Found in the May 1971 Radio Electronics magazine, this is the circuit for a commercial high-impedance instrument. The circuit uses 4 transistors and is powered by 2 9 V batteries.
This two-color LED indicator was found in a Popular Electronics from the 90's. The transistor...
This circuit was found in a Radio Electronics from the 90's. It provides lower frequency signals from...
This monostable circuit uses one of the two flip-flops available on the CMOS 4098 integrated...