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  1. AnalogKid

    Zener Diode

    https://en.wikipedia.org/wiki/Zener_diode ak
  2. AnalogKid

    reed switches

    Gauss's Law for magnetism, translated into English: There is no such thing as a magnetic monopole. Maxwell's Equations actually numbered around 20. Oliver Heavyside condensed them down to the fab four we know today, and basically invented vector algebra to tighten them up. This one usually is...
  3. AnalogKid

    RS232 / TTL converter pin4

    Maxim, LTC, and TI have huge numbers of other parts, single chips with enough circuits in them for a full RS-232 interface. ak
  4. AnalogKid

    sample and hold pulse source?

    The dead band window of hysteretic CMOS parts (40106, 4093, 74AC14, etc.) is not tightly controlled. While CMOS timer circuits frequently are more convenient than 555's, they also are much less accurate over temperature and part-to-part variations. Many CMOS parts have a "typical" value of 33%...
  5. AnalogKid

    sample and hold pulse source?

    An R-C differentiator can turn an edge into a spike. And it can be a pretty narrow, fast spike, fast enough not to need a Schmitt trigger to clean it up. A 50 us spike probably is fast enough. But if you want the added security of a Schmitt trigger using non-Schmitt inverters, connect two of...
  6. AnalogKid

    sample and hold pulse source?

    My life is complete.
  7. AnalogKid

    RS232 / TTL converter pin4

    Are you looking for a complete product, or a chip? ak
  8. AnalogKid

    I need a looping digital timer

    There are a TON of timer modules on ebay. Here is one with digital settings for $9. Or you can follow Steve's idea - two 555-based timer modules can be tied together to form a cycle timer for about $3. No soldering. ak
  9. AnalogKid

    Detecting a change in signal

    The window (dual) comparator method is reliable, and independent of the signal rate of change, overall bandwidth, etc. And with open-collector comparators you get free output combining. But it does use up a few parts. When you say "deviate", how fast? Are you trying to detect a relatively...
  10. AnalogKid

    Diodes failing after getting really hot. Attached to UPS system.

    Yes, but not after years of normal operation. Some downstream systems do not like the squarewave AC from a low cost UPS, but that usually shows up in a few hours (or *much* sooner). And while we're focusing on the UPS, what kind is it? More importantly, did the failures occur when running on...
  11. AnalogKid

    I need a looping digital timer

    Battery or line powered timer? Battery or line powered load? Weather/waterproof or indoor office? So many secrets. So many timers. ak
  12. AnalogKid

    Diodes failing after getting really hot. Attached to UPS system.

    Without any information on the UPS model or output type or load, it's kinda hard to say. 1. If this is in one installation only, and everything that fails is connected to the ups, how hard is it to swap in a replacement ups for a while and see if the problem continues? 2. When the failed...
  13. AnalogKid

    How to time a watch winder

    The 555 is a wonderful little critter, but I've never liked to use it with large timing caps. The early parts were weird with anything over about 10 uF, and 100 uF was trouble, and back then a 2.2 uF ceramic was real money. Of course the newer CMOS parts are way better, but old habits...
  14. AnalogKid

    How to time a watch winder

    Wrote this yesterday, didn't hit Post. The diode effectively reduces the terminal voltage for the charging capacitor by 0.6 V during the charging phase, by over 10% for a 5 V circuit, or by 5% for a 12 V circuit, but it does not reduce the voltage at the top of the 555 internal reference...
  15. AnalogKid

    14040 Counter help please

    I can't say what the outputs do outside the drawing fragment, but you've got the logic right. The two diodes and R67 form an and gate. Counting up from 0, Q4 pulses several times before Q8 goes high for the first time. Once Q8 is high, when Q4 next high both diodes are reverse biased and R67...
  16. AnalogKid

    How to time a watch winder

    Alternate output timing. ak
  17. AnalogKid

    How to time a watch winder

    I bounced out to Digi-Key and looked at some large cap datasheets. Leakage current calculates out to around 500 uA, which is greater than the charging current through a 390K resistor at 12 V. Also, the NE555 has much higher input currents than the CMOS version. All of this could add up to the...
  18. AnalogKid

    Energy production

    A dynamic microphone does this. It converts changes in air pressure (sound) to electric current without requiring any kind of external energy source to do it. Note that for normal speech a dynamic microphone produces approximately 5 mV across 600 ohms, or about 42 nanowatts. In round numbers...
  19. AnalogKid

    D-Sub crimps

    Interesting detail to leave out. The majority of pre-crimped leads on the market are surplus. New, unused, etc., but also from an uncontrollable source using unknown parts and having unpredictable long term supply. For a production environment, nothing can match the flexibility and control...
  20. AnalogKid

    A Quick Question About Cadence

    Last I heard (5 years ago?) Cadence runs on all major platforms. ak
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