100 Hz Second Order High Pass Filter (CB25815E)

This filter with the 741 op amp was found in the February 1995 Electronics Now magazine. The power supply must be dual.

Capacitance meter (CB22163E)
Found in an English documentation from 1989, this circuit uses components common today. The...
Simple capacitor test (CB7060E)
The LED frequency flashes depends on the value of the capacitor tested according to the table. We...
Hartley crystal oscillator (CB7541E)
Found in a Popular Electronics from the 90s, this circuit generates a signal that depends on the...