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 was found in a 1974 publication. It provides a tone indication of the temperature sensed by...
This is a simple rheostat circuit for motor control that works with voltages from 6 to 12 V. The...
This circuit with TTL compatible output was found in a 1968 US documentation. The circuit is...