This type of design can produce a very high amperage current for a faction a second that can used to do some useful work if properly harnessed. The switching device could be a rotating spark gap as used by Nikola Tesla or some high speed electronic device, it is my belief that only glass tubes such as diodes or triode valves are really good at this and not transistors as they cannot handle the high voltage and high current produced in these devices without burning themselves out..
As used by Edwin Gray in his invention the charging circuit is basically a 12 volt battery being driven by vibrating relays to pulse the power through a step up transformer to raise voltage from 12 volt to approx 3000 volts this then, is rectified and used to charge a bank of capacitors.
This bank of capacitors is then discharged for a nano seconds period into special design tube which seems nothing than a copper rod a spark gap some carbon and a series of concentric rings around the spark gap and the resulting power collected on those rings is then fed to the earth via a air induction transformer or to the positive terminal of the charging batteries .
The power appearing at secondary of this air induction transformer is then used to power the motoring coils of the specially design motor.
High Voltage Induction Coil
Another method used in early X-ray machine and also Marconi in his first radio transmission across the Atlantic ocean was the induction coil basically a two coils wound on a metal rod a small number of primary windings in heavier gauge wire and large number of finer gauge winding ,basically a step up transformer using the primary magnetic field to operate a switch that controls the power to the primary winding.
This causes the magnetic field in the primary coil to build up and down which then causes by induction an alternating high voltage output in the secondary coil.(most likely a square...