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  1. M

    difference between Icc and Ic ??

    Cool. I suppose that would mean that at some point I might see an Iee(max) were the transistor to be a PNP. Thanks for confirming my suspicions. :)
  2. M

    difference between Icc and Ic ??

    here is the exact wording of the problem: "Design a circuit using voltage-divider bias for the following specifications: Vcc=9 v, Icc(max) = 5 mA, Ic = 1.5 mA, and Vce = 3 v. The transistor is a 2N3904." I think they mean that the overall circuit, from Vcc to ground should only have 5 ma...
  3. M

    difference between Icc and Ic ??

    I'm working on a section on biasing transistors, and nowhere in the text up to now do they mention Icc. But suddenly in the homework problems, there is mention of Icc. What does this term mean, and how is it different than Ic? Thanks,
  4. M

    i need help understanding this simple circuit

    so here's a simple voltage doubler, 2 diodes, 2 caps, should be a breeze, right? But I'm having a hard time understanding exactly how this circuit works, and I'd love if someone would just walk me through it, from time 0 through as far as you care. What really confuses me is the big current...
  5. M

    measuring inductance brain teaser

    So I went back out to the lab to try some other methods. I found a couple more websites that offer easy solutions. This one seems to work well for inductors under say 200 µH: http://www.dos4ever.com/inductor/inductor.html and this one did well regardless of the size of the inductor...
  6. M

    measuring inductance brain teaser

    hmm, interesting. OK, I will try the above tonight when I get home from work. Meanwhile, here is the website I got that formula from. Is it wrong, or did I miss some step in my explanation? http://daycounter.com/Articles/How-To-Measure-Inductance.phtml
  7. M

    measuring inductance brain teaser

    So I'm going thru my labs on reactance, and my measurements are coming close, but not really close enough for my tastes. I realized that I'm just assuming the inductance value from the code on the side of the inductor, and not actually measuring it. So, out of the many ways to measure...
  8. M

    need suggestions for next textbook

    that's a great idea. We could also have a little section for the known typos (esp. in the homework problems) since the publishers never seem to care to fix those from edition to edition. Set up the sticky and I'll give you a hearty review of "Introduction to Electronics" by Stephen Harsany...
  9. M

    need suggestions for next textbook

    yeah, i'm looking forward to having a clue about what they're talking about. ;) So I found the Floyd book (textbook and lab manual, 8th ed.) on the barnes & noble site for under $40 with shipping, so I'm going to dive into that. The runners up / possible future reads were: "Electronic...
  10. M

    need suggestions for next textbook

    I have the Art of Electronics, and one day I'll be ready to go through it. But as an example of the way I think AoE breezes through the fundamentals, the topics covered in the 500+ page book i just went thru are given just 12 pages in AoE. AoE is the deep end of the pool for me, and I'm not...
  11. M

    need suggestions for next textbook

    so i'm finishing up my "introduction to electronics" textbook, and I'm looking for suggestions on where to turn next. the book I just went thru started at the basics, ohm's law, kirchhoff's laws, series / parallel resistors, network theorems (mesh, nodal, etc.), transformers, caps, and...
  12. M

    simple transformer impedence circuit

    cool, thanks harald. like I said, the typos in this book are many, especially with regard to the answers in the back. I may post a few of the more egregious examples later so at least if someone googles it, there may be a resource to get the correct answer. cheers!
  13. M

    simple transformer impedence circuit

    so I'm going thru "Introduction to Electronics: DC/AC circuits" by Stephen Harsany, and it's great, but the typos are killing me! So I need help determining if the text leaves out a crucial piece of info. Given a primary circuit with an AC voltage of 10v, a resistance of 200 Ohm, and a...
  14. M

    how long do various capacitors last?

    As I understand it, the issue with this keyboard is not so much that the tantalums are a bad capacitor medium, it's that the circuit design was abusive to them. They experienced high reverse voltages, and also transient spikes from a poorly designed power supply, and I think over the years it...
  15. M

    how long do various capacitors last?

    ha, so obvious! thanks!
  16. M

    how long do various capacitors last?

    Thanks for your help Dave. and... well, that's just it. it isn't working. there's two sections to this keyboard, a "string" section, and a "synthesizer" section. The synth part isn't working at all, but that's probably due to a fried CMOS somewhere, probably an op amp. The keyboard as a...
  17. M

    how long do various capacitors last?

    here are the requested photos. the first one is of the 22 uF caps. The next is just a larger zoom out of the lower voicing board. I think this synth was manufactured between 1977 - 1979. So could be a little later.
  18. M

    how long do various capacitors last?

    yeah, i've heard tantalums can last a while, but if you look at any of the documented recaps of the Arp Omni (mk. 1) on the web, they all say that the tants start leaking and causing stuck notes and other mischief. This particular keyboard was notorious for having a poorly designed power...
  19. M

    how long do various capacitors last?

    i'm about to dig in to repairing an old synthesizer (Arp Omni) from 1977, and I know I need to replace the tantalum capacitors, and I'm going to replace all the caps in the power supply, but on the lower voltage boards (+/- 15v) I'm wondering whether I need to replace the ceramic disk caps, and...
  20. M

    can someone idiot proof this simple circuit?

    The label is even hard to read while holding it two feet in front of you. RS-380SH RD542/15 (although that slash could be a Y) made in china I think I'm going to get a 1/2 watt pot and a 3300 ohm resistor and go with that. I should point out that I will only be operating this circuit for...
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