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  1. OperaHouse

    12V DC Motor in Light Fixture with Dimmer & 12V DC to 110V AC Inverter

    I remember hearing of a company that used a 100A power supply just to power a single relay so it wouldn't drop out with short line dropouts. The concept is the same of getting a converter with enough internal capacitance. Are these lights LED? Those typically have a higher voltage they start...
  2. OperaHouse

    Does anyone use NTC resistors to limit inrush current on single phase AC motors as a soft start?.

    The thermistor used is a 5 ohm 20A and they put two or three in series. They confuse limiting inrush with limiting current. They have to use two or three in series because the transition is so fast. At half current the resistance drops to 0.08 ohms. Motor won't do much with 15 ohms in series...
  3. OperaHouse

    Does anyone use NTC resistors to limit inrush current on single phase AC motors as a soft start?.

    The question is commercially. My only experience is with power supplies. I got into a discussion about using these with air conditioners to limit startup current where inverters were unable to take the startup surge. Some have tried it. I thought they might help a little in much the way a long...
  4. OperaHouse

    PV backfeeding the grid

    On solar forums, the discussion of grid tie inverters in the US set up for zero export and exporting power is often a topic. Theories about response time, exporting on one leg and drawing on the other, and setting export too close to zero are discussed. How these machines are set up apparently...
  5. OperaHouse

    Pulse generation

    Some assembly required. First, is this a one shot pulse with a long time between pulses. I pulse heating elements in water heaters and this isn't that hard if there is a time between pulses. Take any standard 80V 6A power supply and put a 6,000uf or more capacitor bank on it. Then drive a...
  6. OperaHouse

    How mount PCB

    I use nylon snap in board spacers for circuit boards with mounting holes in them. One possibility is stamped flat solder lugs which would snap into these spacers and just solder a bare wire to the board in 4 corners. I've not been happy with the dupont pins and connectors making reliable...
  7. OperaHouse

    Solar power research and development project

    I have an off grid system somewhat similar to that. There is only a car battery to provide surge current, could possibly get away with a SLA. Some have used super caps for very temporary storage. I dump excess power to heat water because I have no real battery storage. They have three phase...
  8. OperaHouse

    Help identifying circuit.

    200A! Looks like a welder.
  9. OperaHouse

    When is a schematic proprietary?

    If not specified, you may not get it. A prior managers wife had an online business an after several years was unhappy with web creators service. They tried to cancel only to be told the web designer owned the domain name and if they left, couldn't use it.
  10. OperaHouse

    Help on a darlington

    I'd put a resistor in the emitter of the 13003. Say, maybe 1 ohm. That will give you some current stability feedback.
  11. OperaHouse

    Capacitor only filter for a twitter

    People will listen to anything. Many years back the Infinity 1001 has a 12 inch woofer where the weighted the voice coil with modeling clay. Added to that was a tiny tweeter. It was Tizz, tizz, boom, boom. Big hole in the midrange, but people liked them. I still have a pair of Magnaplanars.
  12. OperaHouse

    Help designing a dimmer

    Triacs and SCR will heat up quite a bit even when operating properly. Back to back SCR are generally used over 20A. Forward voltage is always about 1.5V. Multiplied by 40 so amps is a lot of heat. Good thing you are water cooled. This is not an indication of fault.
  13. OperaHouse

    Generator Winding Heating with solar panels

    There are power point converter boxes that will go right into a resistive heating element if it has one from the panels. Another way off the shelf, you could add a battery to the FM80 (I assume you will be running at night) and get an AC inverter. Find one or multiple transformers to drop the...
  14. OperaHouse

    Capacitor only filter for a twitter

    Actually, many tweeters now are piezo. They call the series capacitor a shelving capacitor. So it is more of a frequency selective capacitive voltage divider.
  15. OperaHouse

    Lightning Protection For Off-Grid Long Distance Solar Array

    Any added inductance at the would help significantly at the charge controller with MOV array before that. A CORCOM like EMI filter would be suitable. Panel buss is generally not grounded. Midnight does not make any PWM controllers. It is being fed into a capacitor like any switch mode power supply
  16. OperaHouse

    12VDC Battery Power/Solar Power Backup/AC Invertor Portable Display: Grounding Problem

    I don't know if you are aware of it, but many inverters in that power range require a floating neutral. Grounding the neutral will either short out 1/2 of the H bridge output or cause the battery to be at a lethal potential. Stress this in your education. I remember the first inverter I...
  17. OperaHouse

    Feasibility and wisdom of measuring heater temperature via voltage-to-current ratio

    Erosion is an issue over time. A friend with a pipe fabricating shop had an argon/co2 mixer control. It had two cells with elements in a bridge. One measuring heat loss of the mixture and the other of the argon to determine the mix percentage. The bridge could no longer be balanced due to...
  18. OperaHouse

    Hi guys, I'm trying to transfer 1

    Of course it is going to ring. The coil should be driven with a full or half H bridge.
  19. OperaHouse

    Hi guys, I'm trying to transfer 1

    Why invent the wheel, I would use one of these as the power source http://www.ebay.com/itm/5V-12V-Low-Voltage-ZVS-Induction-Heating-Power-Supply-Module-Board-With-Coil-GW-/272775986770?hash=item3f82b73e52:g:LHwAAOSw0YlZdprh Transmission through air can be difficult with even at a small...
  20. OperaHouse

    How close tolerance does a run capacitor have to be?

    There is a discussion with a guy that says his air conditioner fan motor over heated and died because the manufacturer used a 7.5uF instead of the 5uF as stated on the motor. This motor has a run and a start capacitor. I think the cap just opened up or the bearings started to freeze. A friend...

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