This circuit with the PLL4046 was found in the October 1994 Electronics Now magazine. The transistor is low power, and the volume obtained is small.
This circuit was found in a Electronics Handbook (1989). The shown amplifier provides a few...
This circuit was found in the October 1993 Electronics Now magazine. The output transistors form...
Several types of OSEPP sensor modules can be obtained from Mouser Electronics for Arduino...