Thanks! What I still don’t quite understand is where I would “apply” voltage in the inverter based circuit. I guess an inverter is a mosfet or two? And that comes with a power source, and so the output of the inverter starts at a (presumable low) voltage and then tries to invert it, and then it “gets going”.
Do they have a polarity? An optimal voltage range (maybe that comes down to the inverter/amp circuitry)? I recall their data sheets being a bit thin but it’s been a while since I looked.
Maybe I need to put some things on a breadboard to get going.
My question is kinda like: if I have a couple volts somewhere (probably more like 100mV AC for a short period), and I wanted to make some oscillations at a known frequency how would I go about it?
Yeah, basically. An inverter is powered externally, it's just sort of implied - same as with op-amps. It's a bunch of transistors that are notionally just supposed to output 0 V when the input signal is above a certain threshold and 5 V (or some other positive rail voltage) if the signal is below. But internally, it's just a crappy, high-gain inverting amplifier.
If you have AC voltage, then you already have oscillations, right? If you want another frequency, then I guess it's a bit tricky because most transistors need more than 100 mV to do something useful (well, you could probably work with JFETs?). But if you have AC supply, you can boost it with a voltage doubler (or a number thereof) until you get to some reasonable level...
My 100mV AC source is actually an electric guitar pickup. I was thinking I could leech a small amount of power into a little bank (but this I guess might be blocked by finding a diode that operates at 100mV...). I'm open to mechanical power sources too, like kinetic power the Philips Hue Tap switch uses, or like winding a watch (off that wammy bar, ha!).
Then I want to periodically add a 50+kHz signal on top of the audio output, to be decoded by a pedal or whatever downstream (but my goal was to do this passively, and have the tone knob on the guitar able to control some digital circuit on the receiving side by sending various values).
Of course, the marketplace of clock sources is a bit of a rabbit hole on its own.
In addition to standard xtals, there are temperature-compensated or temperature-controlled variants (TXCO and OCXO), the latter reaching parts-per-billion accuracy (but also costing a lot). Then, there are ceramic resonators, made from the same material as piezoelectric transducers; this is cheaper than quartz and less bad than RC circuits - good enough for applications such as USB or Ethernet. Finally, there are integrated modules that might contain an amplifier and a programmable divider / PLL.
Thanks! What I still don’t quite understand is where I would “apply” voltage in the inverter based circuit. I guess an inverter is a mosfet or two? And that comes with a power source, and so the output of the inverter starts at a (presumable low) voltage and then tries to invert it, and then it “gets going”.
Do they have a polarity? An optimal voltage range (maybe that comes down to the inverter/amp circuitry)? I recall their data sheets being a bit thin but it’s been a while since I looked.
Maybe I need to put some things on a breadboard to get going.
My question is kinda like: if I have a couple volts somewhere (probably more like 100mV AC for a short period), and I wanted to make some oscillations at a known frequency how would I go about it?
Yeah, basically. An inverter is powered externally, it's just sort of implied - same as with op-amps. It's a bunch of transistors that are notionally just supposed to output 0 V when the input signal is above a certain threshold and 5 V (or some other positive rail voltage) if the signal is below. But internally, it's just a crappy, high-gain inverting amplifier.
If you have AC voltage, then you already have oscillations, right? If you want another frequency, then I guess it's a bit tricky because most transistors need more than 100 mV to do something useful (well, you could probably work with JFETs?). But if you have AC supply, you can boost it with a voltage doubler (or a number thereof) until you get to some reasonable level...
My 100mV AC source is actually an electric guitar pickup. I was thinking I could leech a small amount of power into a little bank (but this I guess might be blocked by finding a diode that operates at 100mV...). I'm open to mechanical power sources too, like kinetic power the Philips Hue Tap switch uses, or like winding a watch (off that wammy bar, ha!).
Then I want to periodically add a 50+kHz signal on top of the audio output, to be decoded by a pedal or whatever downstream (but my goal was to do this passively, and have the tone knob on the guitar able to control some digital circuit on the receiving side by sending various values).
Of course, the marketplace of clock sources is a bit of a rabbit hole on its own.
In addition to standard xtals, there are temperature-compensated or temperature-controlled variants (TXCO and OCXO), the latter reaching parts-per-billion accuracy (but also costing a lot). Then, there are ceramic resonators, made from the same material as piezoelectric transducers; this is cheaper than quartz and less bad than RC circuits - good enough for applications such as USB or Ethernet. Finally, there are integrated modules that might contain an amplifier and a programmable divider / PLL.