ski_power Posted January 16, 2006 Share Posted January 16, 2006 http://www.uoguelph.ca/~antoon/circ/vps.htm I am planning to build a power supply as shown in the above page. Only there are 2 problems... 1. The power supply is rated at 1.5A, I want it to work at 5A or atleast 3A so what modifications should I make? 2. I don't have a voltmeter so I want to know if I can use some ICs to hook it up to a 7-segment LED for a digital readout? (Doesn't matter however complex) Link to comment Share on other sites More sharing options...
YT2095 Posted January 16, 2006 Share Posted January 16, 2006 1. you`ll need to UP the transformer to one that will supply that current, then your diode bridge will have to up graded too. Then you`ll need a power transistor directly off the + pre-regulated voltage with the output as marked up in that cct diag you liknked to, as the feed for the base of this power transistor. you`ll lose .7 of a volt, so your output will be .5 Volt min (that`s better IMO). I recomend either a TIP3055 or a 2N3055 as the output trans. 2. either Buy a volt meter or borrow one, they`re not expensive anymore! Link to comment Share on other sites More sharing options...
ski_power Posted January 16, 2006 Author Share Posted January 16, 2006 Ok, so you mean that i should replace the LM317 with the 2n3055? I wanted an LED readout coz i wanted to mount it in a metal case. So i still ask, any IC or circuit to electronically get the voltage reading, which can be displayed on the 7 segment? Link to comment Share on other sites More sharing options...
YT2095 Posted January 16, 2006 Share Posted January 16, 2006 no no, you Keep the 317 as the driver for the power trans, that`ll "tell it" how much voltage it can pass. as for the display, if I REALLY wanted to do it myself, I`de probably buy an A to D display driver and try to calibrate it to match the input voltage, perhaps the ICL7106 or 7107 maybe? Link to comment Share on other sites More sharing options...
YT2095 Posted January 16, 2006 Share Posted January 16, 2006 High Current Regulated Supply Original scheme edited by Bill Bowden, http://ourworld.compuserve.com/homepages/Bill_Bowden/ The high current regulator below uses an additional winding or a separate transformer to supply power for the LM317 regulator so that the pass transistors can operate closer to saturation and improve efficiency. For good efficiency the voltage at the collectors of the two parallel 2N3055 pass transistors should close to the output voltage. The LM317 requires a couple extra volts on the input side, plus the emitter/base drop of the 3055s, plus whatever is lost across the (0.1 ohm) equalizing resistors (1volt at 10 amps), so a separate transformer and rectifier/filter circuit is used that is a few volts higher than the output voltage. The LM317 will provide over 1 amp of current to drive the bases of the pass transistors and assumming a gain of 10 the combination should deliver 15 amps or more. The LM317 always operates with a voltage difference of 1.2 between the output terminal and adjustment terminal and requires a minimum load of 10mA, so a 75 ohm resistor was chosen which will draw (1.2/75 = 16mA). This same current flows through the emitter resistor of the 2N3904 which produces about a 1 volt drop across the 62 ohm resistor and 1.7 volts at the base. The output voltage is set with the voltage divider (1K/560) so that 1.7 volts is applied to the 3904 base when the output is 5 volts. For 13 volt operation, the 1K resistor could be adjusted to around 3.6K. The regulator has no output short circuit protection so the output probably should be fused. I`ve had to post this seperately as I tried to cut the cct diag also and am not sure if it`ll screw things up or not, anyway have a look here: http://www.qsl.net/yo5ofh/hobby%20circuits/power_sourse_circuits.htm at the "High Current Regulated supply" section, it`s the 9`th one down, and that`s basicly what I`m advising you to do/build. I have one that I designed myself right here next to me, using a Very similar cct, and it`s nearly 15 years old and still running perfectly! Link to comment Share on other sites More sharing options...
ski_power Posted January 16, 2006 Author Share Posted January 16, 2006 ok but in this supply there seems to be no way of varying the output voltage. And by the looks of it, it seems to require 2 transformers which ends up escalating costs... And I didn't quite understand where to put the 2n3055 in the ckt that i showed you... Link to comment Share on other sites More sharing options...
YT2095 Posted January 16, 2006 Share Posted January 16, 2006 *sigh* you`ve obviously NOT had a look at the link I gave to help you out read that 1`st and then see if you`d ask the same question. Link to comment Share on other sites More sharing options...
ski_power Posted January 17, 2006 Author Share Posted January 17, 2006 i saw the link, both of them... you're telling me to build the one with the "Bill Bowden" name right? yah, well i do think that it needs an additional winding, atleast thats what is shown in the schematic... So where doth ye transistor goeth? Link to comment Share on other sites More sharing options...
YT2095 Posted January 17, 2006 Share Posted January 17, 2006 You really surprise me! you say this: (Doesn't matter however complex) and then after looking at the cct diags, you ask me Where the Transistor goes!???? Link to comment Share on other sites More sharing options...
ski_power Posted January 18, 2006 Author Share Posted January 18, 2006 Well I told that for the voltmeter thing... You said this: "Then you`ll need a power transistor directly off the + pre-regulated voltage with the output as marked up in that cct diag you liknked to, as the feed for the base of this power transistor. you`ll lose .7 of a volt, so your output will be .5 Volt min (that`s better IMO). I recomend either a TIP3055 or a 2N3055 as the output trans." And I couldn't follow it, let's say that I've not completed my course in Engg. (Yeah and by the way I'm doing Engineering in mechanical, not electronics or electrical so maybe that's why i didn't follow what you said.) Don't transistors have 3 terminals anyway? So if the base is hooked up with the part before "in", where do the other 2 get connected... Link to comment Share on other sites More sharing options...
YT2095 Posted January 18, 2006 Share Posted January 18, 2006 well the bit that gets connected before the "In" is the Collector, to the Base goes the output of the 317, and the Emitter is the usable voltage that connects to the plugs on the outside of your PSU seriously use that cct diag, it`s well worth it! not only that, but we can use it a common frame of reference, and if you have any questions later, it`ll be easier for you to ask them and for me know that your prob is, the same will apply the other way around in my explaination. I can`t say fairer than that Link to comment Share on other sites More sharing options...
ski_power Posted January 19, 2006 Author Share Posted January 19, 2006 ok now i understood... Actually I also found the ckt diag that you gave to be a bit nicer than the one I saw...but the only thing I'm not confident is about the additional winding on the transformer because I think I'll have to make that myself and am pretty wary of doing that. If there was anyway the additional winding could be eliminated then I'd have no problem making it. OR If that type is readily available in the market then also I have no problem. So will I have to make the additional winding or will transformers be readily available that way? Link to comment Share on other sites More sharing options...
YT2095 Posted January 19, 2006 Share Posted January 19, 2006 I really wouldn`t even Try and do your own winding, you`de have to re-do the whole thing! as an extra winding will only up the voltage and not the current. you`re better off taking appart an old car batt charger for the transformer AND you`ll also get the matching bridge rectifier with it too infact if you`re Really crafty, you could even build the whole thing into the same case! Link to comment Share on other sites More sharing options...
ski_power Posted February 7, 2006 Author Share Posted February 7, 2006 Ok, I was like going cool with building the power supply. Like going out and buying the parts and all. Suddenly my friend has an idea. He asks our electronics professor about our circuit diagram, and that guy is like "OK, fine you've done all this, but you could use IC723 and eliminate all the other components a.k.a. capacitor, resistor etc,etc." We told him that it gives only 0.15A. Then he says that transistors could be used to obtain a current gain. The circuit diagram he gave us is like below My problem is will this work(I'm feeling doubtful, coz there's no regulation). He told us that the output of the transformer+bridge should be given as input. And secondly I am frankly getting bored of this entire drama, by my friends and the prof. AND I don't know what values to put for the resistances over there, and the transistor. We need 5A atleast man... Link to comment Share on other sites More sharing options...
lightwave Posted February 7, 2006 Share Posted February 7, 2006 Power supplies are expensive to home-build. Just buy one. They are only $100 for what you want. Components (if you build your own) will cost you that, at least. As a rough rule, for each watt of a power supply expect to pay retail about $1 to $2, depending on quality of build and accessories (like a built-in voltmeter). Link to comment Share on other sites More sharing options...
ski_power Posted February 7, 2006 Author Share Posted February 7, 2006 Holy Ninja Gaiden $100 is like waaaaay off my budget...I expected it to be done in like what max $15-20.... You know I am not funded under the Black Budget program, that's why. And I don't have enough money to spare (darn, especially after the Samsung 616T to SD 605 conversion) Since I need a 37V 10A power supply does that mean I'll pay 37*10=$370. YIKES!!!! No waaaay I can afford that man...if you read the above posts you'll find out it works out way cheaper on a DIY. Oh yeah, with $30 more I can get a premium bundle. Link to comment Share on other sites More sharing options...
Intesaruddin Posted March 30, 2010 Share Posted March 30, 2010 Hey, I have been designing somewhat similar circuit as above but i don't have the equipment to test whethe if its working or not. Do you have any suggestions how to test it with household items. Please hurry its urgent.http://http://www.scienceforums.net/forum/attachment.php?attachmentid=1186&d=1137431737 Link to comment Share on other sites More sharing options...
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