Tremolo Design Question

[makinrose]

Good day Makinrose

All good information! I suppose if one wants a "vactrol" with data available and that actually conforms to the data sheet, the only option is Silonex, at least as far as current production goes? If you make your own you have the option to use a real light bulb with a filament

Some of the alternative interfaces get a bit complex or expensive. The p-ch jfet option is running out of jfets to choose from, at least those with leads. I imagine one could use a more common n-ch jfet if there were an interface between the tube oscillator and the jfet gate, but this would also require a small negative voltage supply. The latter is easy enough to do using any of the less-than-ideal bias circuits since this is a noncritical application.

If the circuit point is elevated by a small positive DC voltage and capacitively coupled in and out, then an n-ch  jfet could be used without the hassle of a negative rail. Voltage is "relative", so this is just like a cathode-biased tube where the cathode is more positive than the grid and the grid is therefore negative with respect to the cathode. Here, the jfet source is more positive than the gate, so the gate looks negative to the cathode. One could DC or AC couple the tremolo signal into the gate. I believe Mr. O'Connor showed something like this in TUT4.

Other options involve rather a lot of sand being added to the valve circuit.

Cheerio

So far only the Silonex ones seem to have the right specs.  I'm getting some parts in for DIY LDRs so hopefully I'll have an easy replacement if someone else wants to try this circuit. I'm sure a JFet is good idea but they are gettingn hard to source and the one from China are kind of iffy.  With this circuit  I like it because it sounds good, uses one triode, and has no ticking issues.   I've also seen a Mosfet driven version of it....