The Toy Shocking Machine, in all honesty, is a primary reason I chose to construct projects from the 1915 book Home-Made Toys for Girls and Boys for the upcoming 2016 Newark Maker Faire. The innocent nostalgia transports to simpler times when children were encouraged to challenge themselves and explore their world without restraint. Maintaining youthful spirit I imagined owning a device to shock myself, friends, family and strangers for entertainment. I’m old enough to remember similar devices making a splash at amusement parks and science class.
With giddy anticipation I started constructing the heart of the device, the induction-coil. The coil consists of two windings of different gauge wire around an iron bolt. A rapidly interrupted flow of electricity is applied to the central primary coil to create an oscillating magnetic field which, in turn, creates high voltage across the outer secondary coil. The high voltage discharges between the two ends of the secondary coil in the hands of a volunteer.
In hindsight it’s easy for me to parrot the above information and sound as though I know what I’m talking about. I enjoy tinkering with hobby electronics however my understanding is often limited. When I attached the coil to a battery I was baffled as to why it wasn’t shocking me. Confused, I texted electronics genius friend Charlie England. He responded “…you have to apply voltage and remove it very quickly…” I hastily constructed an interrupter as described in the book. Turning the crank created an entertainingly loud racket and a few sparks, but nothing shocking from the secondary coil.
Charlie suggested testing the electromagnetic properties of the coil. I grabbed a small washer, verified it was steel with a real magnet and applied power to the coil. Nothing, the washer fell to the table without hesitation. The only thing that made sense was to apply more power (amps). Working in increasing intervals I finished with two 6-volt lantern batteries in series attached to the coil. No electromagnet but plenty of heat – which is undesirable. Defeated, I informed Charlie I was going to make another coil. He responded with four words, “Send me the coil.” Yessir, the coil was packed and on its way the following morning.
After receiving the delivery Charlie went to work testing my induction coil. The coil only created a 90 volt spike using a 10 volt power source. Charlie determined the secondary coil needed triple the amount of wire layers to generate a palpable shock. Charlie also designed and created an interrupter circuit employing a proximity switch. It was left to my imagination on how to integrate this interrupter circuit into the device. Because the proximity switch detects ferritic material I created a wheel with thumbtacks placed at fixed intervals around the perimeter. When a thumbtack passes under the proximity switch the switch turns on, when the thumbtack passes the switch turns off.
I added several more layers of wire to the coil, attached it to the new hi-tech interrupter and with a little fussing around, success! A tangible shock was felt when the interrupter was engaged. Knowing the coil was working correctly I built the third and final interrupter for the circuit integrating wooden gears to increase the switching frequency. Everything works like a charm. I will continue tinkering with this device leading up to the Maker Faire to ensure an entertaining and dependable experience.