By Larry Mundinger <LarryM @ se.rr.com>
Long ago, when I was single, I lived in an apartment across the street from where a slot car track opened. This was the mid 60's and the rage was building or buying little electric powered race cars that ran on a slotted track. Adults would go to these places, rent track time, and see how fast they could drive their cars around the track without spinning out. This was before video games and for a while it was a popular sedentary mindless activity.
I bought a car kit and put it together. Being poor and cheap, I didn't want to spring for the cost of the controller which was a heavy duty variable resistor so I improvised. The apartment building had a small laundry room. Most of the time the washing machine was broken and when it was working people would abandon their loads for hours before returning to transfer them to the dryer. There was a mercury switch on the washing machine lid that cut the motor power when the lid was raised. A mercury switch is a closed tube containing a blob of mercury and having electrical contacts at one end. When the mercury is on the end with the contacts the circuit is closed. When it is tilted so the mercury flows to the other end, the circuit is opened.
I cut the mercury switch out of the washing machine, bypassed it, and installed it in my slot car. It was mounted at an angle so that when there was sufficient lateral acceleration the mercury would move up the tube and power to the motor would be cut. As the car rounded a curve, centrifugal force would move the mercury up the tube and cut power to the motor. As it slowed, the mercury would flow back under the influence of gravity and the motor would again receive power.
I took the car across to the track along with a piece of wire with alligator clips on each end to take the place of a controller. It was necessary to select a track with only left turns because there was only one washing machine and only one mercury switch.
When the mercury switch was properly adjusted the car would zip around the track and when it came to a curve it would slow down, somewhat jerkily, and then burn out on the straightaway. Having no controller to operate, I would walk around the track and observe the car successfully making the curves at a maximum rate.
After a while people would gather around in amazement.
"Where's your controller?" "How do you do that?"
I would reply: "It has an inertial guidance system." It was true. Inertial guidance systems include accelerometers and the mercury switch was a crude accelerometer. This was about 20 miles from Cape Canaveral so most people had heard the term.
It was great fun and I wish that I could think of an equivalent present day spoof to pull.
