24VAC power supply

Nov 11, 2009 9 Replies

The Altronix ALTV244175ULCB Power Supply can be configured for 24VAC or



28VAC. However, when configured for 24VAC, a DVM indicates 27.8VAC at the power supply. If the specifications in the manual for a security device are, for example, 22VAC to 26VAC, would you expect 27.8VAC (assume relatively short run with minimal voltage drop) to work fine?

Best, Christopher


Yes. With few exceptions the equipment will function fine forever with a slightly high power supply. For example, the 24 VDC power supply for my laptop died and I just replaced it with a 26 Volt unit I found in the gar

Unless your meter reads "True RMS" (a function normally relegated only to upper-mid-range and better devices), you're probably getting a reading somewhere between RMS and peak-to-peak, whereas device voltage ratings are generally rated as "VAC RMS". 24VAC RMS is actually about

34V p-p.

Remember that your output voltage with a straight transformer will vary proportionally with the input voltage: if you have a 5:1 transformer,

120VAC input will give you 24VAC output, but 130VAC input will give you 26VAC out, and 110VAC in will give you 22VAC out. Since line voltage can often vary by 5% or more, expect your output voltage to vary accordingly.

As as you put a load on a transformer the voltage will drop also what your reading is voltage at no load.. which is always a litle higher.

Christopher,

I assume you realize my earlier post to this thread was in jest.

Reminds me of a common offline-reader tagline from the BBS days...

"Wow, that lightning was really cl$!@)~~**88 NO CARRIER"

Actually, it was a rip-off of old Gahan Wilson cartoon in Playboy. The drawing shows a sign painter lying unconscious next to a sign that reads, "Danger! Falling Roc" :^)

=BDThe drawing

Similar to a another cartoon

I think,..... therefore ....... POOOF!

Descartes' girlfriend: Would you like some coffee, dear?

Descartes: "I think not...." [pooof!]

I always thought it interesting how he phrased the famous quote. He didn't say he was somewhat certain that he existed. Rather, because he thought he was entirely certain that he existed somewhat. :^)

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