[sdiy] Fet to short pedal input?

[brianw]

On Nov 28, 2025, at 2:09 AM, Roman Sowa <modular at go2.pl> wrote:
> This is so far from the truth I can't believe you say that.
> Saturated BJT works both ways. In any case it does not work like a diode. In saturation the base voltage is higher than other 2 terminals (assuming NPN) so both junctions are open, enabling free flow of current in both directions

I am aware that saturation mode exists, but I don't really understand how to design with that mode. At the very least, I never see it in circuits outside power supply regulation or power amplification. In particular, I've never seen a saturated BJT used like an electronic bypass switch, which seems like what is needed here.


> BTW, BJTs are most commonly used everywhere for muting output jacks during powerup or whatever other reasons, because it works so much better than FET in this application

I've only ever seen FET used for muting. In particular, I've seen depletion mode N-FET used because they conduct (to ground, in a mute circuit) when no voltage is applied to the gate. How would a BJT remain in saturation mode when all power is lost to the device?

> Roman
> 
> W dniu 2025-11-28 o 02:06, brianw pisze:
>> A BJT will conduct current in only one direction. In that sense, it's not like a plain, shorted electrical contact, but instead more like a diode. Also, the Emitter of a BJT is probably connected to ground, and the Base would only turn on the BJT if it's sufficiently higher in voltage than the Emitter. If you just let the Emitter float, the BJT won't work reliably.
>