Need help sourcing theremin inductors.

Posted: 2/29/2020 12:53:29 AM
otaviomad

Joined: 2/29/2020

So I'm making a theremin for myself and encountered the age-old problem of obsolete parts. None of the 5 inductors listed are actually available.
These are:

10 mH, 3-section, RIF choke(J. W. Miller #6306)

100 pH, hi-Q, variable inductor(Toko RWRS-T1015Z)

2.5 mH, 3-section, RIF choke(J. W. M i ller #6302)

5 mH, 3-section, RF choke(J. W. Miller #6304)

68 μH, hi-Q, variable inductor(Toko 154ANS-T1019Z)


Now, I know I won't be finding these anywhere, so I have to replace them. The question is: how? Each of these inductors has a different job. What specs matter and which don't? I suspect that the hi-Q ones need, well, a high Q. But what about the 3-section RIF chokes? Does the resonant frequency matter? The Q? How much can the inductance vary? Sorry for asking so many questions but I have barely started and I already found a roadblock. Thanks!

Posted: 2/29/2020 1:22:20 AM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014


Building a theremin is a facinationing journey.

Always get a a sound sample of any model you have interest.

This is the sound wav of my design, the finest Classic Theremin approach today.

All parts from Mouser for under $100

Christopher  
www.Hwy79.com

Posted: 2/29/2020 1:49:18 AM
otaviomad

Joined: 2/29/2020

wow, that's amazing! are the "in progress" pcbs functional? also, is your mouser shopping list up-to-date?
also - can I get the PCBDoc for that schematic? thanks!

Posted: 2/29/2020 2:00:21 AM
oldtemecula

From: 60 Miles North of San Diego, CA

Joined: 10/1/2014


I have one last test to do and that has made me lazy. PCB's will be ordered in the next two weeks. Mouser list will have fixed ferrite coils added with a variable capacitor. I learned this approach from the Thierrymin build while experimenting. Currently I use the IF Transformer cans. This has been a twenty year journey for me after buying a few parts from Radio Shack. I will update the  Mouser list in the next day or so.

Find a way to email me a mailing address and the circuit boards will be sent at no cost. The interesting thing about my PCB is either board can be a Volume Control or wonderful Pitch Board. Just flip a switch or two. The two boards are identical.

Christopher

Posted: 2/29/2020 2:09:29 AM
otaviomad

Joined: 2/29/2020

Here is the thing: I live in Brazil. I'll PM you my e-mail so we can talk in more details however I'm very interested in what you have, as it would help a lot in my journey.

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