I'm studying old equipment BJT amplification, and I often see this kind of biasing design I reproduced in circuitJS (and seems to work very well):
The AC generator on the left is a tape recorder play head (~3mV). I don't understand how the biasing works here; if you have any information/link about this circuit or know the name of this configuration.
It is called negative feedback biassing.
The 220k base bias resistor R1 (assuming you'll put obvious reference designators in later, to make it easier to discuss the circuit) is coming from Q1 collector via the emitter follower Q2. It's an emitter follower at DC, even though it's an amplifier at AC thanks to the 1600 uF capacitor.
Basically Q1 collector voltage adjusts itself so sufficient base current flows through R1. If Q1 collector voltage is too low, base bias current reduces, collector current drops, and collector voltage rises, is vice versa.
tape recorder might say that to me. But not everyone knows. Besides, who can read your mind??? Seriously. The only way one might guess that you were asking about input impedance is to literally read your mind. My crystal ball is definitely broken. Hasn't worked since I got it. You do need to talk about what's going on in your mind and be direct about your question. If you wanted the input impedance, then write it out! Simple. Don't make people guess. Don't mean to be hard on you about this. I'm mostly just joking with you. But there's an element of truth, too. ;)
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19-(Vc-2*.6)/220*200e3=Vc. This solves out as 1.22 V. But since I didn't take into account the drop across the 220k resistor, the slight error is forgivable. This isn't rocket science. \$\endgroup\$19-(Vc-2*.6-(Vc-2*.6)/220/200*220e3)/220*200e3=Vcand that solves out to 1.195 V!! Slightly closer. Why is this so hard? Just plug and play. ;) \$\endgroup\$