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Old 29th October 2013, 01:57 PM   #11
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This is why I'll never understand electronics. This is a perfect example, even though it's such an easy schematic.

There's 100v going across the OPT into the drain, but "a signal is developed by the SIT at the drain".

Do people just accept this and don't ask why this works? Is it because electrons really flow from negative to positive? Is because there is an AC signal and the 100v is DC? I'll never get this stuff!
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Old 29th October 2013, 03:24 PM   #12
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It becomes easier to understand when you have separate abstract ideas of DC resistance and AC impedance. OPT=low resistance, high impedance. SIT=(virtually) high resistance, low impedance.

You actually don't have 100V across the OPT. You are connected to the 100V rail through the OPT but since the OPT has a small DC resistance it will only have a few DC volts developed across itself during idle. The SIT presents a larger effective DC resistance at idle so it develops the lions share of supply voltage across itself.

AC-wise, the OPT has (due to its inductance) a significantly larger impedance than the SIT so the OPT develops the lions share of AC voltage across its winding during operation.

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Old 29th October 2013, 03:38 PM   #13
Zen Mod is offline Zen Mod  Serbia
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Zen series of articles are jewel for sissy uninitiated ones , as me .

Some plumbing , some electricity ........ and just then you know how much you don't know

More Hendrix , more Zappa , more reading , more thinking

(that's my motto)
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Old 29th October 2013, 04:03 PM   #14
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I read all the articles. It doesn't stick.
Thanks for trying guys. I feel like idiot in your shadows.
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Old 29th October 2013, 04:15 PM   #15
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As 12B4 said, the DC "Iq" "Bias Current" is only seen by the DC resistance of the Xfrmr primary and the on condition of the SIT. Coils don't have much response to DC, only AC creates reactance. When AC signal comes along, the inductance developes much more "Impeadance" (AC Resistance) than the dc resistance in the primary. This inductance can actually develope more opposing voltage than the power supply is providing due to the current passing thruogh it, which gets transfered thru to the secondary.
Using inductors as a load for the gain device is a different circumstance and requires understanding of coils and such vs CCS or Light bulbs or Resistors.
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Old 29th October 2013, 04:17 PM   #16
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Oh, Yea, Mike,
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Old 30th October 2013, 02:00 AM   #17
12B4A is offline 12B4A  United States
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Do I need psychiatric counseling if I'm entertaining the idea of using a tube rectifier in the B+ supply?
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Old 30th October 2013, 08:00 AM   #18
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TV Dumper diodes ?
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Old 30th October 2013, 12:39 PM   #19
12B4A is offline 12B4A  United States
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Naw, 5V3A. After a good night's sleep, I think I'd go with SS diodes and TomCH's regulator choosing a slow start up resistor/cap combo. I just have so much fun doing SMD work...
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Old 30th October 2013, 12:44 PM   #20
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Damn, I was trying to pull my finger out and do something very similar for the output stage, but with a input/driver rather than transformer, perhaps even tube-based to make a hybrid.

Nice one, Mike.
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