This receiver was found in a Japanese publication in 1967. The circuit uses germanium transistors and details of the coils are not given. Power is supplied by a 9 V battery.
This circuit activates a relay when raindrops fall on the sensor. The circuit is from 1960...
Instead of the lamps, LEDs can be used in series with 470 ohm resistors. The circuit is from an...
This circuit is quite simple to assemble, having been found in a traditional American publication. The...