Makington

Audio Amplifier Project

This little amp is a project I built for an electronics class. The circuit itself pretty simple, just a few passive components and an LM386 amplifier IC. The base is an aluminum plate with some aluminum angle bolted on for the input and volume to be mounted in. It's got those felt chair-skootchy-things on the bottom as feet.

It's powered by a 9v battery and has a mono RCA input and a volume knob with built-in on/off switch.
I left room on the perfboard to convert the amplifier to stereo (essentially add another copy of the existing circuit for the other channel), should I want to.
Here's a close-up of the wiring/inner-workings. Not that the inner-workings are really all that inner, it being open and all... Anyway:
Shielded wire was used to connect the audio input to the amplifier to reduce radio interference. With a long wire connected to the input pin of the chip (instead of the audio jack), this circuit actually makes a decent radio. Ok, well, it's pretty bad, you can't even tune it, but you can definitely receive signals.

You can also see the improvised resonating chamber I made out of tissue-box cardboard. The bass response of the little speaker was, unsuprisingly, not that great, so I started experimenting with ways to improve it. I first took the speaker off the plate and mounted it in the end of a capped cardboard tube, which helped the bass a lot. This was, however, larger than practical, to I reattached the speaker to the plate and made a small box around it there instead. This helps the bass somewhat, so I'm leaving it for now, though I may yet make improvements.