112. Relaxation Oscillator Using a Comparator

This is a corrected video of a relaxation oscillator. Thanks to all the viewers that pointed out the incorrect placement of the capacitor. Feedback is always appreciated.

[@bobdoritique7347]

Merci for this video.

[@aerofart]

Can someone please explain how C1 can charge//discharge when one of its terminals is connected to the very high impedance of the op-amp inverting input input and the other terminal is tied to ground? It would have to be a very low value capacitor to exhibit any useful change in charge, would it not?

[@aerofart]

I think I spoke too soon. Looks like the second circuit (correctly drawn) explains how.

[@vlastimilelias]

But the second schematics has incorrectly connected R3. It must go to the ground to match the equations 1 and 2. Thanks to the author to keeping our brains working 😂

[@aerofart]

@@vlastimilelias I haven’t verified your claim independently, but in the absence of an argument to the contrary, I’ll take your word for it. Thanks for letting us know.

[@AnalogDude_]

How would you qualify the "timer/oscillator" circuit in the noise Circuit of the Roland TR-909 drum computer?
Using either Cd4030 or Cd4070.
What kind of math would apply there to calculate speed?