Dolby noise reducer (CB21105E)

This circuit was found in a National Semiconductor Handbook from the 1990s. The integrated circuit used is from the time and the circuit is stereo.

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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...