This circuit is from a 1991 PE Hobbyst Handbook. The circuit uses two trigger transformers for a xenon lamp. The trigger element is a neon lamp that controls an SCR.
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....