Mystery transformer

[beasleybodyshop]

So i have a bunch of mystery transformers that I scavenged from a garage sale. Of particular interest is one i have attached a picture of - It looks like it has a CT primary on one side and 4 wires on the other. Im hoping this is maybe a 15W or so output transformer. On the top of the case it says "CLASS 2" and then the numbers are 37-7943 and then 45579PI. looks like its paper layer wound, whatever that is worth.

Anyone have any info on finding out what this is? i dont recognize the color coding on the wires. I dont see any EIA codes i recognize.

[Leo_Gnardo]

So i have a bunch of mystery transformers that I scavenged from a garage sale. Of particular interest is one i have attached a picture of -

No photo mr beasley... try again. Heck let's see 'em all.

[gui_tarzan]

Yeah, make us jealous.

[Stevem]

I`ve got a EIA code list of 42 transformer manufactures and that code 37 is not one of them!
Class 2 may be a reference to CCS usage which would make it a PT and not a OT.
That would seem to be a 1979 era transformer, does what you think is the primary side have lighter gauge wires like a OT would have?

Pump some ac voltage in on whatever end you choose and see what the turns ratio seems to be ball park wise!

[beasleybodyshop]

Sorry thought I attached it!

[Stevem]

I got to say I that it really looks like a line matching transformer for a 70 volt PA speaker system!

[Phil_S]

Do a voltage test for turns ratio. Maybe you got lucky?

[eniam rognab]

i have a similar PT with three secondaries, and 4 primary wires. depending on how you hook up the primary: Nominal, -6%, +12% and +6 percent. Secondaries are a 48v 1A center tap, fyi...

yeah, try a little AC via a variac, and measure the secondaries.

good luck buddy!

[Cliff Schecht]

Take a picture of the bottom and post it. The thickness of the laminates is a telltale sign of what it's application is. Thicker laminates means it's for lower frequencies only, thinner laminates means it's meant to handle at least audio frequency. Since it's probably push pull you don't have to worry about the core gapping or being able to handle DC current in the primary side.

[beasleybodyshop]

Take a picture of the bottom and post it. The thickness of the laminates is a telltale sign of what it's application is. Thicker laminates means it's for lower frequencies only, thinner laminates means it's meant to handle at least audio frequency. Since it's probably push pull you don't have to worry about the core gapping or being able to handle DC current in the primary side.

Bottom has a cover plate over the laminations, so i can't see them but it appears the lams are thin.

Could i run 6vDC into the primary side and measure that? I found an old 6VDC regulated PS module in an old exhibit today, thought about using that.

[eniam rognab]

Could i run 6vDC into the primary side and measure that? I found an old 6VDC regulated PS module in an old exhibit today, thought about using that.

nope, sorry, has to be AC

6VDC will just look like a resistor to DC, nothing induced on the secondaries

[Cliff Schecht]

I use a low current signal generator so that if the voltages on the secondary end up ridiculously high and I shock myself, it's a light tickle instead of a heart-pounding ZAP!

And yes has to be AC, a transformer is based off of two completely isolated coils that couple to each other inductively. You have to have a change in flux in one coil to induce a change in the other coil. Putting DC on it will change the flux one way (meaning the secondary side will move momentarily as if it saw a step function) but then nothing will happen because the requisite continuous change in flux never occurs.

[Stevem]

Its rare that a PT has only one black wire and or no white on its primary side!

[Phil_S]

If you have a PT with a filament supply on the secondary, that will do the job nicely for a test. Just screw everything down on scrap wood to keep it orderly and safe. You can use wire nuts or terminal strips. Soldering isn't necessary. You only need to turn it on just long enough to read voltages. If you can rig an in-line fuse, that's a good idea, but not essential. A surge protector with an on/off switch is handy and adds a bit of protection (mostly for your house, not so much for the device.)

If you use a PT with a high voltage secondary as the voltage source, remember to cap the high voltage wires and any other unused wires with heat shrink or other insulation. Be safe!

[beasleybodyshop]

If you have a PT with a filament supply on the secondary, that will do the job nicely for a test. Just screw everything down on scrap wood to keep it orderly and safe. You can use wire nuts or terminal strips. Soldering isn't necessary. You only need to turn it on just long enough to read voltages. If you can rig an in-line fuse, that's a good idea, but not essential. A surge protector with an on/off switch is handy and adds a bit of protection (mostly for your house, not so much for the device.)

If you use a PT with a high voltage secondary as the voltage source, remember to cap the high voltage wires and any other unused wires with heat shrink or other insulation. Be safe!

Thanks for the advice Phil, I will do some more discovery and report back.