Variable oscillator for code practice (CB7317E)

This circuit is from Popular Electronics from the 90s. The integrated circuit is not very common nowadays.

Peak Signal Indicator (CB25966E)
This LED indicator circuit uses an LM339 comparator. The circuit was found in the January 1995...
Wireless microphone (CB9457E)
This version is one of many that can be found on our website. We found it in Radio Electronics from the...
AD Converter for Current Monitor (CB5246E)
Found in a 2005 Linear Technology application manual, this circuit provides outputs from a current...