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 uses a symmetrical power supply, and the motor is for the voltage indicated in the...
We found this circuit in an old documentation, but it is still current. General purpose...
The circuit exemplified in figure 8 is suggested by National Semiconductor and is based on an...