Here’s your video introduction to Section 5.1, Semiconductor Devices, in the ARRL Extra Class License Manual for Ham Radio.
After you’ve reviewed the video and studied the material in the text, you may return to the list of Amateur Extra videos by clicking here.
P.S. The periodic table of elements shown in the video is from Wikipedia. The attribution in the video is not clear.
Dave, Needless to say, I thoroughly enjoy your lectures. I am a retired real estate appraiser thus I am not a techie. My question is this: What is “Bias” and “Reverse Bias”? How is it created and where does the voltage come from?
Steve
You are correct: putting a DC voltage across a bypass capacitor will indeed charge it. Usually these capacitors have very low value, so the DC charge is not big, and anyway the charge, once the circuit is turned on, stays constant. There is another item to note, however, which is that the capacitor affects the input and output impedance of the MMICs. Given the frequency at which they operate, a simple wire can have enough inductance to create an unwanted resonance and a haywire impedance. That’s why the physical construction of MMIC-related circuits is so important, as shown in Figure 5-24.
Dave, thank you so very much for this video. As you no doubt know, mastering an engineering subject is often a series of small epiphanies, and this video is the first time that anyone has simply straight out explained that putting a capacitor in series with ground effectively blocks a particular path to ground for DC but not AC, and this is also the first time I’ve encountered that a diode in the conducting state admits AC! This has suddenly demystified a number of different schematics I’ve looked at and failed to understand.
Question:
re MMIC’s
“DC see’s a cap as an ‘open’ , where AC goes right past”
DC to a cap should charge it , and discharge presenting a pulse no? Or am I inserting a path to discharge it that is not there? With out a discharge path the dc just charges it and sits there blocking the dc after that?
Yep, Just trying to see how much of the material I can retain, before losing sleep on the math. I pretested , to within 4 of passing (before reading the book hehe). I’m going to be taking all 3 elements monday. I can live with only passing 2 the first round 🙂 Your videos have been extremely helpful. Where words on a page defeat my photographic memory, hearing the material, is much easier to retain.
You may want to slog through the math session because of the key concept of phase angles—pretty important stuff.
Thanks Dave! Been grinding all three elements for the past two weeks. This is where I sit now. (I skipped the math section)