This circuit from an old documentation includes the power supply for the 117 V power grid. It can be adapted to other networks by changing the 10k resistors.
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....