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  1. crutschow

    Can I replace cr2032 powered devices with AAA or li ion?

    But isn't it often used to find the keys at home? Why would you need it when you are out, where the keys are usually in pocket or purse?
  2. crutschow

    Can I replace cr2032 powered devices with AAA or li ion?

    It may be the receiver part, which always needs to be on.
  3. crutschow

    Can I replace cr2032 powered devices with AAA or li ion?

    Those are not rechargeable.
  4. crutschow

    Can I replace cr2032 powered devices with AAA or li ion?

    How about a CR123A 3V lithium? It has a 1500mAh capacity vs. the CR2032 225mAh rating, so should last at least 6 times as long. Alternately the largest coin cell is the CR2477 with a 1000mAh capacity, for about 4 times the life of the CR2032
  5. crutschow

    Op amp comparator troubles

    No. The LM2903 comparator (not an op amp) has an open collector output, so can operate fine with the output connected to a voltage different from its operating voltage. I suspect a wiring error. Double check all your connections as compared to the wiring diagram.
  6. crutschow

    Op amp comparator troubles

    The pull-up resistor (e.g. 10kΩ) needs to go to the +12V to turn off the P-MOSFET.
  7. crutschow

    Convert 1 phase to 3 phase by using an old washing machine

    The output frequency of those is much higher than 50Hz, so would not work to power the pump.
  8. crutschow

    Convert 1 phase to 3 phase by using an old washing machine

    I don't see anything from the washing machine that would generate enough power for your well motor. So you had three live power lines to your property from the power company, since that's the only way you could have 3-phase power? It's rare for a home to have 3-phase power. Are you sure it it...
  9. crutschow

    shaded pole evaporator fan motors

    But what airflow is the motor housing exposed to?
  10. crutschow

    shaded pole evaporator fan motors

    Since most of the mechanical energy goes into moving the air, which is then converted to heat, I fail to see how that would be a "small portion"?
  11. crutschow

    shaded pole evaporator fan motors

    But isn't there an outside air connection for the condenser? There's no free lunch. That mechanical energy is converted into heat by the fan moving the air, which heats the air.
  12. crutschow

    shaded pole evaporator fan motors

    I assume some of that is for the compressor motor that generates the cooling. And depending upon the design, the fan motor heat is likely dissipated in the outside air flow, not the cooling flow.
  13. crutschow

    Increase the amperage fo PNP transistor

    You only need two transistor to form a Darlington, why are you using three?
  14. crutschow

    Increase the amperage fo PNP transistor

    But that's not with the transistor in saturation. BJT's are typically specified for saturation with a base current 1/10th of the collector current.
  15. crutschow

    Increase the amperage fo PNP transistor

    For 350mA (not mAh which is battery capacity) through the collector, the base-emitter current should be at least 35mA. If your circuit cannot provide that much base current, then you will need to add another transistor (for example to make a Darlington stage).
  16. crutschow

    Why does zener voltage decrease as series resistor increases?

    A Zener is not a perfect regulator. Its voltage will change some with a change in current through it. Look at the value for the Zener impedance to determine what the change with current will be. A much better regulator is an IC that mimics a Zener, such as the TL431 shunt reference. It can be...
  17. crutschow

    automatic forward reverse motor with limit switch and relay

    Okay, I missed the "pause" request. How long is the pause?
  18. crutschow

    automatic forward reverse motor with limit switch and relay

    I assumed that would be a standard plug-in timer operating from the mains to power the supply. I see no reason to do anything custom.
  19. crutschow

    automatic forward reverse motor with limit switch and relay

    No error. Yes, the "little down arrows" are standard schematic common/ground symbols, which is the negative connection for the 12V supply. Virtually all mechanical relays are break-before-make due to the way the contact mechanism works. There is a movable contact (the wiper) which moves between...
  20. crutschow

    automatic forward reverse motor with limit switch and relay

    I forgot to add a diode across each relay coil to prevent arcing from the coil inductance across the limit switch's contacts when they open. See below:
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