This circuit can be used as a lockable shield. A pulse activates the relay that remains on even after the pulse disappears. The transistor is general purpose.
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...