Quote: Originally Posted by ICit2lol
...Yep Jeannie I wonder why you missed the air caps in the quiz cos that was what you were using .
The tiny ones we called trimmers - I used to be fascinated by how one could "trim" with those things
Variable capacitor - Wikipedia, the free encyclopedia
As I explained earlier (or I think I did), I haven't seen air gap variable caps used in tuned circuits in fifty years and, back then, only the older style, tube powered equipment had them. Even trimmers had solid dielectrics, same as the tuning caps used in smaller radios. TV tuners had fixed tuned circuits that were switched in and out by being rotated on a drum and used solid dielectric trimmers to fine tune them. My old Heathkit didn't even use trimmer caps on the IF and other fixed circuits; you tuned them by screwing a ferrite core in and out of the coil.
During college, I was too busy trying stay afloat in my classes (I have ADHD, which nobody knew anything about back then; ironically I wound up majoring in Psychology) and, after college, I was too busy trying to make a living to be involved with electronics anymore. Being color blind really limited my ability to work in that field. I challenged the Basic Electricity class (took a test instead of actually taking the class: I did the same for Basic Woodworking Hand tools and aced that one), the only electricity class offered at the college I went to (I had planned on transferring after the first two years), and got only a C because I couldn't read the resistor and mica capacitor values because of my color blindness, even though I knew what the color code was. So, the only air gap caps I've seen in use for the last 50 years have been in antenna circuits for car radios and broadcast antennas and the question was asked in the present tense. As I said, the test was poorly laid out. The person who wrote that test would have flunked my college Psychology Tests and Measurements class.