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  1. crutschow

    Change 3 phase Steam Boiler to 3 phase Hot Water Boiler?

    A single-phase thermostat controlling a high-current 3-pole contactor (relay) may be cheaper.
  2. crutschow

    output of power supply reads 24V should be 12V

    To add to the info on the sense lines, they are the feedback connections that determines the output voltage, so they must be connected to the output terminals to get the correct output voltage. If they are not properly connected than the output will go to the maximum voltage the supply can output.
  3. crutschow

    Wire Size for Security Camera

    The cameras should have a power rating in their specifications, but the power draw is likely quite small (a few watts). 18Ga wire should be sufficient, even for the 80 foot run.
  4. crutschow

    Temperature Probe Testing

    Hard to say. I see no mention of how long it can provide power. I suggest a wide mount vacuum, bottle such as this, to store the water. It should have a minimum heat loss to ambient. You can heat it to temperature from the mains, and then use a battery powered heater to maintain the temperature.
  5. crutschow

    Soldering temperature indicator

    What laser? The IR temp gun uses a passive IR detector to determine the temperature from the radiated IR energy.
  6. crutschow

    Strategy for Over Voltage

    A common overvoltage detector is crowbar circuit that uses a voltage detector to trigger the SCR and short the output to ground in a few microseconds when the overvoltage occurs. That then typically blows a fuse or puts the supply into current limit. You then have to remove the voltage to reset...
  7. crutschow

    Temperature Probe Testing

    My calculations show that it would take 10WH to keep the water at a steady temperature, so the battery would have to supply 10WH of energy over a 30 minute period. So a 12V battery would need to supply 20W or about 1.7A continuously. The size battery will be determined by how long you need to...
  8. crutschow

    How to calculate appropriate parameters for flyback diode?

    How long is that "fraction of a second" 5W times that time will tell you the surge energy it can absorb.
  9. crutschow

    Temperature Probe Testing

    Water takes a lot of energy to heat, so a battery powered system would likely require a healthy sized battery heating a minimum amount of water in an insulated container. For example, it takes 55 watt-hours to heat one quart of water from room temperature to 170°F. This would require 10A from a...
  10. crutschow

    Temperature Probe Testing

    Don't know if it would work or be accurate enough but you might look at an electric sous vide machine used to heat water in a pot to a controlled temperature for cooking.
  11. crutschow

    How to calculate appropriate parameters for flyback diode?

    That's a low inductance for a solenoid. The energy stored in an inductor is 1/2 LI² where L is the inductance and I is the current. So for 0.9A through that inductance, the stored energy (which is dissipated when the solenoid is turned off) is 0.582 milliJoules. If the solenoid is operating at...
  12. crutschow

    How to calculate appropriate parameters for flyback diode?

    That would be the peak power when the injector turns off, not the average power. To determine the average power, you need to know the injector inductance, and the maximum frequency of operation. An alternate for fast turn-off (but not quite as fast as the Zener) would be to use a regular diode...
  13. crutschow

    Why I need a capacitor in parallel to micro limit switch

    A capacitor across switch contacts can lead to pitting and welding of the contacts due to the large instantaneous capacitor discharge current when the contacts close. It acts like a small-scale spot welder.
  14. crutschow

    Peak Power and Nominal power of motor

    Yes. But you will need to include a time-limit in the software so the peak power time is not exceeded for the motor you have.
  15. crutschow

    Peak Power and Nominal power of motor

    That makes little sense. How can you achieve higher speeds without that increasing the load?
  16. crutschow

    Peak Power and Nominal power of motor

    No. The motor power rating is determined by the load. Operating at a power rating of 1kW requires a load on the motor that draws 1kW from the mains. (The load would be slightly under 1kW, depending upon the efficiency of the motor).
  17. crutschow

    Easy pulse generator

    Do you need the circuit to operate whether the input pulse is both shorter or longer than the desired output pulse?
  18. crutschow

    Diode Characteristic Graph

    As an aside, here's the LTspice simulation of an interesting circuit similar to a voltage reference circuit I saw many years ago (I think in EDN). It uses the amplified reference voltage to bias the reference source current (sort of a bootstrap), which stabilizes it with respect to input voltage...
  19. crutschow

    Diode Characteristic Graph

    I doubt that it's deliberate. It's just that the instructors have had little or no experience in designing real circuits.
  20. crutschow

    Blown up two laptops

    Not sure what is happening, but it sounds like there is some sort of voltage/ground problem when the USB is connected. So I suggest you look for an isolated USB connection (something like this), which should prevent any problem from that (or at least if it fails, it's a lot cheaper than...
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