More Blood and Guts

[CJ]

This time the victim is a specimen from the Signal Transformer company. Where is it used? I don't know but it passes audio fairly well, so that is grounds for destruction! :razz:

The victim:

The p/n:

The freq plot:

The 5 hz and 10 hz ultra saturated B-H:

1khz and 10 khz respective sq wave ring tests.
Undamped secondary. The reason for the 50khz spike:

http://vacuumbrain.com/The_Lab/TA/Signal_Transformer/1khz_sq.jpg

http://vacuumbrain.com/The_Lab/TA/Signal_Transformer/10khz_sq.jpg

I will be in the operating room for the next hour.

cj

 

[Gus]

36v ct transformer. 120/36 about a 3:1 line output ?

 

[CJ]

Holy cow Gus, you got a catalog?

Lookin like a 2.6:1 output. Kind of a sleeper. Looks like a dumb power transformer from the outside, but now that I have it apart and the black goo off, I notice 625 EI (API output) 50/50 Ni!

And a nice healthy chunk to boot. 50 lams.

Taking coil apart now.

 

[PRR]

> Holy cow Gus, you got a catalog?

Fool. All of us of a certain age know what a "241" is. Great transformers. Dandy power, and a secret weapon in audio. Shame they don't make them any more.

Put a 10K load on the secondary and see if it damps the 50KHz. IIRC there is no problem passing 20Hz-20KHz dead-flat. Pretty flippin amazing for a split-bobbin winding. (You won't find anything tricky in there.)

But I think you can feed more than 3VRMS into a "36V" winding, at least above 50Hz, if you have a low-Z source (much less than 50Ω).

Measure bass response at 1mV. It will not be as good as at 3V, but will it hold 30Hz with a resonable source impedance? (Like 600Ω,)

 

[CJ]

Well blow me over with a windmill I just reversed a centertapped pwr transformer!
Oh well. Hey, it is darn flat for a pwr tranny. Maybe the shine on the lams is just barn roof material. Only gave about 14 henries for 1116 turns, so maybe not what I thought. Nice smooth B-H , thats for sure, but started dragging down the sig gen below 20 hz.

Yes, no tricks in the winding. Just back and forth, sec had 212 turns each.
Darn, PRR, your an hour late otherwise I do your tests.

Might make a good 6V6 SE output for giutar. I heard that Fender and others used less than high fidelity transformers so that they wouldn't blow up the speakers with low end. You get away with a cheaper speak and iron that way.



Next!

Hey Butta, ever tried one for audio?

 

[CJ]

Wait! I just found another one PRR.
I will try that test tomorrow.
(people keep sending me iron, gotta clean out the mailbox everyday otherwise I have to pick it up at the P.O.!
:razz:

 

[PRR]

> Might make a good 6V6 SE output for giutar.

I'be be thinking more like 1-Watt SE, like 6EM7 or 50L6. Unless you really like bent lows.

And you probably want a steeper ratio for plate to speaker than a 120V:36V job can offer.

But yes, no reason you can't use power transformers for audio. Even cheap ones have as much bandwidth as guitar needs. DC current would be a problem, except generic power iron is SO cheap (50VA isn't twice the price of 10VA) that you can just over-size the core and keep DC flux spread thin in the iron.

Figure a 120V winding as about 5KΩ around 50Hz and you will be in the ballpark. You will have to go down in source impedance to get better bass (or up to get less, as for an 8" gitar cab). Work out the ratio to get secondary impedance. If you don't need maximum power transfer, light loading improves treble response (it will be all inductance, not capacitance).

 

[CJ]

Holy Mackerel Andy, I hooked up another 241 up and found out that it works much better as a line output when using the 120 volt winding as a primary. Better bass of course due to more inductance, peaks undamped at 150 khz instead of 55 khz, which is easily swamped out to give the following sweep.
The dark green is the 120 as pri, the other two lines are 36 volt as pri and 30 k sec resistor.

I used 10 k per PRR on the green curve.

And this is a pwr trans, sheesh!:

 

[CJ]

Butta, you were the person who sent me those, eh?

 

[CJ]

Sheesh, Im losin it! Yes now I remember.

OK, who sent me the signals? Fess up!

Butta, there are 4 on evilbay for 20 bucks and a couple more same model, different paint for ten.

Five bucks a pop. UTC, kiss my arse!