Null Indicator (CB21930E)

This bridge was found in a Raytheon transistor manual from the 1960s. The transistors are germanium from the time.

Analog Multimeter (CB11829E)
This circuit from the 40's is a conventional analog multimeter with several scales. Its accuracy will...
Digital Inverter (CB17042E)
With this circuit, an external circuit can be controlled by turning it on or off and reversing it (if...
Continuity Test (CB5935E)
This circuit appears elsewhere on this site, but from different sources. Using the LM3900, we find this...