We found this circuit in a 1964 Electronic Design. It divides the frequency of a 20 MHz signal by 2. The circuit uses a transistor from that time. Details of the coils were not given.
Using a voltage comparator, we find this AND gate on a Popular Electronics from the 90s. The...
This crystal oscillator circuit is indicated for use as a frequency reference in the calibration...
Any operational amplifier can be used in this circuit. The 741 is the most common. Power supply must...