Found in American documentation from the 90's, this JFET stage has an input impedance of 500 M ohms. Bipolar transistors are general purpose types and the FET supports an equivalent.
This circuit was found in the June 1978 issue of Radio Electronics magazine. The circuit is...
The slope of an object causes the sensor, a mercury switch to be triggered. The circuit activates...
This circuit for the logic control of the 555 in a power supply was found in the October 1989...