Bearfoot - Mint Green Mini Vibe

Kinkajou · Post by **Kinkajou** » 31 Dec 2011, 14:41

Happy New Year!

Kinkajou · Post by **Kinkajou** » 04 Jan 2012, 21:55

As there are no LDR/LED combination in this, I guess it work by the principle to use JFET as a variabel resistor.
Similiar to following link, but using fets as buffers/amplifiers instead of opamps http://sound.westhost.com/project49.htm
TL061 and BC550 probably part of LFO.

interesting points
- use of voltage regulator (AS78L) regulating voltage to 5v. why?
- no trimmer (= jfets matched or is there other way to implement autotrimming?)
- 6 jfets, one more than circuit from link

other information http://www.vishay.com/docs/70598/70598.pdf

phibes · Post by **phibes** » 05 Jan 2012, 01:38

Do you own the unit? This one looks like a bitch to trace with the majority of the traces being on top...

Kinkajou · Post by **Kinkajou** » 05 Jan 2012, 08:03

no. only had chance to peak inside. I could not trace myself as everthing to tight.

culturejam · Post by **culturejam** » 05 Jan 2012, 14:52

Maybe it's similar to this:
http://classicamplification.net/forumvi ... h_vint.htm

So maybe two phase shift stages, but instead of LDR, it uses another JFET as the variable resistor? And the op amp + 550 is the LFO?

Flaconsius · Post by **Flaconsius** » 30 Jun 2018, 01:45

Just watching it without deails, its Active components look pretty similar to the EA Tremolo.