What purpose are the transistors serving in this CRT oscilloscope circuit?
You have a differential amplifier that adds two inputs:


one input is the horizontal position
the other input is the saw-tooth sweep


Gain is perhaps near 50. Q18 has about 5mA flowing from +180, through R57, through Q18, through R54 to -10V DC. Q19 is similarly biased. VR7 sets horizontal gain.






simulate this circuit &ndash; Schematic created using CircuitLab