Using an AC-to-AC wall wart transformer/adapter in reverse

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On 2/8/2009 4:13 PM Ralph Mowery spake thus:
>

As pointed out, at a low frequency like 60 cps*, DC resistance impedance to a good first approximation (in other words, close enough for gov't. work).
* Cycles per second, the true measure of frequency. What's this "hertz" bullshit? Since when did a car-rental company come into the picture?
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wrote in message >>

When the reactance is 3 or more times the DC resistance that is nowhere near enough for gov't work. The coil will smoke if you use the DC resistance even at 60 cps. if the power supply will put out the current.
Oops , forgot about the big bailout going on now by the government and the big crash that is going on now. That banking and loan calculations were good enough for gov't. work. It smoked too.
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On 2/8/2009 4:44 PM Ralph Mowery spake thus:

Nonsense.
Don't believe me? Get ahold of an 8 ohm speaker and measure the resistance (DC resistance) using a DMM. It'll be within 10% of 8 ohms, which is the rated *impedance*. And this covers the audio spectrum (up to 20 kHz).

It's a figure of speech, my man.
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On Sun, 08 Feb 2009 01:10:22 -0600, Matt

Get one. They are very common, plentiful, and cheap. If you were in Kitchener Waterloo I'd GIVE you one.
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snipped-for-privacy@snyder.on.ca wrote:

Shucks, I wish I were there ... but would it handle say 20A @ 120VAC? To run a heater. I just paid $20 for a 30A relay, waiting for it to get here ...
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On Sun, 08 Feb 2009 19:18:20 -0600, Matt

No, it is rated at 15 amps, I think.
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On Sat, 07 Feb 2009 17:23:32 -0600, Matt

Yes you can, but keep in mind they are only something like 80% efficient at best, and your maximum primary current will be the rated output of the device. This means a 1 amp wall wart will put out 100ma of current at 120 volts from a 12 volt supply.
In an AC wall wart there is only a transformer. Don't try it with a DC output unit though!!!!
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On 2/7/2009 3:23 PM Matt spake thus:

You might be interested in this guy's pages:
http://www.dogstar.dantimax.dk/tubestuf/index.htm
He builds vacuum tube circuits, and some of them are powered by 2 wall-warts back-to-back, just as you're asking about, like this power supply used for one of his projects:
http://www.dogstar.dantimax.dk/tubestuf/sappower.htm
This circuit supplies more than 400 volts of B+ for a small tube amplifier (using a voltage tripler), as well as several other voltages. So yes, it can be done.
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On Sat, 07 Feb 2009 17:23:32 -0600, Matt

    You know of course that it can only handle very small current levels and that it would need the original output circuits would will be handling 120V when they are only insulated for 12Volt
    In short, it is a bad ideal Get the right tool for the job.
    Joseph E Meehan
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On Mon, 09 Feb 2009 08:27:26 -0500, snipped-for-privacy@hotmail.com wrote:

You are mis-reading him. The low voltage goes IN the low voltage side, making the high voltage go out the high voltage side so everything is operating within it's design parameters insulation-wise.
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Yes, and AC output wall wart should provide the needed voltages. However, we don't know if the application would work just fine. How many watts of 24 VAC do you have, and how many watts of 110 VAC do you need?
Should be able to convert 24 VC to 110 VAC. You won't have much amperage to use, on the 110 VAC side.
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