This simple very low power circuit can be used in a battery powered infrared tone trigger. We found it in an American documentation from the 90s.
This circuit was found in a Philips documentation from 1966. Its purpose is to drive the solenoid...
This TTL oscillator uses an old TV crystal, having been found in an American publication in 1976....
This is a high efficiency version with the MC723 which is the Motorola version for this well-known...