American Power Design: Designer of high voltage DC/DC converters. Product offering is from 0.5 Watts to 200 Watts and up to 8000 VDC. Full custom products available.
Electrostore: Our store has a large selection of electronic surplus parts specializing in high-voltage components and equipment, high power semiconductors, variable power supplies, test equipment, and other scientific/laboratory components.
High Power Electronic Systems: Southwest Research Institute offers engineering of pulsed power and high power electromagnetics: RF design, RF test, RF prototype, RF outsource, RF design, pulsed power
High Voltage Generating Circuits: Sam Goldwasser flyback transformer circuit is available here.
Interworld Electronics and Computer Industries Inc.: The company sells a range of high voltage non-inductive resistors and current shunts. Also, sells construction cost estimating software and digitizer tablets.
Mike's Electric Stuff: Vintage electronics, valves/tubes, lamps, geissler tubes, historic display devices, High voltage, tesla coils & misc. other science stuff.
Physicsci: Electronic schematics, high voltage, EM weapons, How to's, lifters, plasma, electromagnetics.
Power Inverters: Construction plans and detailed description for low cost power inverters for high voltage to power up radio amateur's electron tube transmitters.
Power Inverters: Power inverters, transformers, adapters and related equipment.
Sam's Laser FAQ: HeNe Laser Power Supply Design
Water Resistors: For High Voltage. Made with copper sulfate.
Winding Your Own Induction Coil: Make a simple HV induction coil. With a TV flyback and other cheap parts.