The Door knob electrostatic generator was derived from a combination of the classic Wimshurst design and A.D. Moor’s Dirod.
Besides greater output for it’s size, one of the major advantages with this design is the use of the Tamiya motor gearbox. With the gearing set as described in this manual, the gearbox runs at the perfect speed to produce maximum output. The motor will slow down a bit when there has not been a discharge for a while. This is a good sign that the electrostatic generator has been constructed properly, and that you are getting the highest power that the motor can produce. The motor runs for hours on a single set of C size batteries (depending on brush friction).
Another advantage with this design, as opposed to the Wimshurst, is that there is only one rotating disk. This simplifies construction and reduces the number of things that can go wrong.
This generator reliably generates one inch sparks at a rate of around one per second, any time of year. I have run it in the middle of summer and when it is raining outside. I have never had it fail to start (accept when a brush is broken). The arc length is limited by arcing between the two inductors (boomerang shaped silver sections attached to the door knobs). When the white shorting bar in the picture is moved so that the combined distance from the ends to each brass doorknob is greater than 1 inch, arcing begins between the two inductors. This distance is 2 ¼”, but the edges of the foil cause the air to ionize really well. There are two insulator plates in the design that minimize these arcs, but a substance is required between these sheets to bond them together with an air tight seal. I have tried high vacuum silicon grease (increased to 2” arc), but have not yet tried silicon sealant.
The design of the shorting bar allows it to be picked up from the middle by hand while the generator is running. The shorting bar can then be moved to the desired arcing distance without being zapped.
Some effort was spent on making this generator look really great. This generator can be placed on display in the living room or a bedroom, rather than collecting dust in the garage.Home