[sdiy] anti pop mosfets in minibrute

[brianw]

On Apr 24, 2024, at 8:01 PM, brian wrote:
> On Apr 24, 2024, at 7:31 PM, Chris McDowell wrote:
>> And yeah, you've got it right. Very brief mute, then disengage.
> 
> In that case, I wonder why they didn't use the depletion mode p-channel? Depending upon how fast the 5V supply rises at power-on, a capacitor might not even be needed for such a pop-mute circuit.
> 
> Maybe they got a bulk discount on n-channel enhancement mode FET parts, and saved enough money that the added capacitors to invert the logic were still cheaper.

Hmm, perhaps the answer is the failure mode. If all p-channel depletion mode FET fail by continuing to conduct, while the n-channel enhancement mode FET fail by staying high impedance, then the Mini Brute might just cease to mute pops, but would otherwise still have functional headphone outputs.

I actually assume that transistors have multiple failure modes, so perhaps you can't always rely on a graceful failure mode.

Brian