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    Open hardware solar power generator for developing countries

    One resource for information on systems installed in isolated areas with basic system data, but not detailed schematics, is Home Power Magazine. Lots of discussion and examples of system design and capacity calculation. They offer CDs of multiple years of back issues on each.  I certainly do...
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    new project using tlp741g (photo scr)

    Have you looked at thedata sheet for the tlp741g?   http://www.toshiba.com/taec/components2/Datasheet_Sync//209/4322.pdf It is a low-current (150ma), moderately high voltage (400v) SCR with a photo sensitive gate that can be triggered by light from the embedded LED with LED forward current up...
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    'Soft-starting' a DC motor, is this the solution??

    PWM is not the only way to soft start a DC motor but it is certainly the most efficient way in most cases. If you just want to soft start the motor and have no servo control requirements, I would think any basic PWM generating IC driven by a ramp and driving a single IGBT or MOSFET of...
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    Using electro-plating rectifier as a low-voltage high-current power supply

    Sorry to make such an obvious suggestion, but have you asked the manufacturer of the power supply how his unit will handle your load and what precautions to take? Looks OK to me but then, it's not my $12K. awright
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    hv transformer wiring

    While it is true that a neon sign transformer is current limited by design, do NOT assume that you can be casual about dealing with the high voltage.  It only takes 10-20 ma through the heart to throw it into fibrulation with possibly lethal results and I believe that neon signs operate on...
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    BTY79 and C106D Thyristor.

    Why is this question coming up again?  Did you post the same question on a different forum? The answer is the same as before.  There is nothing at all critical about the SCRs used in this circuit.  Any voltage rating will do because you can't find an SCR with too low a voltage rating for a full...
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    reading 30kV dc in a 30 V dc voltmeter

    Using a commercial HV probe like the Fluke suggested by Ken is definitely the best way to go.  However, such an accessory must be used with a DVM having the proper input resistance.  This is automatically taken care of if you use the probe with most Fluke DVMs.  It will definitely NOT work with...
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    Quick Heaters

    I wouldn't try to switch the secondary current.  Switch the primary on and off, as is done in a soldering gun.  You will pay dearly for a relay that will work in your secondary circuit.  Also, you will be adding contact resistance to the secondary loop where it will affect performance.  Remember...
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    POWER OFF ON with delay

    Google "Watchdog Timers."  TI, Maxim, Analog Devices, and many other chip makers make devices with various levels of complexity and sophistication to restart a system if voltage levels drop below some threshold or if the watchdog input senses an absence of normal system activity or if it...
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    Need to convert a music synthesizer from 110V to 230V.Voltage and fuse questions

    Your machine will run fine on the original fuses but you will lose protection in the event of a failure that would have blown the recommended fuses.  I strongly recommend installing the recommended fuses but if it will take some time to obtain them from the states, I would go ahead and use the...
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    wireless electric billing... is it possible?

    That's exactly what the new "Smart Meters" that the utilities are at this moment investing multi-millions installing do.  They are queried periodically and respond with the electrical usage information.  I do not know what technology they use for the link to the utility.  I also do not know how...
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    DC conversion for AC welder using a Bridge Rectifier & Capacitor or Inductor

    What makes you think that you must smooth out the ripple on the full-wave rectified waveform coming out of the rectifier bridge for welding?  Why would a smooth DC voltage/current work better than the raw rectified wave?  The heating value of the arc will not be significantly affected. Now...
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    Help me..problem to triggered relay

    Are you still there and still interested, 89Panadol? Most likely your relay has a coil with too low a resistance.  What type of relay is it and what is its coil resistance?  How much current does the coil draw if connected directly from your 12 volt supply to ground?  How does that compare with...
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    Technical help on building a low wattage heater.

    It would be more useful for you to tell us what you are trying to heat.  It is straightforward to calculate the POWER dissipated in a given length of a given type of wire at a given voltage.  Except for very standardized conditions and media, calculating the TEMPERATURE attained (In the wire...
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    Cooling a resistor load at 6 to 10kW

    stube40, what ever happened with your high power test load? awright
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    Cooling a resistor load at 6 to 10kW

    I concur with Alex's recommendation to avoid oil as a coolant on the basis of mess and cost.  Disposal of a tank of water is SO much cheaper and easier than a tank of oil.  Is this a long-term or a single-shot project?  Oil is used in transformers for reasons other than thermal efficiency, like...
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    Testing a 3 phase transformer

    You don't say anytiing about the size or ratings of the transformer but if you are hoping to use it as part of a welder it must be fairly large.  That implies a very low DC resistance because the DC resistance is simply that of the (heavy) wire in the winding.  In the absence of very...
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    submerged electronic..need help!

    As Hero999 says, cleaning with water is acceptable.  I first remove or protect any components that could be damaged by water, spray with a detergent solution, scrub with a toothbrush, rinse very well, then finally rinse with distilled water (available by the gallon at your local supermarket -...
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    thermo electronics

    Hero999, the joule is a unit of energy and the watt is a rate of energy flow, i.e., power.  One watt is equal to a rate of energy flow of one joule per second, as jt stated.  A watt is a watt is a watt in any consistent system of units, be they thermal, mechanical, or electrical.  Mathmatically...
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    220 to 110 V convertor advice

    I agree with Alex.  Not much to go on from your sketch.  Detailed photos AND a description of the device you are trying to repair would be very helpful. awright
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