New Iron Shipment!

[CJ]

Name that transformer: :grin:

http://vacuumbrain.com/The_Lab/TA/Telefunken/winston_iron.jpg

Re-wiring a V72 choke for a friend.
I was blown away by the lams used. Took me an hour to figure out how to take that choke apart. The lam is one piece! You have to bend it carefully in order to lace up the coil. There is an air gap of about 0.020 between the center leg and the E lam. I guess the reason for doing it this was to make certain that the gap never changed with time. Pretty clever. Realize that the gap does not go all the way across the lam in this situation. Only the center bar.

No, I do not think you can buy this lam anymore. Supposedly M6. Weird blue tint. Probably something to do with the insulation coating process. Ollie don't wanna say nuthin about it.

Once the coil is laced up, there is tension between the lams and bobbin due to the slight bend that you have to put on each lam to get it thru the bobbin tunnel. The tension from each lam adds up to a pretty hefty force, so if you take apart your V72, be careful with that choke! If the lams slide up 1/8 inch on the bobbin, POP! They will spring out a bit and you will have to fight to get them re-oriented. As I said many a time, so far each transformer I have taken apart has had at least one thing different than the others. This choke has many things different!


http://vacuumbrain.com/The_Lab/TA/Telefunken/v72choke_lam.jpg

 

[soundguy]

I thought you already hacked an am16?

dave

 

[CJ]

The AM-16 was my first X-former reverse job. All I did was take some measurements and them send them to Brian.


Here is the lam for the V72 input. 625-EI.

Another mind blower. Check out the "mother of pearl" finish. Never seen that either:

http://vacuumbrain.com/The_Lab/TA/Telefunken/v72output_lam.jpg

 

[soundguy]

are you opening those up? Would be pretty crazy to know whats inside there but even cooler would be a good comparison to the transformers on the altec 9470.

dave

 

[CJ]

What's on the Altec?

DCR on the Tele choke is 11.99 K ohms.

 

[soundguy]

Im not too sure, they are in a larger case than the am16 and sound a little beefier but very similar sounding. I would love to know what the deal is, wether they are so similar sounding because of some similarities between a fully balanced circuit and how that drives a transformer or if its just other commonalities with the output transformer.

dave

 

[adrianh]

CJ

You are getting old dude.

Remember this doc?


Try it.

OK for everyone else.
Please do not pester the source of this document.
It uses copper sulphate to identify steels used in transformers.
Now I got your attention right.

Remember copper sulphate is very soluble in water.
I would use distilled water and place the copper sulphate
in the solution till the solution will not hold any more.
Add a little more copper sulphate to the plastic container
and cap it tightly.

Copper sulphate is the bright blue crystals sold to kill algae
in ponds. Drug stores and good farm supply and fish stores will have
it.

OK for the legal stuff.
If copper sulphate will kill algae in a large pond then it may not be good for you! If you do not know what you are doing do not do it.
Dangerous things were placed on this earth to reduce the population!
Anything misused will harm you!

 

[CJ]

OK, 20,236 turns on the choke.
A nice bump at 12.8 k cps. Self res at 26 k cps.
700-800-- henries.

PRR method works for chokes too. I wrapped 20 turns of wire around the choke to get the turns via signal generator and scope-----ratio math.
Divide the in signal by the out signal and multiply by 20.

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72choke_prr.jpg

 

[mikka]

Wow..... serious choke. :shock: Thanks CJ for your time, effort and sharing nature.

 

[rafafredd]

CJ, what´s the DCR of the choke?

 

[EZ81]

[quote author="CJ"]

I was blown away by the lams used. Took me an hour to figure out how to take that choke apart. The lam is one piece!
[/quote]

Hi CJ,

that kind of lam shape is very common over here (for PTs, too) and is called M shape (as opposed to EI shape).

[quote author="CJ"] Ollie don't wanna say nuthin about it.[/quote]

Maybe try asking Ingo at shinrock.com...

;Matthias

 

[CJ]

Cool Mathias.
If you know of a lam vendor over there, that would be even more cool.

Raf is winding up a Tele choke right now, I can hear the winding machine! He want's to know when to stop. I guy who likes iron, a man of my heart!


, DCR is 11.99 k ohms.

 

[CJ]

Did a freq sweep on the V72 input. Has a bass bump which I see once in a blue moon. This is with 100 ohms in each leg coming from the generator, so I know it's not All resonace with the test equipment. Strange.

Anyway, self res at 41 k cps, ;blah blah blah

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_freq_response.jpg

Here's a phase shift chart. Used inverse sin method on x-y ellipse on scope. Strangeness again-usually phase shift goes from lagging in the bass to leading in the high end. In this case, both shifts were leading. As usual, major shift near self res.

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_phaseshift.jpg

When I do a sweep test, I have to constantly adjust my generator's voltage knob to keep the same signal level that feeds the input of the x-former. . I noticed that different x-formers drag different amounts of current at the two frequency extremes, bass and ultra-sonic. So I came up with the bright idea of graphing current draw while sweeping the frequency. I have never seen a chart like this before, so you guys are probably the first to see such a spec. I guess I could invent a new spec, like microamps/cycles per second, etc. If Vanderdeen over at Plitron can get away with inventing his own spec, ....

anyway, here is the graph. I can't wait to collect additional current draw data from different x-formers. I should have done this a long time ago, as microphones are not known for being super stiff sources of current, so knowing what it takes to drive a transformer at the two extremes might shed light on why some models sound different. That current draw chews up your valuable mic signal.

Notice that the transformer is drawing zero current durring most of the audio spectrum. This is part of being a "perfect" transformer, that is, waisting no power.
Current is measured in microamps on this chart:

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_current_draw.jpg

Here are a few square wave @ 1 k cps shots, all un-loaded. Tried the stock 600 k, dosen't do much to the ring. Maybe neg feedback does.

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_1khzsq.jpg

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_1khzsq_1.jpg

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_1khzsq_2.jpg

Does pretty good on the sawtooth also. What ever that means:



http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_1khzsaw.jpg

OK, now the fun part. B-H curves and mag current/ satuturation levels.
Oh, and then a re-lam with some Super Q 625 EI to see how close it is to the rocket scientist's material.

 

[mikka]

Re: Mother of Pearl....... could this be some type of Mica coating?

 

[EZ81]

[quote author="CJ"]Cool Mathias.
If you know of a lam vendor over there, that would be even more cool.
[/quote]

Maybe http://www.waasner.com/. I doubt they want to sell you less than a few tons, though... :shock:

;Matthias

 

[CJ]

Thanks for the link, Mathias!
I might send you over there to do a little dumpster diving.

Mikka, it is ingrained in the lam, whatever it is. Could be cobalt.

I did some B-H curves on the V-72 input. Then I re-lammed it with some magmet Ni.

Interesting results. Here is a B-H at 10 hz sine wave with orig. lams, followed by the magmet lams:



http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_sat_sine_10hz.jpg


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_10hz_magmet.jpg

Frequency and phaseshift did not change much with the magmet lams swapped in place of the originals, but the input current did at the low end. The original lams were more efficient. They drew less current, probably due to the cobalt in the alloy. But at about 1 hz, the cobalt started drawing more current. Here is a comparrison. The magmet plot is in red.

This means a little bit better bass with the Telefunken lams:

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_bass_current.jpg

The coil assembly came apart in disks. I do not know if the individual disks were wound first, varnished, then assembled on the coil former with those brown plates inbetween. or if the 6 coils were all wound at the same time on the former with a multiple winding machine. Lack of varnish on the brown seperators has me guessing that they were pre wound:

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_coil_6.jpg

Here are the individual coils. The silver ones are the primaries. They were sprayed with some type of metalic paint. This is for shielding. Pretty strange:

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_COILS_1.jpg

Here are some more pics:

http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_coil_2.jpg


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_coil_7.jpg


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_coil_9.jpg

Here is the shock absorber/tensioner on the pressboard former:


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_coilform_1.jpg

Here is a close up of one of the primaries:


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_PRICOIL_2.jpg


http://vacuumbrain.com/The_Lab/TA/Telefunken/V-72/v72input_PRICOIL_3.jpg



Now where are those Langevins! (chops a drollin..)
:guinness: :guinness:

 

[mikka]

Re: The spray, I assume they used some spray nickel..... but was it wired in to earth? If not, could it be just colour coding for P and S for the assemblers?

 

[CJ]

Wired to earth and the bottom of the secondary.
cj

 

[gyraf]

Wow... :shock:

 

[mikka]

Echo on that......... :shock: :shock:

A big thank you CJ for your efforts. These mofo's are fascinating to learn about.