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 circuit synthesizes a sinusoidal signal from logic pulses that can be obtained from an...
With the light falling on the LDR, the relay closes its contacts by activating a warning system. The...
This circuit was found in old English documentation. It can be improved by using resistors of...