The circuit shown is from National Semiconductor's Linear Applications Handbook. It makes use of the LM78S40 which is not an easy component to obtain today.
This is one of many possible circuits for the LM3914 IC as an audio indicator. The trim pot has...
This elementary receiver with a crystal earphone was found in Japanese documentation from the...
This circuit was suggested by National Semiconductor in one of its manuals. The LM108 integrated...