In simple Circlotron schematic ( Ecc99 & 2x EL34 ) you can determine needed voltage swing by varying driver anode resistors , by varying LTP 100k trimpot you can adjust input voltage treshold before clipping .
LTP will achieve allmost 100% of driver stage AC balance which is important for Circlotron correct performance , this old style bootstapped driver stage is here allways integral part of output Circlotron power stage , without anode bootstrap driver stage well need around 600-700 VDC supply to drive correct Circlotron power stage , since Circlotron is basically formed from two CF .
1,6K is here actually Rk-Rk impedance not Ra-a` , 1/4 of impedance of convetional OPT Ra-a` .
Best Regards !
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you are not very optimistic 
well, whatever, a 40watt might clip at 15watt too
but if it clips at 15watt, I would consider that very good, actually
will it matter which tap I use for speaker out
I have 12-8-6-0 / 0-6-8-12 ohm
btw, primaries are 0-800/0-800 ohm, 1.6ohm P-P
and its air gapped C-core
a bit much for this, but whatever, Im happy if it works at all
much thanks to Banat
cheers
well, whatever, a 40watt might clip at 15watt too
but if it clips at 15watt, I would consider that very good, actually
will it matter which tap I use for speaker out
I have 12-8-6-0 / 0-6-8-12 ohm
btw, primaries are 0-800/0-800 ohm, 1.6ohm P-P
and its air gapped C-core
a bit much for this, but whatever, Im happy if it works at all
much thanks to Banat
cheers
I kept back for most of this.
But I just can't let this go:
Especially with a Circlotron style circuit,
where voltage references to ground may be ambiguous,
you absolutely must avoid an auto-transformer.
This is a death-trap,
just waiting for some child to tug a speaker-cable.
D.C. voltages stored in powersupply are just looking to empty themselves through some unforeseen or accidental connection.
The windings in the autotransformer will simply conduct DC.
Hydro would ban this, as would UL .
This will neither be legal nor moral.
Your second circuit is not much better.
This one also breaks the cardinal rule,
of keeping HV idle currents out of the secondary to speaker outs.
With a standard transformer you have 1kV of insulation/
protection from HV leaking to speaker lines.
This circuit defeats all the careful safety features of well-designed output circuits.
Please find a way to make it safe.
The original Circlotron had 2 kV transformer isolation from HV, in case of cap failure.
Look again - Think again:
But I just can't let this go:
Especially with a Circlotron style circuit,
where voltage references to ground may be ambiguous,
you absolutely must avoid an auto-transformer.
This is a death-trap,
just waiting for some child to tug a speaker-cable.
An externally hosted image should be here but it was not working when we last tested it.
D.C. voltages stored in powersupply are just looking to empty themselves through some unforeseen or accidental connection.
The windings in the autotransformer will simply conduct DC.
Hydro would ban this, as would UL .
This will neither be legal nor moral.
Your second circuit is not much better.
This one also breaks the cardinal rule,
of keeping HV idle currents out of the secondary to speaker outs.
With a standard transformer you have 1kV of insulation/
protection from HV leaking to speaker lines.
This circuit defeats all the careful safety features of well-designed output circuits.
Please find a way to make it safe.
The original Circlotron had 2 kV transformer isolation from HV, in case of cap failure.
Look again - Think again:
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