[sdiy] anti pop mosfets in minibrute

[Tom Wiltshire]

Isn't the problem when the output goes *over* the forward voltage of the diodes? Below that limit , they won't conduct, or barely, anyway. In which case, keep the voltage low, but drive the current (it's a low impedance headphone output) and no problem. When the mosfets are on, the output is shorted to ground. When they're not, you're ok up to that (roughly) 2Vpp limit.

Am I just catching up on what you've already worked out? Wouldn't be the first time...;)

Tom
 

> On 24 Apr 2024, at 21:14, Chris McDowell via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> <preview.png>
> MiniBrute-10-OUTPUT
> PDF Document · 339 KB
>  <https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>MiniBrute-10-OUTPUT <https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>
> PDF Document · 339 KB <https://hackabrute.yusynth.net/MINIBRUTE/digital-board/schematics/MiniBrute-10-OUTPUT.pdf>
> 
> hello list, I've been looking at minibrute schematics today and I'm puzzled by the anti pop circuitry in the headphone driver. it -seems- like the body diode of the mosfets would conduct when the signal went below 0.6ish volts (something I've run into this using mosfets for dc signal muting).
> 
>  From the vca page, that signal can be up to 2Vpp.  https://hackabrute.yusynth.net/MINIBRUTE/analog-board/schematics/MiniBrute-08-VCA.pdf <https://hackabrute.yusynth.net/MINIBRUTE/analog-board/schematics/MiniBrute-08-VCA.pdf>
> 
> What am I missing here? Is 2Vpp just fine in this case? Now reading the 2n7002 datasheet I see the forward voltage of the source-drain diode is typ 0.88V, 1.5V max. Did I just answer my own question? 😜
> 
> Cheers,
> Chris McDowell
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