Ground referenced input for common collector amplifier by thebugger

113

01:18:58

Amendment to the popular voltage amplifier posted by user: thebugger that used a common collector ( emitter follower ) as a voltage amplifier with a gain of over 1. As mentioned in the comments this circuit has amongst other flaws the undesirable quality of having a floating input. By utilising a transformer at the input it is possible to obtain a ground referenced input as is the normal practice. The other circuit flaws still remain. I would like to carry out some practical measurements on a circuit of this type, my suspicion is that this amplifier could potentially turn into an oscillator due to the absence of negative feedback.

published 9 years ago

gasboss775

9 years ago

I built this circuit today with the exception that I used 2 x 1 megohm resistors wired as a potential divider to provide dc bias for the base of the transistor. I used a 12 V supply. Using a bc549c transistor with hFE=557 & a 10K pot, I was able to get a gain of around X23 prior to severe distortion. The gain was dependant on the supply voltage increasing for > 12 V and falling for < 12 V. I may carry out further investigations just out of curiousity. I also added a 100n cap between the collector (+Ve) and ground to aid stability.

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