High Frequency VFO (CB21141E)

Found in Popular Electronics from the 1990s, this variable frequency circuit generates signals in the shortwave range. FETs admit equivalents.

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DC to DC Converter (CB6580E)
This circuit was found in an American documentation from 1970. We can increase the number of...
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The presented circuit allows to control the valve of a tap. The positioning of the emitter and the...
Operational Amplifier Test (CB11246E)
I found this circuit in an old British magazine from 1976. It is possible to test operational...