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OT- high voltage module

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  • OT- high voltage module

    Probably a good question for Evan- I have some modules removed from a photocopier. These are labeled Galileo GHB-3, and there are terminals labeled -5.5 kv, ground, and in. I assumed they are high voltage generators, but I'm not sure how to drive them to get any high voltage out. I have tried feeding 110ac to ground and in, but all I can read on my meter is about 40 volts output. A DC voltage input doesn't give any output, and there's no current drawn from the supply at all. Any idea what it takes to make these work?

    There are three on one circuit board, one is labeled -6.5kv CH, another is -5.5kv TR, the last one is +5.5kv CL. That covers the total of the markings on them. Any of this make sense to anyone?

    Several months ago I asked about making an aluminum foil capacitor. Today I finally got around to winding up the two rolls of foil and two rolls of parchment paper. I ended up with 1.5 uf- a bit more if I squeeze it tightly. Now I want to give it the voltage test- I was hoping to use one of these modules for a test voltage.

    An interesting find- though a check with the 20 meg ohm range shows no leakage, the charge will drain off fairly rapidly. A 12v charge will decay to less than a volt in about one minute. So far I've only applied 60 volts to it, which is far less than it should be capable of taking.
    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-

  • #2
    Usually the high voltage supplies in a copier run on something like 24v dc. If you applied 110v AC to it you may have fried it. Got a pic?


    • #3
      5kv may puncture though paper, I wouldn't push it over 1kv without using plastic or some kinda oil imprenated paper.

      Vchange per second = I / Farads
      So all thats needed to drain 12v in 1 minute at 1uf is 0.000012amps
      or about 1 mohm~
      Sure you didn't mean 1nF?

      Also, 20Mohm ranges often need several seconds to 'stablise', did you connect it with clipleads and give it some time? Maybe the cap had a charge and that was throwing off the meter? (Short out the cap)
      Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.


      • #4
        Paper is about 200v per mil. So to hold off 6kv you will need .030 paper, minimum. Thats pretty thick.


        • #5
          Here's a pic

          I don't intend to feed the full voltage to the cap- I figured I'd crank it up to about 300 volts for a start, then go up from there. The paper is .002 thick, apparently silicon coated. I have also made up a small test capacitor, which is the one I'll test first.
          Last edited by darryl; 04-07-2013, 06:35 AM.
          I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


          • #6
            From my time working at Xerox as a service tech on their copiers, those appear to be "corotron" supplies, which feed HV to thin little hair like wires that charge the copiers drum. Most units would feed these things with HF signals (60hz line frequency is useless). They are basically the same principle as a TV flyback transformer, where they generate large voltages, but to keep the size down they are driven by HF pulses (in the Khz range.)


            • #7
              Those are voltage multipliers. They require higher voltage in than what you are giving them. They should work fine at lines frequency though. I would find something else to mess with.


              • #8
                I figured they would be voltage multipliers since there's no conductivity at all on the input. After feeding the lower voltage dc and getting no results, I tried ac- ramping it up with a variac. The output voltage did follow the input rise, but the level was much lower. It makes sense then that it's looking for a much higher frequency on the input- perhaps coming from a switching power supply which I think is what this copier had. Probably not worth trying to get these operating- I can get high voltages a lot easier than messing with this.
                I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                • #9
                  Google "tesla coil poy caps" for far more information than you ever wanted about home made high voltage caps. You want either mylar for DC or poly for high frequency (RF and up). It is a much better insulator and much higher dielectric than paper. Most tesla coil builders use many layers of 6 mil poly to withstand 15 KV. Many have gone to arrays of 1600 volt poly caps wired in series parallel. Much less mess and much more reliable without that much more cost. You can immerse the home made cap in mineral oil to improve things a bit. A vacuum pump will help get out the air bubbles. A big array of caps dumping into a coil of copper tube can actually shrink a coin (and make it thicker). Be careful when playing with these voltages and amperages!



                  • #10
                    Long time ago I built a tesla coil. I made my own cap for the primary, and made it adjustable. I had a slightly curved plexiglass top and bottom, sandwiching layers of aluminum foil and mylar sheets. One edge of the assembly was clamped and fixed, while the opposite edge had a threaded fastener. When that was turned, the curved plexiglass would squeeze down on the stack as the curve slowly straightened out. Tightened all the way, the curve in the upper and lower plates flattened out, and the capacity was at a maximum. Worked well.

                    I find coin shrinking interesting, but have never done it. My uses for high amperage would be more useful, such as for spot welding. High voltages are fun also, and I am aware of the safety aspects. This capacitor project is just for fun and doesn't have a use at present that I can see. The materials came up cheaply, so it was time for me to just do it. Get it out of my system, as it were.
                    I seldom do anything within the scope of logical reason and calculated cost/benefit, etc- I'm following my passion-


                    • #11
                      From my time working at Xerox as a service tech on their copiers, ...
                      Another victim... I worked for them for 23 years, since '75 to '98. I have been to TO twice for a total of about 5 weeks for training. Many other courses all over the continent since I worked on around 50 products by the time I left. Everything from engineering to systems to copiers etc. Yep, those are corona supplies but not likely transformer type, unless they are heavy. Two of them will be DC out and one will be AC. It probably does have a small flyback coil in the AC supply. CH stands for CHarge, TR is TRansfer and CL is Cleaning. The CL will be AC with about a 1000 volt DC bias as it is to neutralize the remaining transfer charge. Most just run on AC line with output of 5 to 20 milliamps but that is not assured. I doubt any of those put out 20 ma as that would be around 50 watts. The newer machines use organic photoreceptors that are easier to charge with a lot less leakage so they need much less current.
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