This circuit was found in a 1985 documentation. It provides an audiovisual indication of the presence of moisture or water in the sensor. The circuit can be powered by voltages from 6 to 9 V.
This circuit was found in a Motorola documentation from 1975. Modern equivalent transistors such...
This circuit is from the datasheet of STMicroelectronics, being indicated for the voltage...
This circuit was found in 1980's Radio Electronics. The circuit produces a 1500 Hz modulate 35 kHz....