Bearfoot - Mint Green Mini Vibe

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Bearfoot - Mint Green Mini Vibe

Postby Kinkajou » 31 Dec 2011, 15:41

Happy New Year!

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batteryacidtea (31 Dec 2011, 20:48), culturejam (05 Jan 2012, 15:36), joeboo88 (01 Jan 2012, 00:54), LaceSensor (02 Jan 2012, 02:46), lolbou (05 Jan 2012, 11:09), modman (08 May 2015, 14:37), Nocentelli (03 Jan 2012, 15:15), phibes (01 Jan 2012, 10:09)
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Re: Bearfoot - Mint Green Mini Vibe

Postby Kinkajou » 04 Jan 2012, 22:55

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

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modman (08 May 2015, 14:37)
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Re: Bearfoot - Mint Green Mini Vibe

Postby phibes » 05 Jan 2012, 02:38

Do you own the unit? This one looks like a bitch to trace with the majority of the traces being on top...
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Re: Bearfoot - Mint Green Mini Vibe

Postby Kinkajou » 05 Jan 2012, 09:03

no. only had chance to peak inside. I could not trace myself as everthing to tight. :(
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Re: Bearfoot - Mint Green Mini Vibe

Postby culturejam » 05 Jan 2012, 15:52

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?

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Re: Bearfoot - Mint Green Mini Vibe

Postby Flaconsius » 30 Jun 2018, 02:45

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