Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Tonight's efforts reminded me of this


Anyhow I got to thinking why dont you just try to build an amp based on stuff you have done so far  :tu:

So I set everything up and here is the schematic

IMG_20260224_220427123 (1).jpg

With everything assembled it looked good I had a nice Vbe like 0.61

So I had a scope probe channel one on the input (base) and a scope probe channel two on the output (collector)
and never could get an amplified signal.  :'(

Finally I noticed that whenever I increased input signal Vb dropped and would continue negative as input signal was increased  :grr

And I think I know the answer to this is that the signal generator is acting as ground to DC voltage  xP
But I have a capacitor there which should prevent that  :grr
Maybe it's the other way around.  Like when the signal voltage is negative it's traveling across the base resistor.

I need to figure out a way to get signal to the base without disturbing the bias.
Yeah I know modern man figured this out sixty or seventy years ago.   :lmao:

Ok I was sitting here listening 🎧 to Benjamin (RIP 🙏) pondering this and it occurred to me maybe raise Vb to keep it positive.  Which I'm not sure how to do I'll have to think about it  :lmao:

Keep Vb > input signal  xP

Seems like I could lower the value of the base resistor  :loco

Back at it  :loco did a few calculations  :tu:

IMG_20260225_091036517 (1).jpg

IMG_20260225_090953048.jpg

 :dbtu:

Input signal about one volt peak to peak

Output about 8.6 volts peak to peak

Now what bothers me is if I'm measuring output at the collector why are the two signals somewhat in phase  :grr

Also I connected the output to two different speakers and no sound.
I did accidentally notice that connecting a speaker 🔊 pulled down Vb  xP

How is the base referenced to ground?

Yes sir thanks
The signal gen lead red probe on neg terminal of capacitor then black probe on neutral/ground

I don't have an actual ground might be good practice to start having one  :'(

Without going into the theory of a Class A amplifier, my only suggestion would be to rethink the biasing of the transistor base.
You should have a resistor to ground.
Here is a simple schematic that I grabbed.