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I needed a 120v to 12v transformer, so I found these small DL 60 transformers on ebay. I hooked them up and turned them on, measured them with my DMM and got zero volts. I looked all over for documentation, couldn't find anything. Finally, I thought perhaps it needed a load before it would turn on. I hooked up a light bulb and lo and behold, it worked. So I measured the output and it still showed zero volts. It finally dawned on me, these weren't transformers at all, but switching power supplies! My meter read zero volts because it is expecting 50 or 60 hertz, not switching speeds.

Can't manufacturers label what their devices actually are?

I needed a 120v to 12v transformer, so I found these small DL 60 transformers on ebay. I hooked them up and turned them on, measured them with my DMM and got zero volts. I looked all over for documentation, couldn't find anything. Finally, I thought perhaps it needed a load before it would turn on. I hooked up a light bulb and lo and behold, it worked. So I measured the output and it still showed zero volts. It finally dawned on me, these weren't transformers at all, but switching power supplies! My meter read zero volts because it is expecting 50 or 60 hertz, not switching speeds. Can't manufacturers label what their devices actually are?

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[–] • 0 pt

eBay does that because they try to trigger on all keywords. Things like "Nixie tube" is applied to anything resembling a display tube. It catches the unwary, and makes searching for actual parts a pain in the ass.

A transformer is always going to output ACV, and I haven't seen a brick-type power transfomer in probably decades. If you do run across one of those, it's big and heavy. For the most part, you'll get open-frame or metal enclosed devices for component units, and sometimes wall warts for smaller currents. Anything that outputs DC these days is almost certainly a switcher, which you found out.

If you want an AC voltage, specify it in your search. "12VAC TRANSFORMER" The picture illustrates what I found searching for just that: https://pic8.co/sh/mPjWD5.png

Fun fact: 120 to 12 transformers can make an acceptable if inefficient test transformer for an AA5 radio.

[–] • 1 pt

That's the thing, it shows AC output.

Oh well, it works for my purposes. I was thrown off when my DMM was unable to read the output.

Ebay (ebay.com)

[–] • 2 pts

I see the data sheet for that device, it's a very special switching unit that runs at 40KHz. The reason it's called a transformer is due to it's specialty nature, that of a halogen lamp driver. That, most likely, is a leftover from an earlier age when those devices were actually iron-core transformers. They kept the same name because Jim Joe Bob Billy Sammy Allan Roger Junior wouldn't know what to do if he had to install a "Halogen lamp electronic power supply." It's like the Modbus protocol which calls it's inputs "coils" although there's probably not been a coil of wire used like that in years.

This device, while not ideal, is fine for incandescent and LED devices, but you're going to have a bad time if you're expecting 60Hz for something. Most devices expecting AC are going to reject that frequency.

[–] • 1 pt

Why's this fucking light always flickering!?