I can't seem to grasp how to calculate the values for a common emitter with a load resistance, to cascade an amplifier in multiple stages.

I'm trying to obtain an 8.5-9Vptp output from a 12V supply on a 5520 ohm load resistance. Not trying to achieve much gain since it can be achieved in earlier stages so ~5. I took:

Ic = 10mA

DC emitter 0.5V about ground

Vce min = 1V

This is what I've got

enter image description here

However, once I actually built the circuit on a breadboard the output ended up being 4Vptp, half of what I actually had in the simulation. What am I doing wrong?

Complete circuit: enter image description here

  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. Any conclusions reached should be edited back into the question and/or any answer(s). \$\endgroup\$
    – Dave Tweed
    May 9, 2019 at 11:18

1 Answer 1


For temperature stability, and the wide output Volts PeakPeak, I'd consider this


simulate this circuit – Schematic created using CircuitLab

  • \$\begingroup\$ Maybe add some description for why D1 and why R3 would need to be resized ? \$\endgroup\$
    – efox29
    May 8, 2019 at 20:34
  • \$\begingroup\$ 100 ohms for R2 and R3 are awful low resistance. why would you want so much current flowing down that branch and also have your input impedance so low? \$\endgroup\$ May 8, 2019 at 20:55
  • \$\begingroup\$ his resistor values are different, between the 2 versions of the 5X amplifier; thus the OP can replace the 100 ohms with what he finds will perform correct biasing and gain-setting. \$\endgroup\$ May 8, 2019 at 21:16

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