Sunday, February 5, 2017
Some electronics fun...
The stuff you see there is the regulated 5V power supply for the electronics, plus the touch sensor. The little wire visible coming out from under the top of the vector board will connect to the knob. The blue 20-turn potentiometer adjusts the sensitivity of the circuit. The funny thing with a white cap below the potentiometer is a switch, for resetting the touch sensor chip if it gets stuck. The chip is the tiny little black rectangle with six leads just above that blue potentiometer. It's the smallest component of all – smaller than the quarter-watt resistors and absolutely dwarfed by the 0.47 microfarad capacitor (the green monster on the right side).
It's kind of mind-boggling for this old fart just how small this stuff has gotten. I can still remember (not very fondly, actually) when I did all my electronic construction using lug strips and point-to-point wiring, most resistors I used were huge 5 or 10 watt things, and the active components were vacuum tubes with sockets an inch or more in diameter. Things sure have gotten much smaller!
Much to my amazement, when I finished wiring all this stuff and fired it up, (a) there was no smoke in the air, and (b) it worked on the first try!