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.
Originally designed to analyze the shape of light pulses from a flash for photographic...
This RCA circuit has current limitation. The circuit is from an ancient American documentation making...
This useful power supply was found in an 1985 Italian publication, but can still be assembled...