2-JFETs Oscillator (CB22396E)

This LC oscillator was found in English documentation from the 1990s. JFETs may be general-purpose equivalents.

Decibel Meter (CB24299E)
Found in the March 1974 Radio Electronics magazine, this circuit is designed to measure the level...
Adafruit Breakout PDM Microphone
Adafruit Breakout PDM Microphone This Adafruit tested microphone card is available from Mouser...
DC Millivoltmeter (CB8213E)
This circuit was obtained from a 90s Radio Electronics. The value of R1 determines the scale...