Low Battery Detector (CB6515E)

This circuit was found in an 80's EDN. The circuit uses a current common CMOS, the 4093 powering an LED. Trigger adjustment is done in a trimpot.

| Clique na imagem para ampliar |

Fast photoelectric relay (CB23760E)
This fast trigger circuit allows the counting of up to 300 pulses per minute. The circuit is from...
Old Intercom (CB18542E)
This intercom uses transistors from the 60s. It was found in a Japanese publication at the time....
Flasher for Mobilete (CB18809E)
This circuit is from an old publication from the 90s, but it can be adapted to operate with LEDs....