This circuit was found in an Australian publication from 1991. It is a transmitter that transmits a signal when it detects moisture. The range is on the order of a few tens of meters.
This circuit uses two transistors and can be powered by just two small batteries. The frequency is given...
This circuit was found in the February 1985 issue of Radio Electronics magazine. It is based on an...
This circuit from Ferranti was released in 1969. It makes use of the company's transistors that admit...