Hello peeps!
I hope this is in the right place!
I've finally managed to make time to improve my little radio set that I built last year so that it could be entered in the schools science competition, but I'm struggling with the audio amplifier section, so that it can be used with a loudspeaker for more comfortable listening than at present, as it's only able to drive an earphone.
I want to keep things as simple as possible, but use only discreet components, (using chips or not being able to explain the circuit function will get marked down) and as the set is running on a single AA cell at the moment, keeping to that would be a nice feature too, but not absolutely necessary as we've been allowed to design for 3V. We've been allowed to use 3 transistors in the design, and in my case that means 2 can be used for audio. We can use BC 549, BC 559, BC327, or BC 337, or any combination. I've already used a BC 549 as the detector.
I know the power output would be low, but a few tens of mW from a 100mV input would be fine, and as the radio is medium wave AM, no pretence of Hi Fi is necessary.
Greg, our teach, says that I should look at a simple sliding bias design for battery economy, he said they are sometimes called "Gray amplifiers", but I've not found much suitable from searching the net, only big power amplifiers, and don't really know what they are, or how the principal works.
The audio at the moment is developed across the 300 ohm DC resistance earphones, and is 100mV on a strong signal.
I don't want anyone to do my work for me

but a push in the right direction would be sweet.
Luv. Ami.