Of course, the current is extremely small, but a voltage of 300 V can be obtained from 9 V of a battery. The circuit is from an Electronics Now of May 1994. C1 adjusts the operating point.
If you have a common analog multimeter, you can increase its input resistance in the measurement of...
Found in a 1968 documentation, this small amplifier was very popular at the time being used in...
Found in a magazine 73 for radio amateurs, this circuit operates in the 144 MHz band, at a...