SYclotron schematic

[SpreadSpectrum]

Lately I have been interested in the circlotron circuit. Anyway, some dude on the interwebs put this "SYclotron" circuit on his website. The problem is, only half of it is there. Anyone know where to find the other half?

[Cal Weldon]

Maybe ask SY if he knows anything.

[SY]

Hmmm, I'll get around to fixing that one of these days.

In the meantime, here's a link:

Fun little P-P input stage

I've revised the circuit a couple of times and ought to update. The circuit as posted served me well, but subbing LEDs for the cathode bias resistors was a worthwhile upgrade.

[SY]

Originally Posted by Cal Weldon

Maybe ask SY if he knows anything.

My wife will tell you that I don't.

[jrenkin]

Sy, it seems many different tubes could be used in this configuration with only a few adjustments. What are the features that led you to choose the 5691?

I am working on a PP amp that needs a gain of about 15-20 for the front end only and was going to use a long tail pair with a CCS tail using 12AT7 as the input and phase splitter. Gain around 30, so plenty. Are there advantages to your circuit over this? Maybe I will try both.

[StevenOH]

Here is old German Circlotron from '50-'60s. P out is ~20W.

[SY]

Originally Posted by jrenkin

Sy, it seems many different tubes could be used in this configuration with only a few adjustments. What are the features that led you to choose the 5691?

I am working on a PP amp that needs a gain of about 15-20 for the front end only and was going to use a long tail pair with a CCS tail using 12AT7 as the input and phase splitter. Gain around 30, so plenty. Are there advantages to your circuit over this? Maybe I will try both.

The 5691 had the right gain for the application (front end for various ST70/MkIII mods), excellent linearity, and low microphonics. Without the transformer, balance is better with higher mu.

I'm unconvinced that my circuit is better than a well-designed LTP in all respects except one; the one area where it is clearly better is input capacitance- it's MUCH lower and provides a better interface for the input transformer.

[jrenkin]

Originally Posted by SY

The 5691 had the right gain for the application (front end for various ST70/MkIII mods), excellent linearity, and low microphonics. Without the transformer, balance is better with higher mu.

I'm unconvinced that my circuit is better than a well-designed LTP in all respects except one; the one area where it is clearly better is input capacitance- it's MUCH lower and provides a better interface for the input transformer.

So without an input transformer, maybe it is a tossup?

[SY]

Without an input tranny, unless there was a really good reason to avoid input capacitance, a CCS-tailed LTP will have better balance than my circuit and would be my fist choice.

[tubesguy]

Originally Posted by SY

Without an input tranny, unless there was a really good reason to avoid input capacitance, a CCS-tailed LTP will have better balance than my circuit and would be my fist choice.

Them's fightin' words.