This circuit for the 40 MHz band was published in Radio Electronics magazine in December 1957. Its purpose was to monitor the signals of the Russian satellite launched at the time.
This simple experimental circuit using only transistor produces a tone given by C1 and C2. Tone is...
This power supply may have 5, 6, 9 or 12 V outputs depending on the 78XX and 79XX series...
This circuit is from Philips' 60s documentation. The circuit can be applied to modern operational...