Where to salvage transformers?

[Michael Allen]

I've got a lot of projects of various sorts (pedal, amp, hifi, etc.) that I need lots of transformers for. Different voltages and such and since i'm experimenting I don't want to have to buy new trannies for everything i do. Where have you guys had good luck salvaging transformers from?

I've ripped some good ones out of an old Tube TV. That's what i'd assume to be the best source. Old tube equipment.

[H4T]

I'm not sure how useful they would be, but I ripped about 6 or 7 transformers out of an old CRT monitor not too long ago.

Anything that takes or needs high or special voltages would need a transformer...TVs, monitors, heck, you can even find them in toys that plug into the wall (phones, alarm clocks, stuff like that).

Be very careful with these suckers, lol.

[Hal]

any wallwarts - dremmel them open to get to teh trasnformer.  You can sometimes get them cheap at a goodwill store or garage sales or even new for like $1 or $2 at surplus stores.

[Michael Allen]

Yeah I load up every time i go to a thrift store. Plug packs are useful for modding but only for stompboxes. What I'm looking for is more higher voltage stuff like 18, 24, 48, etc.

[petemoore]

Printer adapters...printers turn to P'sOS after a while, almost invariably outlast the adapter, the ones Iv'e gotten range from 30v to 36vdc output.

[Hal]

you can make a transformer of a certain voltage by using a couple...I think...

::thinks::

(120-24v)(12-120)(120-24)

that gives you 48v.

Actually, that might not be safe.  Running 240v at the primaries of a transformer rated at 120
idk.

[niftydog]

as you can see there are many sources of transformers - however, how useful they are depends on where they are sourced from.

Old, like real old TVs had huge transformers to drive the heaters. I've found these useful for re-winding my own custom, multi output transformers for building my own version of the Spyder (before I knew about the Spyder). Think hand cramps, counting to a million without forgetting where you are, tangled wires and a lot of cursing and you get the idea of what it's like to wind your own.

Old, like not so old TVs (and all computer monitors) are full of switch mode power supply inductors, transformers and RF chokes - what's the difference I hear you ask!? Well, it's like the difference between a hummer and a geo. They're both cars, but you wouldn't take your geo bush bashing and parking your hummer in a half-space might upset some people!

It's exteremely rare that these suckers are useful without major modifications. For starters, often they are designed for very high frequencies making them virtually useless for 60hz power applications. And, rarely can they be deconstructed without destroying them.

So, oils ain't oils, my friend. Look for transformers that can be salvaged from linear power supplies (ie; not switch mode) as these will most likely be recyclable.

[Paul Perry (Frostwave)]

Something that used top turn up regularly in skips outside demolished office buildigns, were power supplies for old office phone gear, these are metal boxes about 1.5 feet long & 6 inches square, with a hefty 48v transformer & rectifier.
The other classic source is burnt out HIFI amps from the 70s. There is bound to be a thrift that is keen to give you broken amps for a couple of bucks, otherwise they have to pay to dump stuff. (typically the outputs were shorted, the transistors then acted as fuses but the tranny is OK).

[Mark F]

I do the same as Paul & salvage old Hi-Fi's, have been for years. I also salvage Boom Boxes, old radios, etc. I recently got a set of old intercoms that had 3 germ. transistors each. They were so old that they used silenium(sp) rectifiers :shock: , I haven't seen them in years even in old equipment. Basically I take just about anything old apart & salvage what I can. I also get film & ceramic caps, discrete diodes, both signal & power, some chips, discrete transistors. All this besides transformers & bridge rectifiers for power supplies. Man, there is a ton of stuff to be salvaged in old gear. I find a lot of this stuff at garage & yard sales.

[Paul Perry (Frostwave)]

I do  I recently got a set of old intercoms that had 3 germ. transistors each. They were so old that they used silenium(sp) rectifiers :shock: ,

Let's know how the selenium rectifiers go as diodes in your next distortion!

[Peter Snowberg]

I was going to ask the same question. What is the Vf for selenium anyway?

With all that surface area you probably don't need a parallel cap to shape the highs.

[Paul Perry (Frostwave)]

http://yarchive.net/electr/selenium_rectifiers.html

Too  much info on selenium toxicity (too much for someone who a a child used to salvage them from aircraft target drone electronics & clean the protective pitch off with kerosene..)
Seems the voltage drop is about 2V. and it's one of the few diodes whose internal resistance can be adjusted by a spanner!

Just remembered where I saw a large stack.. a 1950s battery charger.
And yes, they DO smell bad when distressed.
A pic: http://www.theodoregray.com/PeriodicTable/Samples/034.2/index.s7.html

[brett]

Hi.

Actually, that might not be safe. Running 240v at the primaries of a transformer rated at 120
idk.

THIS IS NOT PROFESSIONAL ADVICE.  Having said that, running primaries at higher-than-spec voltages may not stess them too much.  They are designed to cope with abnormally high voltages and large transients.  Here in Australia, our 240V primaries have to pass a 2.5kV test.  I assume that in the US the test would be at least 1kV.  Now, I wouldn't run a primary at 2.5kV, but I might consider going past 240V.

cheers