BJT triggering below Vbe

231

02:43:15

On the left is a NPN circuit that triggers when the input signal drops below 84mV (much smaller than the 0.7 drop of the transistor).  And on the right is the PNP version that triggers when the signal is closer than 80mV to the positive supply voltage.

published 3 years ago

592azy2circuitdude

3 years ago

Clever circuit 👍 I noticed that the input trigger signal is applied to the emitters of the transistors. I've never seen that configuration before. What's it called?

Issacsutt

3 years ago

Thanks! Technically it’s a Common Base Configuration, but to be truly utilized it probably needs a buffer or one additional amplifier stage cause there’s no current gain

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