variac variable transformer

[VictoriaGuy]

Originally Posted by Enzo

I use the variac in my shop all the time, an ammeter takes the place of a bulb. Either method works.

Certainly true in your hands, but for anyone 'starting out' the bulb does have the 'current limiting' feature that the ammeter lacks. Most days, I need my stuff to be idiot-proof, as much as possible.

Now, (belt, suspenders, and piece of rope dept) Variac, voltmeter, bulbs, and ammeter: SWEET!

Oh, yeah- don't forget to protect the Variac with its own (correct rating) fuse...

[soulmerchant]

My Regavolt 607-E is rated at 6A - its not a toy.

We have 230volt primaries here where I live.

[aardvarkash10]

6 x 230 = 1380W

No toy.

[Dagwood]

Come on, pics please???

[astouffer]

Originally Posted by TheGimp

I tried using a 2A variac once, and proceeded to blow the windings.

Best to use an over-rated one in case something shorts out.

Happened to me one time as well with a small variac. While taking some readings from an unknown transformer the 6v winding leads touched and spot welded themselves together. Before I could pull the plug a variac winding heated up and melted. It was right at the very start so soldering a new piece of wire was easy.

Dagwood: Yep thats about what I was thinking, except maybe having the lamps inside with a small hole to see the brightness.

[TheGimp]

I think my big variac is 20A. I have five or six I guess. If they are free, I'll take them every time.

[John Bessa]

My experience with my Sherwood 8000 (RIP) was that I constantly fiddled with ever-better sound. What I am thinking is that the variac (or other auto transformer) would be hooked up full time in case lowering (or impeding) AC input happens to improve the sound.

On that note, the last thing I did to the Sherwood was to cross-over point two small Jamo satellite speakers at the Yamaha Natural main speakers, which really brought things to life. Then it started making too much noise, I took it apart, found a mouse nest, and ultimately found that tapping a rectangular resistor caused the sound to change and then die completely and then come back, but that sound was distinctly different from the other noises so I figure there is a lot wrong with it. BTW, it's true about the voltages; when I was tapping around, my finger slipped and whammo, woke right up, and my finger felt like it had a vice grip on it!

So I am attempting to retrench with knowledge, which is taking a lot of imagination. Frankly, I am not sure any single (living) person actually knows how these things work in their full glory.

My project page: Wikiversity::HiFi

[boywonder]

Originally Posted by astouffer

I always wanted to make a variac test box that had meters for voltage and current and also switches to put in a 100 or 25 watt lamp. Maybe add a receptacle and also binding posts...

or this......

No lamp, but it also has variable B+ (by using the variac on the primary side of the PS transformer), variable bias voltage and 6V/12V heater binding posts.....The variac also controls the mains voltage at the receptacle.

[Enzo]

If the variac is melting under fault currents, where is the fuse?

Obviously one can go way too small on one and have it fail.

[Dagwood]

Hey Boywonder

That is one hell of a power supply!!!!

Great work, any chance of a pic of the inside?????

Cheers