LM386 Square-wave Oscillator

Here’s a small LM386-based square-wave oscillator built from the following schematic. I replaced the 30k resistor with a 50k Potentiometer from my stash of parts which then, of course, acts as a pitch controller. The following audio is some track recordings made in Ableton 8.0 with a little filter on one track and some reverb the air-raid siren sounding noise.

No. 5 speaks.

and what a lovely voice it is. even through a Crate speaker (i’m saving the better speakers for when the testing phase is over). overall, i’d say a success for cheap transformers, Radio Shack parts, and a few pieces taken from a busted computer power supply.

audio notes: it was late, and i was annoying enough playing at midnight. the mic is sitting just above the speaker which was laying face up in a milk crate. i’m currently using a 100k audio pot, and i think it would fair better with a 1M. overall though, the amp is surprisingly quiet at mid volume. i still need to drill out the hole for AC connector, but it will come in due time. for now, it’s making sound and that’s a huge first step for me.

Typical Alkaline Battery Ratings

Also posted on the 8088 Networks site. I was using this to create a small external power supply for my Yeasu VX-3R. I used a 9v battery initially and realized that I should use a voltage drop to improve the battery life. Without any sort of voltage drop, the battery was dead in a little over an hour due to the fact that a full 500mA was flowing into the radio.

Battery Type Capacity
Typical Drain
D 12000 200
C 6000 100
AA 2000 50
AAA 1000 10
N 650 10
9 Volt 500 15
6 Volt
11000 300