Transformers (extreme n00b ahead - proceed with caution!)

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I'm thinking of doing something like the BrianGT kit and have a question about transformers.

Being on quite a low budget, I was wondering what kind of things I can rip transformers out of instead of buying them new. Stuff like microwaves and stuff. Is it rather safe for a n00b to be doing this, or should I just buy new ones?
 
um, "is it safe"? it's lethal voltage. you better do some studying so you know what you're doing.

if you mean will it work to use recycled transformers, then that's more of a "depends". you might want to look at transformers that are already made for audio equipment, like in discarded 70's receiver amps like technics, kenwood, yamaha.

the problem there is they tend to be center tapped, not dual secondary, and their voltage tends to be a little on the high side for gainclone use. but look around, you might have some closet queen that would be good to convert into a gainclone.

and i wouldn't touch a ******* microwave. don't they use a high voltage circuit? there'd be positively dangerous charge sitting in the capacitors, just like in a monitor. there are some things you don't mess with untill you're very experienced.

http://www.gallawa.com/microtech/safety.html
 
Uhuh, definitely no microwave oven transformers are going to be good for a gainclone. They are over 1000V and current limited, certainly not what you're looking for. Also, it's quite dangerous to muck around with one of these cantankerous subjects.

The best would be to look, as others have specified, in old receivers and the like, which have transformers rated for something within the confines of normal audio use.

They are mostly center tapped for use in split power supplies, but sometimes you'll get lucky and find something that will work in there. Just be careful and observant. A multimeter is your friend in telling what the transformer does.
 
poeee said:
I'm thinking of doing something like the BrianGT kit and have a question about transformers.

Being on quite a low budget, I was wondering what kind of things I can rip transformers out of instead of buying them new. Stuff like microwaves and stuff. Is it rather safe for a n00b to be doing this, or should I just buy new ones?


Don't get too hung up on transformers. Get a new one but there is no need to spend a ton. I've now built several GC's including one from BrianGT's kit and have used a variety of transformers.

You can get perfectly good sound and power from a 48VCT 3 amp transformer driving both channels. I have exactly that setup running right now.

Something like this- http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=120-225

(part number 120-225 in case the link doesn't work). I actually got a pair with similar specs at a local surplus store for $9.50 each.

Later on if you decide you need more power or happen into some additional cash you can install a different transformer.
 
poeee said:
I'm thinking of doing something like the BrianGT kit and have a question about transformers.

Being on quite a low budget, I was wondering what kind of things I can rip transformers out of instead of buying them new. Stuff like microwaves and stuff. Is it rather safe for a n00b to be doing this, or should I just buy new ones?


18V-0-18V 300VA Toroidal Transformer

That's the transformer that I'm using. 2 of them for my 6 channel GC amp. Jaycar can mail order, or there may be a shop near you. If AUD 70 is too much for you, you might be able to scrape by with the 160VA version at AUD 48.

Steve
 
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I use toriods from Harbuch.

http://ourworld.compuserve.com/homepages/harbuch/harbuch.htm

They are usually cheaper than Jaycar and made locally. They have an very large selection, every VA and voltage you could want.

The one Jaycar toriod I bought buzzes. I was probably just unlucky though, as I haven't read other people complaining about them.

BTW: I don't know what the postage costs are. :hot:
 
ofb said:


since we're on the topic, what electronic item *would* likely have a 18 or 20 volt dual secondary transformer inside? are these typical to anything?


yeah amplifiers, and another good one is UPS's (they even list the VA rating on the unit). But they have a single secondary, so you will have to find 2 identical transformers.

You could check the local flea market for old heavy amps I guess.
 
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