Found in a Motorola documentation from the 70s, this circuit makes use of transistors of the time. Modern equivalents can be used. The diode also supports an equivalent.
Found in a 90s Popular Electronics, this circuit excites a 40 kHz ultrasonic transducer. The...
Found in Popular Electronics, this configuration can be powered by voltages from 6 to 12 V....
This circuit can be powered from 4 to 12 V sources. Pin 6 is the positive supply. See more about...