500VA Variable Auto Transformer

I bought this to control the voltage of my guitar amps and it does the job well. The viltage regulator is accurate from 0-130VAC, with a 5A fuse. Its heavy and built well.

the VU meter matches the dial labeling but nether of those match actual output voltage. the dial is labeled in increments of 13 volts and for every increment +1v or +2v is added to the actual voltage so at 13v dial setting I get 15v, at 26v dial setting I get 30v, etc. at 130v dial setting I get 148v output. output spikes -1.3v at max output (148v) and -0.6v at near min setting (2v) periodically (~2hz, smooth spike). aside from this spike voltage is +/- 0.1v for about 70% of the time, the other 30% being that spike happening. attached is a multi meter test for the dial sweep. dial was turned from min to max to min at a more or less constant rate a few times. voltage spike happens with my unit at around 25v and its significant. you can see it in the picture. the rest of the transition from min voltage to max is smooth. scale of the graph is 0v-160v mean is 80v. also attached is oscilloscope reading of the output at 2v. my scope is only rated for 10v max and im not going to push it with this unit. shows 60hz +/- 0.1hz with a periodic spike in hz every so often which makes it dip to sub 20hz. spike is super short (a few microsecond or less is my guess, didn't bother to try and catch it on the scope to measure it explicitly.) and happens less than once per second so no big deal. you can see that spike measured in the statistics frame on the oscilloscope image under the Min column, average column is still close to 60z so its not a significant spike. if you care about a spike that short you probably care about the waveform too - scope shows a pretty clean saw waveform, not sine wave. this aint guna be lab gear. all in all, for the price, its fine. its not supposed to be lab equipment and as long as you mind the actual output voltage it should work well. im pretty happy with it. UPDATE: been running 24/7 for 11 months, no issues at all.

Works as described - just be sure to check the AC output for fluctuations as this is AC so incoming power affects the output

I just received the unit, and checked the voltages using a multimeter. It delivers a different range than what is shown on the unit. Rather than 0 - 130 VAC it delivers 0 - 150 VAC. I recommend calibrating and putting your own markers using tape so you know what you've got. For example, to get 100 VAC, 110 VAC, and 120 VAC I need to set the dial at around 88, 96, 104, respectively. My wall voltage is 123.4 VAC, so that might be part of the issue -- the unit might be expecting a wall voltage that is lower. But in any case, you should calibrate this according to YOUR home voltages.

Easily the best option when bench top supplies don't cut it. If you're at the point where it's impractical to keep buying larger power supplies, you need one of these. Frankly, they are just awesome. You get a massive range of voltages to play with, and best of all, it's AC! Seriously, this expands the range of devices you can power immensely. And not just Microwave Oven Transformers. But those do totally work 😉. The thing even has about half a Henry of inductance at full tilt, and does hum pretty good if you're pushing the rated power, but personally I consider this an audible saftey feature 🤷. Built pretty good, replaceable fuse slot is nice. Yeah, buy one imo. Makes the wall socket somewhat less scary, and that's pretty great

Using for vintage audio troubleshooting. I haven't bothered to check the absolute accuracy of the voltage, I run this from an isolation transformer into a dim bulb tester and had no problem getting the responses I was after. Well worth the bucks. The actual Variac brand name is absurdly priced. I need AC voltage input to check from the transformer forward. I'd buy it again.

I use this to adjust an air mover/blower to bring it down to a whisper. It's incredible how quite you can get a blower to be when you get it down to 40V or so, and it still moves a ton of air. This variac did get warm and burned in a divot spot when left for a long period of time in one position with a high watt blower though, so I recommend verifying that your motor wattage is low enough for this to handle, and maybe get one rated for higher wattage if you want to keep it running long term.

Arrived in perfect shape, with a pack of extra fuses. Haven't needed one yet. This sort of variac is only useful in some very slim scenarios, for relatively few things - particularly, controlling the speed of certain types of motors (shaded pole, and maybe universal), or the brightness of certain types of lights (incandescent, or some LEDs that are line-driven with no other intelligent power supply inside). Given its limited uses (and ways it can cause problems in inappropriate use cases), I expect people to frequently buy this thing for the wrong application. In my case, I bought this along with an inflatable projector screen - so I could control the speed of the blower and make it silent (and draw less power, as I'd be powering it on battery), while still keeping the screen inflated. Indeed, around 50% speed, the screen stays inflated and silent. Works great for fans and blowers!

El indicador de voltaje es muy impreciso, por lo demás excelente