• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Video Amp Circuit Modification

Les Jones

Well-Known Member
By adding the capacitors you will have lost the DC component of the video signal. It may work with some video equipment if it's input circuit incudes DC restoration.


Nigel Goodwin

Super Moderator
Most Helpful Member
Also the capacitors are really too small - and probably not needed anyway, the input it's feeding 'should' have DC blocking, but AFTER the 75 ohm load resistor, this allows much smaller capacitors.


Active Member

If I remove the output capacitors & by mistake if I short circuit the output to ground will it damage the transistor?


Active Member
No, there's a 75 ohm resistor which limits the current, and in normal use theres two 75 ohms (150 ohms) in series to ground anyway.
In my circuit when shorted 5V/75R=66mA current will flow through the transistor.....!!!

Do I need another 75 Resistor ?


Well-Known Member
Most Helpful Member
if you were to use 2N3904/3906 transistors here, the max Ic would be 200mA, so short circuits at the output wouldn't be a problem.

Latest threads

EE World Online Articles