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Old 20th September 2020, 06:46 PM   #1021
cal3713 is offline cal3713
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Zen, another question as I try to force myself to understand the circuit.

For the voltage source that's added to the signal in the ltsplice diagram. Will just directly connecting to V+ & V- of an amp board work?

(And sorry if this got double posted. I swear I submitted it earlier, but couldn't find it in any of the threads I post in.)
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Old 20th September 2020, 08:04 PM   #1022
Zen Mod is offline Zen Mod  Serbia
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V1 in lower pic in #1018 is AC signal source

preamp, CD, TV, phone, whatever

in mentioned amps , there is JFet buffer in place of V1

just general remark - xformers are AC realm beasts

toss enough DC on them, all you'll get is smoke
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Last edited by Zen Mod; 20th September 2020 at 08:06 PM.
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Old 20th September 2020, 08:16 PM   #1023
cal3713 is offline cal3713
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Thanks for the continuing education.

I was confused by seeing both the voltage source and the "IN" connection. I just got a testing circuit worked out on the breadboard and was able to directly show myself the effects of disconnecting various coils on volume. Super useful for pounding it into the dumb head.

As always, thanks for your patience and help. Super simple once it comes together...
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Old 29th September 2020, 03:07 PM   #1024
G600 is offline G600  France
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Some news on the SissySIT front.
It's finally outputting some fine music.
Adjusted a while ago, but waited for some iron to finish my preamp.
I must receive the finished front panel from Schaeffer in a few days.
Two blue LEDs to be installed, and bingo.

Thank you, ZM!

Click the image to open in full size.
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Old 29th September 2020, 05:54 PM   #1025
Zen Mod is offline Zen Mod  Serbia
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if you're happy, I'm happy

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Old 8th October 2020, 08:02 AM   #1026
pras1170 is offline pras1170  China
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I resumed work today, and continue to sell 2SK182ES 2SK180 2SK1058 2SJ162 2SK1530 2SJ201 LM350K MJ21194G MJ21193G MJ21195 MJ21196 MJ15025 MJ15024 MJ15015 MJ15016 THF-51N THF-51 If you need a transistor, integrated chip, you can contact and send @qq.com directly: 378632242@qq.com
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Old 27th October 2020, 10:40 AM   #1027
mbrennwa is offline mbrennwa  Switzerland
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As always, I am late to the party, and I apologize for not reading every single post of this thread -- it is simply too long.

I have been staring at the SissySIT schematic for a few days now. I don't get it.

The gate of the IRFP9240 at the bottom is driven by the input stage. The gate of the SIT on top is driven by the optocoupler. This looks like the IRFP is the active gain device, and the SIT is part of the current source, that follows the gain device. Shouldn't it be the other way round (SIT = gain device, IRFP = current source / follower)!? What am I missing?

Is there an overview / walk-through of the circuit somewhere? A link to this might be useful.
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Old 27th October 2020, 12:43 PM   #1028
Zen Mod is offline Zen Mod  Serbia
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optocoupler's bjt with cap in parallel is firm stick between two gates

signal from xformer is pushing and pulling one end of that stick

other end of stick, naturally, follows

plenty of talk and mumble in link posted in post #1 of this very thread : Most Greedy Boy, of them all... or (there is no) DEFiSIT of Papa's Koans - Page 62 - diyAudio
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Old 27th October 2020, 01:39 PM   #1029
mbrennwa is offline mbrennwa  Switzerland
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Hmmm, I screened through that thread, but couldn't find the explanation. I can see how the opto acts as a stick between the gates. If the current through the outputs tries to wander off, the Hall chips will tell the opto to fix the length of the stick in order to keep the current fixed. But if the stick is a proper stick, and the two ends of that sick follow each other, then I'd think that both the SIT and the IRFP are driven by the input stage in the same way. I would have thought the SIT should be the gain device that is driven by the input, and the IRFP should be the current source that follows the SIT. Do you see where my brain goes wrong? I don't.
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Old 27th October 2020, 03:41 PM   #1030
Zen Mod is offline Zen Mod  Serbia
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think M2, OS is simple mosfet PP source follower, biased with great sense of humor

now, just replace upper mosfet with SIT, move current senses to rails, so you can remove source resistors

simple as that ....... same stick used in M2 and in SissySIT
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