I am Electronics Instructor at a Career Center for high school students. We use breadboards a good bit for labs and learn about DC power supplys and several different types of amps in the second year of my program.
In an attempt to build a large project that they can take with them at the end of the year, I have been working on a large breadboard amp that highlights all the different designs they see including everything from basic BJT CE amps all the way to LM3886 amps.
My problem is with a constant 120Hz hum that does not vary gain. I am currently using one common ground for power and signal (see attached image) and from my research, I think this is where my problem exists.
Over all the sound quality is good, with each section being actively filtered and driving components from my old car stereo which have been mounted in custom enclosures to fit my work bench.
Unfortunately I have yet to produce one large schematic showing the entire layout, but any help you can give me based upon my description and the attached images would be greatly appreciated.
In an attempt to build a large project that they can take with them at the end of the year, I have been working on a large breadboard amp that highlights all the different designs they see including everything from basic BJT CE amps all the way to LM3886 amps.
My problem is with a constant 120Hz hum that does not vary gain. I am currently using one common ground for power and signal (see attached image) and from my research, I think this is where my problem exists.
Over all the sound quality is good, with each section being actively filtered and driving components from my old car stereo which have been mounted in custom enclosures to fit my work bench.
Unfortunately I have yet to produce one large schematic showing the entire layout, but any help you can give me based upon my description and the attached images would be greatly appreciated.