This 80's Exar circuit has a carrier detector for frequencies up to 500 kHz. The circuit uses a company 567 which is still a common component.
Using an LDR, this Philips circuit directly activates a relay when light strikes the sensor. The...
We found this light-effect circuit with LEDs using the well-known 4017 in a 1987 documentation. All...
This driver for audio signals using the TAA435 integrated circuit was found in Philips 1968...