Fuzz Face - Q2 emitter DC voltage - why is it so stable?

Started by Lino22, November 16, 2022, 01:48:39 AM

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Lino22

Guys, i am sorry if i am asking something that has been answered many times but - why is the Q2 emitter DC voltage so stable and practically independent on the RE2 or RC2 size? I understand it is what biases the Q1 base with a steady DC value.
When the core started to glow and people started yelling, he promptly ran out the door and up a nearby hill.

PRR

Q1 emitter is normally grounded? Or a so-low value resistor that the DC voltage at Q1 E is tiny?

And let us ignore Q1 base resistor (assume very small) because that's usually the big drift.

Then Q2 E "must" rise to turn Q1 Vbe "just on". Large change of RC1 make small change of VbeQ1. RC2 has about no effect on the front end unless it is so large it starves the system.
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antonis

This might be enlighten..
(or further confusing..) :icon_redface:



P.S.
Semi-verified due to partial lack of coffee..
"I'm getting older while being taught all the time" Solon the Athenian..
"I don't mind  being taught all the time but I do mind a lot getting old" Antonis the Thessalonian..

Lino22

Thank you Antonis for taking time to help me, this really helped me to understand the interaction.
Thank you Paul.
When the core started to glow and people started yelling, he promptly ran out the door and up a nearby hill.