banedon wrote:
Isn't 0.1uF actually 100nF?
Yep!
Late night message and not doing the math correctly! Also, I myself never refer to capacitor sizes in nanofarads. They are either farads, microfarads or picofarads in my little brain. In fact, when I started out in electronics, measurement in picofarads didn't exist. The measurement was MMFD for micromicrofarads.
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With regard to larger caps; I put a 33uF tantalum cap in on my last project. I read that tants are faster reacting for their capacity which is why I used one.
Tantalums are good—better, actually, than electrolytics of the same capacitance—but tend to be pricey compared to low ESR electrolytics. That said, I use tantalums for the charge pump capacitors used with the MAX232-248 transceiver series, as their size and low leakage are attractive in that application.
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Do you recommend concentrating on low ESR and possibly a different type?
Low ESR electrolytics are superior to standard ones, and are the better choice in digital design. However, you should note that their high frequency bypassing characteristics are not as good as ceramic, micas, etc. The main purpose of using electrolytics at various points is to "stiffen" Vcc. You should also have a bypass capacitor at each chip, with the shortest leads practical. If using a 7805 (or similar) regulator to power your unit place a 1000 µF electrolytic on the output side as close to the regulator as possible and also bypass the electrolytic with a 0.1 µF ceramic. This will give you the cleanest and most stable voltage.
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Also, my previous design was simple: 1x65C02, 1xEEPROM, 1xRAM, 1x65C22, Oscillator + small amount of glue logic. Does such a design require just the one or would you normally put in X amount per IC much like the smaller bypass ones?
It would depend on the physical layout and construction method. If you are doing it in wirewrap and using a star topography for Vcc and Gnd distribution, consider putting an electrolytic at the far end of each power distribution leg. Also, try to use heavier gauge wire for power distribution instead of the use 30 AWG wirewrap size. Your goals are to minimize ground bounce and Vcc fluctuations.