A gain stage example to help with biasing transistors

[Gus]

Here is a gain stage sim screenshot
Two different transistors often used in effects and different supply voltages
The resistor values used are standard fixed values and were selected for a stable bias with changing supply voltage
As often with a circuit like this the parts selection is a compromise.  The input resistance is on the low side, just looking at it you should see it is under 47K
with C1 and R6 removed the gain is under 5
Does the schematic help?
discuss

[LucifersTrip]

I always like to see the hfe to collector voltage chart,  so I have an idea where increasing/decreasing hfe makes very little change to the collector voltage.
(ie, what's the sim with hfe 50 and hfe 800)

[Gus]

Some more biasing examples

[Gus]

I am bumping this because I think it is helpful

Note  the Q2 collector voltages
How they change with supply voltage
How they change with different beta Hfe
compare to the other bias methods

[Gus]

a bump because I saw some bias questions and another sim screenshot

[jafo]

Could you expound a bit on how R7 does its thing? Is it limiting current to B? Adding input impedance?

[antonis]

Could you expound a bit on how R7 does its thing? Is it limiting current to B? Adding input impedance?

It just puts itself in denominator place of NFB gain formula..