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I'm sure you've found the answer to your problem already but just in case anyone else out there is having a similar issue.
Just use a computer power supply the 12V(Yellow = +12V & Black is Ground) line will be fine, because though an ATX power supply can supply(1000W) 83A on the 12V rail its a Voltage constant supply so it will only supply the current necessary to operate your device. That's why you can plug a fan in at 40mA and a HDD that uses 3.5-4A on the same rail. Hope it helps! :)
connecting it to three-phase electricity will reduce the current.
i have machine of fabric raising. the machine manufacturer has installed the dc mechanical brake on Ac main motor. the winding coil fit in dc mechanical brake. it was burned. after repairing it has burned again and again. despite same dc card and voltage. now, coil repairer says for reducing the dc voltage. now coming out dc voltage 230. but, we required 170 volt dc. reply.
Obviously the manufacturer made a miscalculation somewhere, I would have the brake rectifier checked for correct voltage first if its the same one you say you are using ,if that checks out good, then the problem may be in the new part, using a coil with lower voltage wiring for proper resistance .an easy fix is to add something that draws 60 volts dc before the brake voltage ,a variac or an adjustable type pot. a voltage regulater ,60v transformer reducer added to the rectifier .. theres a few options.
so i have a pc power supply and i am going to use a pci cable to draw power from for a led lighting system and the led light system can only take up to 12 v at 2 a will that destroy the led light system or will it be fine? (also i cant open up the box that controls the light system to fix the blown fuse)
Use a 2amp fuse between the power supply and the LED lights,but the most important of all is before you try any power, LEDs use both series and parrallel if you connect the power wrong the LED will burn out easily ,if you run the LEDs in a string ,depending on what your doing and need more lights 110 v ac in series with 6 amp fuse will work too.so for example if LED is each 4 volts to a max of 78-82 volts a string 15 leds on 2 strings each 30 total in series. try this neat trick 2 AA batteries on 1 led make sure pos and neg are correct or could burn it out. LED lasted continuosly on for over a month.
If your trying to use a battery charger as a 12volt power supply ,A 3 stage floating charger should work with a bridge rectifier there are amp settings already on the charger and it should not damage your NST .If your using just the transformer out of an old battery charger then i would recommend a Magnetic Amplifier or a Ferroresonant Magnetic Coupler both use magnetic shunts to adjust the voltage/current on primmary or secondarys of the transformer ,and can be easily built, but should add a heat sink and fan if using continous..third use a 110v to 12vDC inverter. i dont recommend a computer power supply it wont produce the current needed to run a NST
There are 2 ways of doing it and both are heat producing, either way the excess energy is lost out.
1. add a small value resistor in parallel to your power source and it can be calculated as below. Plus an additional zener for over voltage protection.
say your source current rating is Ir and your resistor draws I1 and your sink or target is Is (eye sink).
Now Ir = I1 + Is, imply I1 = Ir - Is (i.e. Rating current - Sink/target current)
Since the parallel resistor maintains the potential needed by your device we calculate the resistance value = 12volts/ I1 (i.e. standard 12 volts divide by Current through resistor). It will be a high wattage wire coiled resistor in most likely case and would require cooling so that you dont fry anything unintentionally.
2. using an inductor to save up energy build and a fast switching RC circuit which discharges the inductor pretty quick before reaching the specified charge. Need to do the calculation as i have become rusty.
3. use a high capacity regulator chip like 78H12A. Need to check if it suffices for 12V and 5Amps output which it gives out.
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Posted:Sep 30, 2010
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