Practice code oscillator (CB21696E)

In the figure we have an astable multivibrator driving a speaker to produce audio signals for Morse code practice.

Alarm and Immobilizer (CB24467E)
This circuit was found in the December 1976 issue of Radio Electronics magazine. The circuit...
EMG Monitor (CB13793E)
This electromyography monitor is from a 1978 publication on operational amplifiers. The components are...
Comparator Adjustable Shield (CB4589E)
An interesting interface solution that can be provided in some cases is the one shown in the...