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  1. AnalogKid

    Step Up Converter?

    Even with synchronous rectification it will be difficult to reach 90% efficiency, so that 40 A is at least 45 A, and probably closer to 50 A. ak
  2. AnalogKid

    Newb looking for help: Connecting phone to old speakers [pictures included]

    https://en.wikipedia.org/wiki/LaserDisc
  3. AnalogKid

    Need help with long distance circuit

    Given that the float switch is a dry contact, this should not be so much work. At first it sounded like the switch had failed and is closed all the time. If you're sure that's not it, then the only other option is noise pickup. Even at 1/2 mile round trip, it takes a lot of noise *current* to...
  4. AnalogKid

    Drive two relays based on input voltage.

    That is, like, soooo 15 posts ago. Updated schematic solves all of the problems in this universe, but my link to that system is down. ak
  5. AnalogKid

    Drive two relays based on input voltage.

    Rorschach...
  6. AnalogKid

    Drive two relays based on input voltage.

    Only if this is a ratiometric control system, which is not stated in any of the posts. I completely get the advantages of a ratio-based comparator structure, and have used it many times. But the term "computers" opens the possibility of A/D converters looking at the voltages, and they might...
  7. AnalogKid

    Drive two relays based on input voltage.

    No, it doesn't. The deadband depends on the fact that resistors in series guarantee mutually exclusive node voltages. R3 must be adjusted to a voltage at least 20 mV greater than R2 to cover offset voltage errors, and the operational values are over 30 times greater than that. Because the two...
  8. AnalogKid

    Drive two relays based on input voltage.

    First pass at the circuit had an LM358, which does not need pullups. Either way will work. a 1 digit change in 2.07 V is less than 0.5%, pretty specific to trust to an unknown reference source such as the 5 V supply. The 4040 is available down to 0.1% off the shelf. ak
  9. AnalogKid

    LED Strips Display driven from 555 / 4017 counter

    I know the 4093. The 4093 is a friend of mine. The 4093 is one of the all-time great CMOS parts, and I routinely suggest it as an alternative to the 555. BUT - the circuit described in post #4, with a single resistor and capacitor forming a symmetrical square wave oscillator, can be done with...
  10. AnalogKid

    Phone line (modular wire) wattage capacity

    Yes. 28 ga. wire has about 66 ohms of resistance per thousand feet, so a 10 foot long wire pair would have a total resistance of approx. 1.3 ohms. At 200 mA that's a voltage drop of about 1/4 volt. Not great, but the camera should be able to run on that. If you have an extra pair and can run...
  11. AnalogKid

    Drive two relays based on input voltage.

    The deadband between the two comparators is the fancy part. ak
  12. AnalogKid

    Drive two relays based on input voltage.

    What you describe is a window comparator. Here is a first pass. It needs input transient protection, decoupling, etc., but gets the idea out for discussion. ak
  13. AnalogKid

    Drive two relays based on input voltage.

    Assuming the relays are 12 V, what is the current for each one? And is SPST ok? ak
  14. AnalogKid

    Drive two relays based on input voltage.

    This is an easy job for an LM393 dual comparator. Unfortunately, it will not require any programming, Just to confirm a third time, there is a dead band between 2.07 V and 2.70 V where neither output is activated, correct? ak
  15. AnalogKid

    Solar lights to DC

    All information is useful. Yes, the connectivity of both the batteries and the LEDs are needed to reverse engineer a power system. part of the problem is that solar panels are inherently self-limiting - as you draw more and more current, the output voltage goes down. A small AC/DC power supply...
  16. AnalogKid

    circuit help

    It was an either-or question. Yes is not an answer to an either-or question. Pay attention. Also, there are no standard schematic symbols in the image, and no clue as to what it is, how it is used, what the voltage tolerances are, etc. ak
  17. AnalogKid

    circuit help

    Are the 5 V and 0 V outputs logic levels, or do they have to be exactly 5.00 V and 0.00 V? ak
  18. AnalogKid

    Making new AC DC transformer for La Z Boy chair

    Shell.
  19. AnalogKid

    Making new AC DC transformer for La Z Boy chair

    If by "build my own transformer" you mean getting some grain-oriented steel stampings, a bobbin or two, and a pound of magnet wire (two different sizes) and winding a transformer from scratch - I strongly recommend that you don't. Even if you got it to work (a very big if), there is no way it...
  20. AnalogKid

    What component does this symbol represent?

    That is National's standard symbol for a constant current source, something that takes 2 or more transistors. ak
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