Using an LDR as a sensor, this circuit is from the Radio Electronics magazine of December 1984. The operational amplifier is the 741 and the source must be symmetrical.
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...