Tube synth diy

Looking at some divide by two circuits:

I haven't had much luck prototyping the Pentode van der Pol type circuit nor the single tube pentode trigger circuits - yet. I think the key may be to use a negative supply to bias the suppressor (which I haven't done yet, and isn't always theoretically necessary). 

Anyhow I'll scan in some examples. Anybody gotten a good trigger or relaxation oscillator with the van der Pol model? It looks like this was the method of creating sub-octaves on the Hammond Novachord. 

Regards, 

Lorin E. Parker