Tremolo circuit in Harmony Vibrajet guitar

[alange5]

I'm restoring an old Harmony Vibrajet, which originally came with a tremolo circuit mounted in the body. The original parts are long-gone.  If possible, I'd like to replicate the original circuit.  I've attached a drawing of the schematic (found online), and a link to view the original patent, which contains a schematic (without values) and a description of the circuit:

https://www.google.com/patents/US3240859?dq=Electronic+tremolo+unit&hl=en&sa=X&ved=0ahUKEwi0hejYq7LVAhXD34MKHY1JANwQ6AEIJjAA

I'm looking for the specs of the small transformer sitting between the collector and negative voltage.  From on what I've read, it's acting as a frequency-specific blocking inductor.  A description from the patent:

"A blocking inductor or choke 33 is connected between the transistor collector 24 and the negative side of the battery 31 to block the tremolo signal from introduction into the battery."

Based on the schematic and patent description, any idea what value coil I should use?  Or perhaps an alternative?

Thanks

[PRR]

I do not recognize the oscillator circuit unless the choke is part of an L-C tank (which is not what the patent says).

Note that the patent and the 2013 trace are not the same circuit.

In simulation: the choke has to be both large and high-Q. I'm looking at 10H and 200 Ohms, which is not a practical part. The nearest available part would be a small tube output transformer, more like 10K than 2K nominal impedance. Even then it does not seem to oscillate eagerly, and does not shift frequency much.

Good luck!

[alange5]

I do not recognize the oscillator circuit unless the choke is part of an L-C tank (which is not what the patent says).

Note that the patent and the 2013 trace are not the same circuit.

In simulation: the choke has to be both large and high-Q. I'm looking at 10H and 200 Ohms, which is not a practical part. The nearest available part would be a small tube output transformer, more like 10K than 2K nominal impedance. Even then it does not seem to oscillate eagerly, and does not shift frequency much.

Good luck!

Interesting.  Thanks for the info!  Seems like keeping it original might be more trouble than it's worth.  I think I may just use a more tried-and-true circuit.