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AUT100C.gif, 15 kB



Before I began designing my remote control system, I began to "kick around" some sensor ideas...

Sensors are important. Sensors connect to everything. Many sensors are in hostile environments, where they may be exposed to high voltage, water, or vibration. I thought of encapsulating sensors in plastic - totally in plastic; Sensors can be made cheap, and therefore can be incapsulated as a throwaway item. Optocouplers and opamps are mear pennies. Even programable logic is cheap. Never ever - ever - repair a sensor. Sensors can be damaged in subtle ways, involving erratic behavior. Inconsistent behavior can not only kill a remote control system - it can kill you! Suspicious sensors should be discarded, as they are terribly important and can jeopardize a good control system.

CARTOONWHICH.JPG, 41 kB A lying sensor is worse than no sensor at all.

When I was a kid, I mounted small insects in plastic. I was not good at it: Too many failures with air bubbles, rot, and such. But I remembered the plastic resin, and reasoned that mounting electronic parts should be a piece of cake. I made my molds out of modeling clay. I bought coloring die to make different colored sensors. The color would be nice for identification as you may not be able to see through the plastic inside the sensor.

I immediately ran into a problem. Some sensors have small adjusting pots. How can you access adjusting pots inside the sensors? Also the epoxy resin would invade the pot mechanisms and freeze the pot solid. The solution was to first incapsulate the pot in silicon grease. The grease protected the pots from epoxy invasion, and made it possible to later drill a hole through the hard encapsulation into the soft grease pocket. A small tweaker could be inserted into the grease for adjustments, and when withdrawn the sensor was still protected from dust.

But now, I had real big problems that could not be overcome. The time was about 1988. I was appointed Chief engineer of the intire station. There was no more time for sensors, much less my control system in general. For twelve hours a day, I "plowed" through paper work. I left my "fun" world behind, and I really missed it. For twelve hours a day, I worried about bills; For twelve hours straight, I neither ate nor drank. No time to eat! And I need not mention the stress! I kept this up for a year, and resigned from the boring managatorial work. (Besides... I was Chief Engineer any way - in practice.) I grew to hate administration duties; and I know that "Promotions" are not always a good thing. You will find that a lot of puffed-out-chests are actually people full of hot air. Hot air may fill the chest cavity, but the condition is mental.
I had to get back to figuring out how to do these "control-things". Sensors were only the first step; Next came the actual control system.