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  1. duke37

    Automatic chicken coop door opener

    Your light detector may have a dead band (Schmitt trigger) which can be adjusted to stop false triggering. The time constant of a resistor-capacitor combination cannot go above several seconds due to leakage in the capacitor, you could try 1000uF or even 10000uF.Checking that the chooks are in...
  2. duke37

    Automatic chicken coop door opener

    The light switch looks like a good idea. How do you ensure that the chooks are inside before the door is closed? Could you put a microswitch under their perch? Does your motor reverse when the supply is reversed?
  3. duke37

    well water level measure

    If the well is line of sight, you could use a semaphore system to give a visual indication. Alternatively, you could go to radio control. What range would a TV zapper have if given a large parabolic reflector each end?
  4. duke37

    Automatic chicken coop door opener

    I have tried to engage a brain cell. Here is how I think it could be done if you have a permanent magnet brush motor which will reverse with reversed polarity. You will need two timers, one to raise and one to fall. You may be able to get away without the relay if your timers have more contacts.
  5. duke37

    Automatic chicken coop door opener

    Is this a repeat of a previous post? I suggested then to use a car window mechanism which will run off 12V and have limit switches to define up and down.
  6. duke37

    Detecting over voltage charging

    A diode in the output of the generator will drop somewhere between 0.7 and 1V. This would give a more reasonable voltage. Depending on the current, you may need a big diode with a heat sink. A possibility is a diode bridge where you can select either one or two diodes and it can be bolted to a...
  7. duke37

    back up battery for mains supply???

    Have you considered an engine/generator to automatically switch in?
  8. duke37

    Motor Load detection

    A resistor and comparator can detect when the motor is stalled but the current will be turned back on unless a latch of some sort is employed. The latch would need to be reset when the power is removed. If the motor is reversed by reversing the polarity of the supply, then this will also need...
  9. duke37

    In search of a FET

    I have used the IRF540 at several amps with 10V drive. I have not checked what drive is required. A P channel mosfet from the same maker is IRF9Z34, I have not used P channel mosfets. There is a trade off between voltage capability and on resistance so at low voltage you can get a low on...
  10. duke37

    Capacitor in Florescent Lamp

    There is no purpose in the power factor. it just is. What is the purpose of the resistance of a wire? Why do you wish to reduce the power factor to 0.791? The ideal power factor is 1, By using different (smaller) capacitors, you should be able to plot power factor against capacitance to...
  11. duke37

    In search of a FET

    There are many FETs which can do the job. one that seems to be refered to more often than others is IRF540A, details can be found on the net.
  12. duke37

    Capacitor in Florescent Lamp

    The capacitors in fluorescent light are as Resqueline says primarily to correct the power factor. These are connected across the supply. They also help on switch off, reducing the arc in the switch due to the inductance. I had a fluorescent fitting which had the capacitor in series with the...
  13. duke37

    SMS Controller timed output problem

    I doubt if the staircase timer is the trouble, if it will work in a large building with long input wires, it should be immune to stray input pulses. Would it be possible to check that your relays are not re-triggering? Better smoothing of your controller power supply is probably the way to go...
  14. duke37

    power supply

    Running a transformer or other inductive load from a light dimmer is not considered good practise since it is possible to get saturation if equal positive and negative pulses are not obtained. It can work if the load has a fairly high resistance but here you are driving quite a large power...
  15. duke37

    SMS Controller timed output problem

    It seems as if you are getting inductive pulses from your motor (AC?) back to your control circuit. If the staircase timer (never heard of this) is driven by DC, then improve the power supply by adding a large elecrolytic capacitor. If it is driven by AC, then a power factor correction...
  16. duke37

    transformer dilema

    With two similar transformers, you can do a bodge. Connect the primaries in parallel to 110V and connect the (now) 9V secondaries in series to give 18V.
  17. duke37

    transformer dilema

    Green to green is 18V which is what you want. The green/yellow is a ceter tap to give 9-0-9.
  18. duke37

    transformer dilema

    Yes. The M1000 is 220V to 18V and will give 9V on 110V in. Presumably this the one to replace. The Allied is 110V to 18V cetre tapped and will give 18V on the two outer connections. Insulate the centre tap as you suggest.
  19. duke37

    transformer dilema

    Which is the new transformer? One shows 220V to 18V, this presumably has only two wires out. The other has the correct primary but looks like a cetre tapped output winding. If you have a 220V transformer with an 18V-0-18V output, it will give 18V out using the complete secondary when fed with 110V.
  20. duke37

    transformer dilema

    Some transformers are made with two primaries which can be connected in series for 220V and in parallel for 110V. The transformer will be labeled if this is so. It will have four primary connections. 50 Hz transformers will be fine on 60 Hz but not necessarily the other way round. If you use...
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