At times we have a chance to perform evaluations where we can explore options. The audio amplifier stage was such an opportunity where I could explore integrating both NPN and PNP transistors in the same circuit module.
This is a 1st try where we used a 2N2222 NPN as the 1st stage. I will eventually convert the audio amp stage to all PNP transistors, but this looks promising.
Mind you the last couple of posts have been just simulations using LT Spice. I now need to build some hardware as proof of concept. But I thought sharing just the simulations at this point would get blog readers started on their own discovery journeys.
Math Check. For 34dB for 0.1 volt input the output is 6 Volts. Thus 20*log (6/0.1) ~ 35dB
The actual power is calculated as follows. The peak voltage is 6/2 = 3 Volts. Converting that to RMS = 3 * 0.707 = 2.121. Square that we get 2.121^2 = 4.498641. Now divide that by 8 = 0.56233 watts or 562 Milliwatts. Not too shabby and more output than a LM386! But we need the actual build to affirm the simulation.
In time I will convert this 1st try to make it all PNP devices.
Several of my homebrew rigs of the past have PNP circuits including the junk box transceiver with the Microphone amp and the (almost world famous) 40M MC1496 Direct Conversion Receiver which uses a PNP transistor in the RF Amp stage.
TYGNYBNT
73's
Pete N6QW