Disco Volante
Well-known member
85 laminations later and the bobbin is free. No signs of potting, varnish or wax, conveniently..
Who in (Germany?) made these? Valve rack units, small power amps and a mystery box
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Yes, because rust is non conductive, which helps reducing losses due to eddy currents.
Just looking back at the pics I think the extra box with the switches might be a bias oscillator,erase amp . Often the speaker output transformer is tapped to drive the record head on smaller more domestic style machines , Im guessing your modules come from a semi pro or pro machine , theres many manufacturers out there .
The label design might provide some small clue if you compare it to known makes of tape machine parts online .
The label design might provide some small clue if you compare it to known makes of tape machine parts online .
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zamproject
Well-known member
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- May 11, 2010
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Maybe just pyralene impregnated paper
zamproject
Well-known member
- Joined
- May 11, 2010
- Messages
- 1,592
Monsanto's trademark for polychlorinated biphenyl, or PCB
Last years a primary transformer for a 50' tube device (my Ondioline) get some short, arc inside and smoke... I open for fresh air, but inhale some, I was not feeling that good for few hours
Last years a primary transformer for a 50' tube device (my Ondioline) get some short, arc inside and smoke... I open for fresh air, but inhale some, I was not feeling that good for few hours
Disco Volante
Well-known member
Interesting comments. So I'm supposed to control my OCD and use the rusty laminations as-is?
Driving a tape-head would explain the high impedance drive, I guess, and maybe also the all-round focus on low noise and distortion (good components, regulated PSU, large-cored transformers).
I undid the first secondary winding. It did in fact have 1000 turns... or maybe 1050, I could have missed a few on the way;-) Could be coincidental?
The next section is a Primary winding, it looks like 0.15mm hairthin copper as specified on the label. I'm going to put together a coil winder for the metal lathe, I have a rev counter already so I just need a foot pedal and a wire guide. Using the manual slide and some sort of spring contraption for taking up the slack..
For want of "pyralene paper" (yikes) i thought I'd go with Kapton tape. It's floating somewhere in the vicinity of the 3D printer..
Now, a good look at some of CJ's amazingly documented transformer hacks and then to calculate the turns and gauge for the new coils.
Any other suggestions for a newbie? Or just RTFM, I can read a good amount of geek...
Driving a tape-head would explain the high impedance drive, I guess, and maybe also the all-round focus on low noise and distortion (good components, regulated PSU, large-cored transformers).
I undid the first secondary winding. It did in fact have 1000 turns... or maybe 1050, I could have missed a few on the way;-) Could be coincidental?
The next section is a Primary winding, it looks like 0.15mm hairthin copper as specified on the label. I'm going to put together a coil winder for the metal lathe, I have a rev counter already so I just need a foot pedal and a wire guide. Using the manual slide and some sort of spring contraption for taking up the slack..
For want of "pyralene paper" (yikes) i thought I'd go with Kapton tape. It's floating somewhere in the vicinity of the 3D printer..
Now, a good look at some of CJ's amazingly documented transformer hacks and then to calculate the turns and gauge for the new coils.
Any other suggestions for a newbie? Or just RTFM, I can read a good amount of geek...
Disco Volante
Well-known member
Given that they came from Denmark, it's possible they might be Lyrec components.
I have a set of transformers with the same purple foil on the outside, they came from a Siemens tube radio.
The laminations are called M, in contrast to EI. They were (rarely still are) mostly used by German companies as far as I am aware. They have the advantage of less leakage, tighter air gaps, and more winding space per core cross section compared to the standard EI cores. When the laminations were still widely produced they also could be bought with a specified air gap for DC applications. Disadvantage is cost because the two strips that are stamped out are waste, and they can only be stacked by hand I think. EI laminations are "wasteless", 2x E + 2x I form a rectangle without any scrap. They were also developed into a couple different forms to further reduce magnetic losses.
The laminations are called M, in contrast to EI. They were (rarely still are) mostly used by German companies as far as I am aware. They have the advantage of less leakage, tighter air gaps, and more winding space per core cross section compared to the standard EI cores. When the laminations were still widely produced they also could be bought with a specified air gap for DC applications. Disadvantage is cost because the two strips that are stamped out are waste, and they can only be stacked by hand I think. EI laminations are "wasteless", 2x E + 2x I form a rectangle without any scrap. They were also developed into a couple different forms to further reduce magnetic losses.
What tubes do you intend to use, at what impedance and which secondaries? What is the edge length of the lamination and how thick is the stack? Hifi/studio or guitar?
rock soderstrom
Tour de France
Me too, but I've also seen this color on Grundig and Telefunken transformers, if I remember correctly. It was probably hip back then...
Disco Volante
Well-known member
Volker, thanks, I guess this was good stuff back then;-)
The idea was 2x PCL86 in PP at 230V, Raa at 10k, 43% UL tap. Power not exceeding 10-12W.
The former measures 31x36x49 (copper side).
Lamination is 85 layers and 31mm high. The middle part is 56x29.
Application is hifi 20-20kHz. Secondaries 4&8 ohms.
The lams were a bit fiddly to remove, I can certainly see how EI would be more efficient in production.
I'm keeping the purple plastic! Wharfedale made some early dome tweeters from it. They sound awful partly due to the lack of damping under the dome...
The idea was 2x PCL86 in PP at 230V, Raa at 10k, 43% UL tap. Power not exceeding 10-12W.
The former measures 31x36x49 (copper side).
Lamination is 85 layers and 31mm high. The middle part is 56x29.
Application is hifi 20-20kHz. Secondaries 4&8 ohms.
The lams were a bit fiddly to remove, I can certainly see how EI would be more efficient in production.
I'm keeping the purple plastic! Wharfedale made some early dome tweeters from it. They sound awful partly due to the lack of damping under the dome...
Primary: 5200 @ 0,2mm
Secondary 4: 104 @ 0,8mm
Secondary 8: 147 @ 0,8mm
Of course the 4R winding would just be a tap and you continue with the 8R winding. Depending on what kind of interleaving scheme you want to do (I'll leave that up to you) I would rather go for secondaries with 0,5mm or 0,56mm and wire them in parallel. What I mean is, if you have a scheme like for example Pri-Sec-Pri-Sec-Pri you could make each secondary 147 turns with 0,56mm and put them in parallel. As opposed to having the two secondary parts in series with the fatter wire. The advantage of the thinner one is that it's more comfortable to wind and lay down and wastes less space. I wouldn't recommend anything more complicated than that scheme if you have never done that before, that's already plenty of wires flying around and it can get quite arduous at the end to connect everything correctly in a neat fashion.
That is plenty of iron for a 10W transformer and I specced it quite generously, it should turn out pretty good in terms of distortion and bass performance. I've never wound an M85 core, so the numbers I gave are more conservative and are definitely going to fit. My gut feeling says you should easily be able to scale up everything 5-10% without problem for even better performance, it's also a question of how tight and orderly you wind. Keep in mind the more interleaving seperation you do, the more space is needed for isolation in between.
If you wanted to reuse the 0,15mm wire it would be ok in terms of current capacity, just don't let CJ catch you doing it. DC resistance would increase from about 420R with 0,2mm to roughly 750R, still okay at the expected current (I assumed 25mA).
Secondary 4: 104 @ 0,8mm
Secondary 8: 147 @ 0,8mm
Of course the 4R winding would just be a tap and you continue with the 8R winding. Depending on what kind of interleaving scheme you want to do (I'll leave that up to you
) I would rather go for secondaries with 0,5mm or 0,56mm and wire them in parallel. What I mean is, if you have a scheme like for example Pri-Sec-Pri-Sec-Pri you could make each secondary 147 turns with 0,56mm and put them in parallel. As opposed to having the two secondary parts in series with the fatter wire. The advantage of the thinner one is that it's more comfortable to wind and lay down and wastes less space. I wouldn't recommend anything more complicated than that scheme if you have never done that before, that's already plenty of wires flying around and it can get quite arduous at the end to connect everything correctly in a neat fashion.That is plenty of iron for a 10W transformer and I specced it quite generously, it should turn out pretty good in terms of distortion and bass performance. I've never wound an M85 core, so the numbers I gave are more conservative and are definitely going to fit. My gut feeling says you should easily be able to scale up everything 5-10% without problem for even better performance, it's also a question of how tight and orderly you wind. Keep in mind the more interleaving seperation you do, the more space is needed for isolation in between.
If you wanted to reuse the 0,15mm wire it would be ok in terms of current capacity, just don't let CJ catch you doing it. DC resistance would increase from about 420R with 0,2mm to roughly 750R, still okay at the expected current (I assumed 25mA).
Disco Volante
Well-known member
Wow, thank you so very much. I was just getting into reading up on transformer math;-)
I have a bunch of 0.25 wire, would that work too? I guess it would take up a bit more space on the bobbin. I have 11mm winding depth.
I'll definitely take your advice on the secondary, I've made some speaker coils with thick wire and it's enough trouble even on a round bobbin.
When you say scale up everything do you mean in terms of wire thickness or also in terms of number of windings?
I think I should be able to make reasonably good windings with the lathe even if it takes a while.
Thanks again for your generous help
I have a bunch of 0.25 wire, would that work too? I guess it would take up a bit more space on the bobbin. I have 11mm winding depth.
I'll definitely take your advice on the secondary, I've made some speaker coils with thick wire and it's enough trouble even on a round bobbin.
When you say scale up everything do you mean in terms of wire thickness or also in terms of number of windings?
I think I should be able to make reasonably good windings with the lathe even if it takes a while.
Thanks again for your generous help
No, that would not fit, sorry. That would mean to reduce the primary turns to 4000 and a resulting B-field of about 1T. That's more guitar territory than hifi. I would use something between 0,15mm and 0,2mm. If you want to use something other than 0,2mm like I specified first, let me know and I run the numbers again so you can make use of the winding space in the optimal way.
I meant the turn numbers. But I just realized the original transformer had all the numbers and diameters on the little sheet. The resulting fill factor for the original is very close to what I calculated for 5200 turns, so I would leave it at that.
Disco Volante
Well-known member
OK. So 20% thicker wire means 20% less turns. Logical.
I'll just get some 0.2 wire. 0.5 for the secondary is readily available locally.
One more question:
In the datasheet Ia is specified at 40-42mA at 230V, 5K1 Ra.
Am I right in assuming that 25mA at 10k Raa equals 50 mA at 5kRa?
Given that each tube "sees" half the primary?
So ample powerhandling with almost 20% "headroom"...
Thanks
I'll just get some 0.2 wire. 0.5 for the secondary is readily available locally.
One more question:
In the datasheet Ia is specified at 40-42mA at 230V, 5K1 Ra.
Am I right in assuming that 25mA at 10k Raa equals 50 mA at 5kRa?
Given that each tube "sees" half the primary?
So ample powerhandling
with almost 20% "headroom"...Thanks
You're talking about a push-pull amp, right?
Each tube could be biased at 42mA if you wished to, provided the output xfmr can withstand the heat dissipated and the PSU can provide.
Half a 10k primary is 2.5k, AC-wise.
DC-wise, half a 420 ohm primary is 210 ohms.
What is your actual concern? It's not clear.
The recommended load for a push-pull of ECL86'swith B+ at 250V is 8.2kohm, so at 230V, it could be a little less, but it is relevant only to the maximum power.
https://frank.pocnet.net › sheets › ECL86
Disco Volante
Well-known member
Not really concerned, just trying to understand.
250V is stated as the max limit for PCL86, 230V recommended so a bit lower than ECL86 at 300V/250V.
Thanks volker, I get it! Who can you trust anymore, when even old datasheets can be wrong
Thanks guys.
250V is stated as the max limit for PCL86, 230V recommended so a bit lower than ECL86 at 300V/250V.
Thanks volker, I get it! Who can you trust anymore, when even old datasheets can be wrong
Thanks guys.
Probably because it allowed them to advertise an output power of 10W...
I don't think there is any structural difference between ECL86 and PCL86, except of course the heater. I reckon the differnces are due to manufacturers having different presentations.
You know that the EL84 is supposed to operate at a maximum of 300V, but many guitar amps operate at significantly higher voltages, up to 415V, which allows them to anounce a genuine 20W output. Of course, they are tube-eaters...
