/diy/ - Do It Yourself

>>1199139
Depends on the voltage its meant to run on. if it's meant to go inside a speaker housing and take the already amplified audio signal, then probably not. I don't know what voltage amplified audio usually goes to, but you'll probably need to use an amplifier to get there. A single transistor amp like pic related should be fine.

If there is some sort of calibration potentiometer on the board then you might be able to get away with the amp being powered by the VU meter's PSU, or even just run it without an amp, so I'd mess around with the existing hardware a bit first. It might even have a built-in amp, though I wouldn't get your hopes up.

Hi /diy/ after lurking for a while I decided to build my first circuit. It's just going to be a common emitter to boost the output of my 5MHz radio before going into the power amp on the antenna. Nothing fancy, just for learning. After I did the calculations and built the circuit on a breadboard I found out it has a gain of just below 1, with the gain increasing up to 8 (what I designed for) when I attached a signal generator and dialed down the frequency (it increases linearly).

Is this a problem with the breadboard or is this not a good circuit for voltage amplifying a radio signal? I heard I was supposed to choose resistor values that create half the supply voltage over the CE Junction, but I don't know what this means so I chose Rc/Re = 8 with 12/(RC+RE) = 5mA which is half the rated collector current for forward biasing. Am I supposed to bias the base to something in particular? I set it so that the signal doesn't fall below 1v during its cycle as I heard transistors have a 0.7v loss from B to E so you have to have more than this amount at the base. Sorry if this is something simple, I am new to electronics and have no college courses in it.