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    0-30 Vdc Stabilized Power Supply

    Hello everybody I finished building my modified project maybe a year ago and promised back then to post some pictures as soon as i could get my hands on a digicam :) Well, here they are: Outside: The output can be shortened and switched off by two flick switches. This allows adjusting of...
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    0-30 Vdc Stabilized Power Supply

    The stupid thing will only show the current flowing trough it, but this hasn't always to be the current flowing trough the load :D In plain: You can connect a switch across the output terminals of the project and produce a shortcut by pushing it. Then you can adjust the current limit, flick the...
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    0-30 Vdc Stabilized Power Supply

    Did you make sure that every diode in the negative 5,6V supply is soldered in the right way round?
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    0-30 Vdc Stabilized Power Supply

    I think the terminals of D7 are connected in the wrong way. Just try to rotate the thing by 180
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    0-30 Vdc Stabilized Power Supply

    I put an additional 8.5VAC winding on my toroidal core transformer in order to increase the voltage so 30VDC could be delivered. Because the heat generated at worst case, which is a shorted output and full current, was far to heavy to dissipate with my little heat sink, the additional winding is...
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    0-30 Vdc Stabilized Power Supply

    Well, I used a heatsink and thermal grease. But I soon discovered that the heat can't get away only by thermal convection, so now there's a 92mm @8V fan on it. I'm positive that this should work quite reliable. Maybe I can post some fotos of the case I made for it as soon as it's done. @MP...
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    0-30 Vdc Stabilized Power Supply

    I think I should add something here... I made a few tests by myself while building my own (modified) project. I had to use a 29VAC trafo and a 10.000µF cap in order to get 30V/3Amp with (nearly) no ripple. There is no way that the original 24V trafo and the 3300 uF cap could have been...
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    Convert 0-30V 3A PSU to 5A or more

    Hi anyone I've got a suggestion to make the project cheaper and perhaps less temperature-dependent. TI's TL431 makes a temperature-compensated Z-Diode, which output voltage can be adjusted by two (temperature-stable) resitors. That can replace the expensive U1. There is a problem, though...
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    0-30 Vdc Stabilized Power Supply

    Using a fan blowing over the heatsink could be a solution, too, if you don't want to buy a new heat sink. You need a very big heat sink to get 123W away without active cooling and even than the thing will get hot as hell. That is not good for the caps and will spoil the accuracy of voltage and...
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    0-30 Vdc Stabilized Power Supply

    Well... my datasheet (SGS-Thomson) says something different: When the reg is lying before you with its legs towards you and the writing on top, it goes from left to right: GND, Input, Output. A 78xx, on the other hand, has Input, GND, Output. Annother chip manufactory says the same...
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    0-30 Vdc Stabilized Power Supply

    Hi Divljo, The 7805/7905 circuit seems strange to me... You know their pinout is different from each other? Pin 2 is ground with 78xx, but input with 79xx. Why are they connected with each other? Plus, filter caps are missing near those voltage regulators. Maybe they will get unstable under load.
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    0-30 Vdc Stabilized Power Supply

    Hm... Well, I didn't measure that 3VAC drop. But 4,24A is still much smaller than the rated 5,83A. But annother thing puzzles me: The trafo is rated for sec. 20.5V, 5,83A and 140W. 20,5V times 5,83A equals only 119,52W. Something doesn't fit there ??? 23,5V times 5,83A would equal nearly...
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    0-30 Vdc Stabilized Power Supply

    Ehm? Maybe there's a bit of misunderstanding... With no load, I have 23,5V. When 5,83A are drawn, the voltage would go down to 20,5V. Never tried that, but it is printed to the trafo and sounds plausible. I don't draw that much current, therefore the voltage won't go down that far.
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    0-30 Vdc Stabilized Power Supply

    Hi audioguru, Well, before that, I used 4 paralleled resistors of 39Ohm/2Watt. They became glowing red after 5 seconds, and smelly, too :D A burning 2N3055 doesn't smell that well, too, I've found out ::) The next problem with these resistors is their temperature drift meaning the current will...
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    0-30 Vdc Stabilized Power Supply

    Hi audioguru, The trafo is rated for 140W and seems to stay quite cool @30V/3A output. But I could test that high load only half a minute before my load resistors (12 paralleled 120Ohm/approx.5W) are getting bloody hot. The secondary winding will have its 20.5VAC when loaded with the rated...
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    0-30 Vdc Stabilized Power Supply

    Hi audioguru, The original winding has only 20.5V rated voltage, but gives 23.5V when unloaded. Right now I've finished some further tests with the additional voltage being smaller. 8VAC unloaded works nearly fine, with little ripple at 30V/3A. If the voltage gets smaller, the ripple...
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    0-30 Vdc Stabilized Power Supply

    I' ve just soldered it together and made a few measurements. It seems to be quite fine :) At 30V and 3A Output I couldn't measure any ripple at all. My 10.000µF cap does its job well ;). Because C1 is off the board and connected with wires to it, I soldered a 220µF on the...
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    Board Design Programs?

    I use Target 3001. You can get a free demo at http://ibfriedrich.de. The demo can handle up to 100 pins (enough for small projects). A 50€ Version gives you 400 pins.
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    lm7812 problem

    Hi jpp, Did you probably forget the filter caps of 100n and 330n near the regulator?
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    Piggy-backed PC power supplies?

    Well... What did mean by "higher wattage"? Do you want to have more current or more voltage? More voltage can be done quite easily by just connecting them in series, but I assume that's not what you wanted... More Current, on the other hand, is very difficult to achieve because you have to...
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