3-channel preamp (T484E)

This 4-tube circuit was found in an American publication from 1947. It is intended for audio distribution lines using a transformer source.

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Digital to Analog Converter (CB6673E)
This circuit using only transistors was obtained from Ferranti's 1969 documentation. It can be...
Modulated Light ReceiverIR4199S CB13885E (CB13885E)
This sensitive circuit can be designed with FETs such as BF245 and MPF102. The sensor is a silicon...
Dual tone generator (CB21080E)
Found in Popular Electronics from the 90s, this circuit generates two tones that are selected by a...