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 shows how a monostable can be obtained from an RS flip-flop using a unijunction...
This circuit was found in an application note of the LTC1164 from Linear Technology of the 1990s....
Using a general-purpose transistor this AC amplifier was found in the November 1993 issue of...