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.
This circuit was obtained from a Philips documentation from 1968. The transistors can be replaced...
The figure shows how to use the XR2206 to generate sinusoidal signals in a different way. The...
This headphone amplifier has good gain and high input impedance. The circuit is from Electronics Now and...