Published in a PE Hobbyst Handbook of 1991, this sensor uses an integrated circuit that is unusual today. The circuit is based on a high frequency oscillator.
This is the typical circuit of an FET amplifier stage in the common source configuration. The circuit is...
This voltage-controlled oscillator was found on an Elektor from the 90s. The components are from...
We found this circuit in an English publication from 1980. It provides a logical output signal when...