't have electronics like that)).

That website discusses all this pretty well in the section "About Thermostats."

Derric

Reply to
Derric

readely find. It would either be rectified from a wall outlet(120V AC 60Hz) or amplified and modulated from a lower voltage DC source such as a battery. Generaly a thermostat is a somewhat linear resistive device which would probably operate best on DC, but could be made to function on either source depending on the engineering done to create the display you would look at for deciding what the temperature of the sensor was. If you use DC to make a resistive sensor its pretty straightforward, but if AC is used all these different variables come out to play such as inductance and capacitance changing the equasion you're electronics are trying to run...

rendering it useless.

Chiller

formatting link
there's some back and forth about whether or not you can use a 24V AC thermostat by powering it with a 12V DC wall adapter.

24 VAC is readily available from a transformer available in most electronic supply stores. probably even from Radio Shaft! 110-125 VAC in = 24 VAC out,

AC is never rectified unless you are looking for DC.

I switching power supply converts mains voltage to DC, then provided square wave oscillation to drive a transformer to produce another AC voltage which is then rectified to provide DC.

If you need 24 VAC, get the transformer. DC cannot be used to drive an AC item. If you need help, ask one of the neighborhood techies who will probably more than gladlyhelp you out for a couple of glasses of suds...

RadioResearch

"Fuck 'em all but nine. Six for pallbearers, Two for roadguards, And one to count cadence." old Army toast

----== Posted via Newsfeed.Com - Unlimited-Uncensored-Secure Usenet News==----

formatting link
The #1 Newsgroup Service in the World! >100,000 Newsgroups

---= 19 East/West-Coast Specialized Servers - Total Privacy via Encryption =---

Reply to
RadioResearch

I'm more confused now. Can someone just answer 'yes' or 'no'? Will the adapter work with a digital thermostat? I got a digital thermostat for free from my parents. Should I get a more basic one?

"RadioResearch .com>" >

would readely find. It would either be rectified from a wall outlet(120V AC

60Hz) or amplified and modulated from a lower voltage DC source such as a battery. Generaly a thermostat is a somewhat linear resistive device which would probably operate best on DC, but could be made to function on either source depending on the engineering done to create the display you would look at for deciding what the temperature of the sensor was. If you use DC to make a resistive sensor its pretty straightforward, but if AC is used all these different variables come out to play such as inductance and capacitance changing the equasion you're electronics are trying to run...

off, rendering it useless.

Chiller

formatting link
there's some back and forth about whether or not you can use a 24V AC thermostat by powering it with a 12V DC wall adapter.

Reply to
Roger Dubet

Just try it. It will either work or it won't. If it doesn't, reverse the DC polarity and try again. If it still won't work get a 24 VAC adaptor.

Reply to
Chris Pflieger

Yes, it will work. Period.

I have a 12V computer supply fan (torn from an old pc) with a 12V AC/DC power supply (the kind with the big square part that plugs in the wall.) It's wired to a $8 thermostat (cheap one from Home Depot) and it works just fine. One of the previous posters is right, what matters is that you match your fan's required voltage with a proper power supply. The fan will have what it required printed on it somewhere, just find a power supply to fit it. I tore an old power supply off a old print server, cut off the round end, attached the wires according to my thermostat's instructions, and off I went.

Reply to
Xiejol

The answer is a resounding NO!

If the adapter and the device do not match then DO NOT PLUG THEM IN. You will very likely either destroy the adapter or the device. Not only should you not use an adapter of the wrong voltage, but using a DC adapter in an AC device is crazy.

Go to radio shack and ask them for an adapter that has the exact same output as the device requires. If they don't have it look for on from a store on the web or some other place that sells them in your area. 24VAC adapters are actually quite common.

Larry

Reply to
Larry

I have to agree Larry, I tried my 12v adapter with my digital thermostat. The fan spins but the thermostat didn't work. I went to Radio Scrap and found a 24v adapter. It's $35. I haven't bought it yet but I probably will.

Reply to
Roger Dubet

I use an analog thermostat for the very reason that it doesn't matter if it's AC or DC. Not to mention the fact that it cost $8 and saved me quite a bit over a digital model.

Reply to
Xiejol

DrinksForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.