[sdiy] anti pop mosfets in minibrute

[Adam (synthDIY)]

I thought you were just inspired to test the clipper FETs in your phone...

> On 25 Apr 2024, at 10:23 am, Shalom D Ruben via Synth-diy <synth-diy at synth-diy.org> wrote:
> 
> That’s embarrassing… first post and it’s an accident. Sorry!
> 
> ___________________________________________Please excuse the brevity and tpyos as it was sent from my smartphone. 
> From: Shalom D Ruben <shalom at colorado.edu>
> Sent: Wednesday, April 24, 2024 6:22:36 PM
> To: Chris McDowell <declareupdate at gmail.com>; Mike Bryant <mbryant at futurehorizons.com>
> Cc: SDIY List <synth-diy at synth-diy.org>
> Subject: Re: [sdiy] anti pop mosfets in minibrute
>  
> Can we talk over the phone?
> 
> Thanks,
> Shalom 
> 
> ___________________________________________Please excuse the brevity and tpyos as it was sent from my smartphone. 
> From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Chris McDowell via Synth-diy <synth-diy at synth-diy.org>
> Sent: Wednesday, April 24, 2024 5:59:14 PM
> To: Mike Bryant <mbryant at futurehorizons.com>
> Cc: SDIY List <synth-diy at synth-diy.org>
> Subject: Re: [sdiy] anti pop mosfets in minibrute
>  
> [External email - use caution]
> 
> good point Mike. And even at 600, the clipping would be barely noticeable at full volume, thus sayeth the spice man 
> 
> Cheers,
> Chris 
> 
>> On Apr 24, 2024, at 6:48 PM, Mike Bryant <mbryant at futurehorizons.com> wrote:
>> 
>> 
>> I think the designer assumed the use of consumer 32 Ohm headphones rather than the pro 600 Ohm ones. 
>> From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of Tom Wiltshire <tom at electricdruid.net>
>> Sent: 24 April 2024 23:24
>> To: Chris McDowell <declareupdate at gmail.com>
>> Cc: SDIY List <synth-diy at synth-diy.org>
>> Subject: Re: [sdiy] anti pop mosfets in minibrute
>>  
>> 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 <mailto: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
>>> 
>>> 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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>> 
> 
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