Carbon arc light project - First mechanism unit almost completed!

After many redesigns and countless prototypes of various mechanisms, I finally chose the H bridge as the core of the arc control device! The (almost) final version shown here uses four NO momentary switch.

The principle of this mechanism is to match the optimal arc voltage and current with a perfect equilibrium between a solenoid (which will be installed at left on the mechanism) and an adjustable spring (at right). When the arc gets too long and unstable, its current drops, and do does the solenoid current. This will break the equilibrium and the spring will activate two switches. Those will move the upper electrode closer. If the arc is too short (thus being less efficient), the higher current will cause the solenoid to pull the rocker stronger than the spring does. It'll activate the other two switches, moving the upper electrode further from the bottom, non-moving electrode.

The whole beauty of that mechanism is the constant adjustment of the arc. While the first carbon arc were created with fewer devices and techniques available, there are everything needed today to create a precision mechanism, with a worm gear and slide rail. The H bridge shown here will control a DC motor with a worm gear. This motor will move a slide rail up and down.