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SO when I was a kid, transistors were a new thing. I'd read Popular Electronics and similar hobby electronics magazines. A common build-it article for a transistor was the "code practice oscillator." Ham radio was still a big deal then, and learning morse code was required. SO people were always coming up with dumb little circuits that went beep when the switch was closed. SO making noise was kind of a passtime.
I found various silly ways to do it. When you are a kid, you try things you might not when older. What possessed me, I'll never know, but one day I took a small electric motor, like from a toy and connected it to a battery to make it spin, then for some reason I wired a speaker in series with it. Just a cheap brush type motor, we didn't have brushless ones then. What a noise. Kinda like holding a power drill right next to your guitar pickup. Forbidden Planet being a cool film of the day, we imagined it sounded a little like the Krell monster.
My favorite thing was a relaxation oscillator. Imagine a B+ voltage. I think I was using 90v, but it doesn;t matter really. Put a resistor and neon lamp in series, with a cap across the lamp. MAke the resistor large, like 1 meg, and use a reasonably large cap. Do the math for the RC time constant. The cap charges up over a few seconds. The neon lamp in parallel with the cap won;t fire until the voltage across it reaches its firing voltage - 60v maybe? So the cap charges up until it gets to the neon lamp firing voltage. The lamp strikes, discharging the cap, and the cycle repeats. I had a bag of hundreds of 1 meg resistors at the time, so I left that constant and varied the cap. Large cap, slow oscillation. Vup, vup, vup. Smaller cap, faster, even into audio. You can watch the bulb blink, or at fster speeds it just glows. So clip a coupling cap on it and feed this signal to an amplifier. Hear the oscillation. I made more R/C/Neon circuits and paralleled them on the power source. It wasn't well regulated, so they interacted. The one would be a second or so, while the other would be a few hundrd Hz. The audio one would slowly ramp up in freq until the other one fired. SO the whole thing went up and down in a cycle like a police siren. Well, more like a sweep generator. One could also connect one RC to the junction of another. There were various ways to interconnect them. I managed to get a sound like a sweep generator of a set range while the base freq slowly rose then reset. A swept sweep, as it were. All with a 90v battery supply, a bunch of 1 meg resistors and a pile of miscellaneous caps.
And when I got into building amps, I was always connecting this to that to make them oscillate.
My sister really hated when I;d feed noises into the phone wiring while she yakked with her friends. And mom hated noise of any kind, telling down the stairs "Stop whatever it is you are doing... NOW."
I found various silly ways to do it. When you are a kid, you try things you might not when older. What possessed me, I'll never know, but one day I took a small electric motor, like from a toy and connected it to a battery to make it spin, then for some reason I wired a speaker in series with it. Just a cheap brush type motor, we didn't have brushless ones then. What a noise. Kinda like holding a power drill right next to your guitar pickup. Forbidden Planet being a cool film of the day, we imagined it sounded a little like the Krell monster.
My favorite thing was a relaxation oscillator. Imagine a B+ voltage. I think I was using 90v, but it doesn;t matter really. Put a resistor and neon lamp in series, with a cap across the lamp. MAke the resistor large, like 1 meg, and use a reasonably large cap. Do the math for the RC time constant. The cap charges up over a few seconds. The neon lamp in parallel with the cap won;t fire until the voltage across it reaches its firing voltage - 60v maybe? So the cap charges up until it gets to the neon lamp firing voltage. The lamp strikes, discharging the cap, and the cycle repeats. I had a bag of hundreds of 1 meg resistors at the time, so I left that constant and varied the cap. Large cap, slow oscillation. Vup, vup, vup. Smaller cap, faster, even into audio. You can watch the bulb blink, or at fster speeds it just glows. So clip a coupling cap on it and feed this signal to an amplifier. Hear the oscillation. I made more R/C/Neon circuits and paralleled them on the power source. It wasn't well regulated, so they interacted. The one would be a second or so, while the other would be a few hundrd Hz. The audio one would slowly ramp up in freq until the other one fired. SO the whole thing went up and down in a cycle like a police siren. Well, more like a sweep generator. One could also connect one RC to the junction of another. There were various ways to interconnect them. I managed to get a sound like a sweep generator of a set range while the base freq slowly rose then reset. A swept sweep, as it were. All with a 90v battery supply, a bunch of 1 meg resistors and a pile of miscellaneous caps.
And when I got into building amps, I was always connecting this to that to make them oscillate.
My sister really hated when I;d feed noises into the phone wiring while she yakked with her friends. And mom hated noise of any kind, telling down the stairs "Stop whatever it is you are doing... NOW."
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