Variac suggestions?

[mattmcl]

I'm looking at this one. In building audio gear, would I ever have need for anything more?

FRYS.com | PHILMORE

 

[Zen Mod]

best Variac is Marc

but that one is good , too .....

 

[Osvaldo de Banfield]

Principally, you may need an isolation transformer, because some test will need work in the power supply (Most if it is a SMPS), and Variac isn´t isolated. You can add a bench power supply, dual, 30V 3Amper is usual and sufficient.

 

[Frank Berry]

500VA is hefty enough for most things. Go for it and have fun.

 

[tvrgeek]

I bought what I could get used off e-bay cheap. In a perfect world, I would sure add an isolation transformer for safety, but I don't live in perfect.

 

[avincenty]

I have buit all of mine with around 2 amp powerstat panel mount transformers. I have one with an isolation transformer 1:1 and a HV transformer 1100 ct. I use this one to power up old gear and as HV source for my home made curve tracer. I have two with cheap filament transformers to use as variable filament ac source.

 

[Frank Berry]

I found a nice isolation transformer at a local thriftshop. 250VA.
I paid $2 for it.

 

[scott wurcer]

I bought what I could get used off e-bay cheap. In a perfect world, I would sure add an isolation transformer for safety, but I don't live in perfect.

I just bought a new 500VA variac from Taiwan, it puts out 120 at a setting of 91 and goes up to 150V out. You need a meter but it was cheap. I figure it was "calibrated" at 110 or 100V

 

[aramps]

Question from a noobish dude. I recently found "a lot" of old autotransformers/variacs/dimmers from a theater I was pulling equipment out of. These are circa 1960 I think and giant (14" diameter I'm guessing) and are rated at 6000 W (there are some smaller ones rated at 2500W too). I am hoping to use them (well, one of them) for a test table but thought I should ask for insight into the process of hacking one rather than buying an off the shelf variac. What would I need to actually connect this to the mains? Am I wrong, or just crazy that this can work? Should I set up integrated metering or just mark it off based on observed levels? Any other thoughts?

Thanks!

 

[turk 182]

aramps
this sounds like a major score
depending on what the primary ratings are a line cord panel meter to monitor output voltage and current and an output recepticle you've got a major variable voltage source!
any make or model # on any of them ?

 

[aramps]

Hello Turk 182,

They are Luxtrol D6000 models. Rated (apparently) to 50 amps at 120.

I'm glad there's some potential for them because I did rather bust up my hand pulling one of them out of the dimmer rack!

 

[turk 182]

was this an old Strand Century dimmer?
i'm tempted to ask if your selling any of them but i'm afraid that shipping weight might make the whole idea unfeasable.well enjoy you luck dog !
have you worked out a wiring scheme for any of them

 

[aramps]

I don't know if this was part of a Strand Century system but I doubt it because I don't remember seeing any branding like that anywhere, not really part of my area of expertise though (the projection booth did have Altec/Century equipment in it, but from a different/earlier era).

I imagine shipping would be crushing (I'm guessing they are 40lbs a pop), am happy to look into it if you're interested in some. PM me if you want to follow up on that.

What would be helpful for me (and the thread) would be understanding what exactly it would take (e.g. what range/rating) to add a panel meter to monitor output voltage and current and what would be the best kind of "output receptacle" (like I said, I'm a noob.)

I get that output voltage should be a meter that runs from 0 to "some number" but I don't know if, given these apparently won't let you transform to a higher voltage, that 120V is "enough" or if, since I am interested in tube/valve equipment I should have a transformer in front of it and a higher voltage range on the metering end.

 

[turk 182]

aramps
the metering is optional it's nice to include but not ultimately needed. panel meters for a 0 to 120 vac or 0 to150 vac and current meters to 50 amps can get pricey.now without knowing just how many terminals you have on these (pic's would help) i expect a minimum of three(some can have many more which opens the possibility of higher input voltages as in 240v some can be even more complex if they where designed to be powered from a three phase feed) for the moment we'll assume you've got a three terminal type think of it like a big potentiometer one terminal would be the high side the other the low or common and the wiper the output your input voltage would go across the full winding your ouput would be wired as neutral to a common(one side of the full winding) the hot comes from the wiper.
as soon as i can replace my scanner i'll post some basic schematics along with a few options like meters and a homebrew current limiter in the mean time should you decide to experiment with these please be careful the poke you can get from these can be lethal!

 

[aramps]

Okay, finally back to this project (I do have the excuse of having a newborn in the mix). I don't have the ability to post pics right now, but there are 3 terminals, single phase rated at 120V 50/60 Hz 6000W max. The weight is about 46 or so lbs without any packaging material! I am selling a few on ebay to pay for shipping the rest of them out to me here in CA - (no link to avoid violating any rules about that stuff here). Shipping is pretty steep via things like UPS or even parcel post - I'm thinking about just putting them on a pallet and doing a partial truckload, actually.

When they finally get out here I'll be wiring up a testing bench with this, a little DC power supply converted from a old computer's power supply and a few other odds and ends (contemplating building a larger bridge rectifier just for fun).