But you can buy the whole kit complete with the flash tubes everything you need besides the coil. It can adjust the frequency or you can simply put a push button on. Never the less it flashes 4 times per second ( like the blood purifier from Dr. Beck. ) I buy my kits in South Africa for R 180 ( which is probably 25 US Dollars )
The only thing I change ( but its not necessary ) is the capacitor. The bigger the capacitor the longer it takes to charge but the stronger the magnetic field.