This circuit is from Motorola documentation, but can be implemented with virtually any phototransistor and any general-purpose transistor. The supply voltage can also be changed.
The presented circuit generates signals in a 1:10 frequency range depending on the Ct capacitor. See the...
This useful circuit is used to test the insulation of cables, appliances, leaks in high voltage...
This circuit was obtained in an Electronic Design from the 80's. It has the adjustment of the gain...