We found this circuit in an old Popular Electronics. The circuit is experimental, driving an LED from signals applied to the LDRs. The power supply does not have to be symmetrical.
The 747 is an old operational amplifier. This configuration suggested in the component manual is...
Suggested by Siliconix in 1980s documentation, this circuit uses currently uncommon components. The...
In the figure we have a circuit to excite a piezoelectric capsule taking advantage of its resonant...