This circuit was originally suggested by General Electric in 1966 documentation to power decorative high voltage neon lamps. The transformer is 7,500 V for a current of 4 mA.
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....