How it works Oudin coil

in earlier oudin circuits 2 coils separate, not magnetically coupled, small horizontal primary d arsonval coil (l1) of 20-40 turns tap connected large vertical secondary oudin resonator (l2) many turns of fine wire (400 - 600 in large coils, 100 - 300 in small ones), connected high voltage terminal on top. in circuit high voltage generated entirely resonance in high q secondary coil. addition of resonator coil d arsonval coil oudin s contribution; rest of circuit invented jacques d arsonval.











in later oudin circuits coils magnetically coupled, forming autotransformer, primary induces emf in secondary electromagnetic induction. both coils wound on same coil form, primary consisting of relatively few turns of heavy wire @ bottom adjustable tap, connected secondary winding, made of many turns of fine wire. oudin found circuit produced higher voltages due large turns ratio of transformer.

although doesn t include capacitor, secondary winding resonant circuit (electrical resonator); parasitic capacitance between ends of secondary coil resonates large inductance of secondary @ particular resonant frequency. when excited @ frequency primary, large oscillating voltages induced in secondary. number of turns in primary winding, , resonant frequency of primary, adjusted tap on coil. when 2 tuned circuits adjusted resonate @ same frequency, large turns ratio of coil, aided high q of tuned circuits, steps primary voltage hundreds of thousands millions of volts @ secondary.

the secondary directly connected primary circuit, carries lethal low frequency 50/60 hz currents @ thousands of volts power transformer. since oudin coil medical device, secondary current applied directly person s body, safety oudin circuit has 2 capacitors (c), 1 in each leg of primary, isolate coil , output electrode supply transformer @ mains frequency. because 2 identical capacitors in series have half capacitance of single capacitor, resonant frequency of oudin circuit is

f
=


1

2
π



l

1


c

/

2








{\displaystyle f={1 \over 2\pi {\sqrt {l_{1}c/2}}}\;}