These valves make use of electromechanical solenoids for sliding of the spool. His tabulator used electromechanical solenoids to increment mechanical counters. Control for the solenoids and stepper motors can be either closed loop or open loop. Solenoids and Helmholtz coils are types of coils that can be used for this purpose. Modern electronic automatic transmissions have electrical solenoids which are activated to change gears. The exact wiring between switches and solenoids is still classified. There are also problems with the valve block and solenoids. The electronic systems, extra hoses, solenoids and soforth add complexity to the turbocharger system. The activators are solenoids of one millimeter diameter. In 1909, he published a paper on the inductance of solenoids. Many ingenious mechanisms were invented to affect the distance automatically, mostly based on solenoids. Persinger uses a modified snowmobile helmet that incorporates solenoids placed over the temporal lobes. Toshio possessed some knowledge of electronics and set out to make a calculator using solenoids. That limits the simple analysis to low-permeability cores, or extremely long thin solenoids. To accommodate the solenoids, the puppets' heads were made as hollow shells.