Found in Motorola's 1968 power circuit manual, this circuit has a high input voltage and no information was given about the transformers as the original types are commercial at the time.
This fast trigger circuit allows the counting of up to 300 pulses per minute. The circuit is from...
This intercom uses transistors from the 60s. It was found in a Japanese publication at the time....
This circuit is from an old publication from the 90s, but it can be adapted to operate with LEDs....