Fig. 1.10. Induction coil with hammer break. Electric current from the battery (E) is fed to the primary circuit of the induction coil (A). This current pulls the hammer with the magnetic field of the solenoid (close to G) and breaks the circuit with the contactor (D). Through the vibration of the hammer this breaking is continuous and it induces a high voltage alternating current in the secondary circuit in (A). This current is applied to the patient with electrodes (H)..