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  1. Minder

    Mystery small signal?? transformer?? w part number

    Pulse transformers. I have purchased some from Hammond Transformers, not that part No however. Max,
  2. Minder

    Mystery small signal?? transformer?? w part number

    They may well be ferrite core and are used in SMPS switching, you may have to do a little reverse engineering to determine the usage first. M.
  3. Minder

    Motor run capacitor theroy with added PFC fun

    Without a start winding/cap a 1ph motor current will oscillate at 0-180° hence the rotor does not move, the optimum vector leverage angle from here is 90° VFD's with phase vector operation attempt to keep the current vector angle to 90° throughout the operation for optimum force. It can be...
  4. Minder

    Motor run capacitor theroy with added PFC fun

    If you shift the start winding phase angle 90° look at where it peaks WRT the run winding!. The idea is to create an efficient vector angle WRT to 180° of the primary/run winding field in order for the motor to be able to rotate. M'.
  5. Minder

    Motor run capacitor theroy with added PFC fun

    The ideal is a capacitor value that will produce a 90° phase shift WRT the run winding. It is best to use Motor rated AC run capacitors, usually oil filled paper. M.
  6. Minder

    Playing with valves

    They almost look like dekatron valves, if so we used to use them in counting/timing circuits in the '60's . Gas filled IIRC. http://www.electricstuff.co.uk/dekatron.html M.
  7. Minder

    Electric motor to turn a fishing reel

    You need a small DC brushed motor, you do not need anything very high powered as it will require extra in the way of battery power, there are PWM controllers on ebay for ~$5.00. You would need to get creative to incorporate it into or attached to the handle of the rod. M.
  8. Minder

    convert a 3 phase 1 hp ac motor to 12 vdc

    To run a 3ph 1hp from 12vdc you would need a 12v/240v 1ph invertor, or whatever the motor voltage is. Most VFD's will also run from a 240/300vdc source as the input is a 3ph rectifier. The alternative is a 12vdc motor from a bumper winch etc. M.
  9. Minder

    Wanted: Circuit wizard (standard/ professional or hobby version

    Have you tried the free LTspice? For Circuity Boards/schematics I use Kicad, also free. M.
  10. Minder

    How to ground unwanted AC from a metal case?

    Just out of interest I always make a point of earth grounding any electronics supply in the machines I have retrofitted. Plus any metallic enclosure to conform with equi-potential bonding to the earth star point. Some are PC based for motion control and as most know, the P.S. of a PC also has a...
  11. Minder

    Temperature control

    Solid state (SSR's) can be zero crossing switch on and are on for the whole cycle and are usually used in heating applications by burst firing for short intervals, this is opposed to phase angle control such as motor/rpm control and can be noisy. A proper rated SSR should not get that hot, they...
  12. Minder

    microFarad

    Actually 1MF you would not get in your house! The correct notation is µf. (microFarad). The fractions of which are pico, nano, etc. M.
  13. Minder

    Temperature control

    If you turn a heating element off, it continues to heat as it cools down. PID control is to maintain steady control, without overshoot. IOW as the temp approaches the set point it anticipate over shoot and starts to turn off before the set point, and then on/off at increasingly smaller...
  14. Minder

    Why DC motor draws more current with friction?

    T.M. Treadmill (motor). M.
  15. Minder

    Why DC motor draws more current with friction?

    Most has been covered already. The basic resistance of a DC motor is whatever the commutator including brushes is equal to. Which in most cases is just a an Ohm or two, this results in a very high current if full voltage is applied at switch on, due to this very high current the motor starts to...
  16. Minder

    Why DC motor draws more current with friction?

    The motor generates a voltage the same polarity as the supply so it opposes the applied voltage, for example a 100vdc motor rated at 1000rpm, will generate a voltage of ~100vdc when rotated externally at 1000rpm. M.
  17. Minder

    3-Phase motor clarification.

    Open circuit does not bode well, as previous, they should all be equal. if not, the motor is 'single phasing' which results in a blown fuse/O.L. or breaker. M.
  18. Minder

    3-Phase motor clarification.

    In a 3ph motor the windings presented to the 3 phases should be identical, whether connected star or delta. by 'no' do you mean Normally open? The traditional way of testing is with a clamp on ammeter on each phase, they should all be equal. Is the contactor contacts OK, the contactor itself...
  19. Minder

    Help for a Project please!

    If it is a T.M. motor as I suspect it is, it will output a very smooth pulse free DC output of 0-90vdc when ran at the rated rpm. I have used many of these motors and they traditionally are not that low a pole count where you would see any kind of pulse at low rpm. M.
  20. Minder

    Fluorescent fitting blowing fuses?

    One way is a burnt winding with a short to ground. M.
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