This sophisticated circuit with two LF411 operational amplifiers appeared in the November 1984 issue of Radio Electronics magazine. The circuit uses a Mallory buzzer as an indicator.
This circuit was found in a RCA documentation from 1977. The integrated circuit is uncommon today. It is...
We found this circuit in a 1995 documentation. It can measure frequencies from 100 kHz to over 100 MHz...
This circuit was obtained in a Popular Electronics of the 90s. The circuit is compatible with...