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.
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.
like Dr. Frankenstein, it’s about time to bring this little fellow to life… or at least try. the schematic i have is a random luck of the draw internet find, and i have no idea whether or not it will work. however, testing will occur on the work bench soon enough to determine what needs to make this single-ended 5watter amplify.
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 (mAh) |
Typical Drain (mA) |
| D | 12000 | 200 |
| C | 6000 | 100 |
| AA | 2000 | 50 |
| AAA | 1000 | 10 |
| N | 650 | 10 |
| 9 Volt | 500 | 15 |
| 6 Volt Lantern |
11000 | 300 |