This circuit has a correction or linearity adjustment. We found it in Ferranti's transistor manual from 1974. Transistors are general-purpose types at the time.
This logic probe was found in a Popular Electronics from the 90s. The circuit is TTL and must be...
The integrated circuit used in this configuration is not common today. The zener determines the...
The original frequency of the Pierce Oscillator with bipolar transistor is given by the crystal, which...