This circuit has the intensity of the signals controlled by the light that falls on the sensor. Note that it is not a frequency-controlled oscillator. Equivalent transistors can be used.
The TSC102 integrated circuit from ST-Microelectronics consists of a current sensor system that, in...
This circuit was found in old documentation, but the transistor may be the modern equivalent BC547....
The IC used in this project is not common these days, but if you have one you can build a high...