MP Posted January 13, 2004 Report Share Posted January 13, 2004 If the link does not work, just go to www.allelectronics.com and use the search box. Enter pm-200 for the search.MP Quote Link to comment Share on other sites More sharing options...
MP Posted January 13, 2004 Report Share Posted January 13, 2004 In reply to the question asked by Derfly, you can connect the potentiometers in series. More importantly, for the fine adjustment, you will want to use a 10 turn or a 15 turn or even possibly a 20 turn pot to give you the accuracy you want to achieve. This should be on the smaller value pot as you want maximum number of turns for smallest voltage change.Hope that helps a little.MP Quote Link to comment Share on other sites More sharing options...
kurt Posted January 15, 2004 Report Share Posted January 15, 2004 hiu seems to be quite in to the electronics fieldkurt Quote Link to comment Share on other sites More sharing options...
DerFly Posted January 16, 2004 Report Share Posted January 16, 2004 MP Thanks,I undestand wiring in series but the variable resistors in this project have three connections. To wire two variable reistors in series, how is this done. Could you possible supply a diagram?Many thanks,DerFly Quote Link to comment Share on other sites More sharing options...
MP Posted January 17, 2004 Report Share Posted January 17, 2004 Yes, here is a diagram. Two ways to do it. Both are the same.MPpotentiometer.pdf Quote Link to comment Share on other sites More sharing options...
mixos Posted January 17, 2004 Report Share Posted January 17, 2004 I attach it here also for fast view... HaddyS 1 Quote Link to comment Share on other sites More sharing options...
Guest KIRKCHABO Posted January 26, 2004 Report Share Posted January 26, 2004 Help!I am new to the electronic world and i need some clarification on the resistors in this project.R1=2.2Kohm 1 watt (ok)R3=220ohm 1/4watt (ok)R4=4,7Kohm 1/4 watt (?)R7=0,47Ohm 1/4 watt (?)R9=2,2Kohm 1/4 watt (?)R14=1,5Kohm 1/4 watt (?)I kown this probibly sounds dumb but I don't get this?Thanks In advance Quote Link to comment Share on other sites More sharing options...
MP Posted January 26, 2004 Report Share Posted January 26, 2004 Think of the commas as periods or the periods as commas. These are used differently in different continents. It means the same.MP HaddyS 1 Quote Link to comment Share on other sites More sharing options...
Guest KIRKCHABO Posted January 26, 2004 Report Share Posted January 26, 2004 thanks mphelp I checked all solder joints and componets but when i start it upit seems ok till i put a load or even without a load (meter) when i turn up the current dial even a little bit the led starts flashing and i go into overload.lost in space Quote Link to comment Share on other sites More sharing options...
juanpmoron Posted February 9, 2004 Report Share Posted February 9, 2004 I have a problem with the power supply: when the output shortcircuiting, the Q2 (2N2219) burn up! :PWho can I help me? Quote Link to comment Share on other sites More sharing options...
ante Posted February 10, 2004 Report Share Posted February 10, 2004 Check R16. ::) Quote Link to comment Share on other sites More sharing options...
juanpmoron Posted February 10, 2004 Report Share Posted February 10, 2004 Check R16. ::)R16 is 1K and is OK ??? HaddyS 1 Quote Link to comment Share on other sites More sharing options...
MP Posted February 10, 2004 Report Share Posted February 10, 2004 All the components around the IC are for the current limiting circuit. You should check all of these parts for correct values and orientation.Did you leave anything out that you felt was not needed? Even the LED is part of the current limiting circuitry.MP Quote Link to comment Share on other sites More sharing options...
FireFly Posted February 11, 2004 Report Share Posted February 11, 2004 I have a heat sink from an old stereo receiver that I think is substantial enough for this project. The project page states:"...use the mica insulator between the transistor body and the heatsink..."I will be able to re-use the screws and plastic hole inserts but there was a piece of clear plastic between the sink and transistor that is too small. What should I use? Is there something around the house or hardware store I can use or do I have to hope :-\ my local electonics store guys will know what I am talking about?Also:"Use a little amount of Heat Transfer Compound between the transistor and the heatsink..."Would that be between the transistor and mica insulator, between the mica insulator and sink, or a layer on each side of the mica insulator?(Curiously, the old, built-like-a-tank receiver didn't use any goo; just the piece of clear plastic between the sink and transistor.)On another note, I received the 2N3055A and numerous other "samples" from ON Semi http://www.onsemi.com They charge $15 US for shipping and handling but I felt it is well worth it if you order enough pieces or you are having trouble finding stuff locally.Thanks. Quote Link to comment Share on other sites More sharing options...
mixos Posted February 11, 2004 Report Share Posted February 11, 2004 Hello FireFly You can buy a plastic insulator that is made exactly for the dimentions of TO-3 package transistor and has good heat transfer characteristics. The clear plastic you have is old type. You can also find other kind of matterials that are like rubber . Almost all electronics parts stores has it. I attach you also an image that saws how to use it.Regarding the "Heat Transfer Compound" you can put it both sides of the mica isulator for better performance. Quote Link to comment Share on other sites More sharing options...
Shahriar Posted April 3, 2004 Report Share Posted April 3, 2004 Hi,I want to use the pcb of the 30V power supply but when i print it, it Becomes too much big, Can anybody tell me how i can fit it in actual size (12.5cm x 8.7cm)your help is appreciated in advance Quote Link to comment Share on other sites More sharing options...
mixos Posted April 3, 2004 Report Share Posted April 3, 2004 The best way to print it out correctly is to make some test prints to find the correct ratio. Take a part with fixed dimensions (like an IC) and try to fit it on the print out paper. Then change accordingly the ratio (resize scale) to achieve the correct dimensions. It is better to use a program that allows you to change the percentage (%) of the print out. Quote Link to comment Share on other sites More sharing options...
Shahriar Posted April 3, 2004 Report Share Posted April 3, 2004 Thanks a lot for your help... :) Quote Link to comment Share on other sites More sharing options...
Kevin Weddle Posted April 5, 2004 Report Share Posted April 5, 2004 This power supply looks a little simple. I would design my own and forget about the opamp, most likely. With so many possibilities, you have to wonder what the ideal operation is. This is the circuit I use presently, but I need a better one. Quote Link to comment Share on other sites More sharing options...
ante Posted April 5, 2004 Report Share Posted April 5, 2004 Hi mastrila,If C7 gets hot you probably got oscillation. The only way C7 can get hot is if it Quote Link to comment Share on other sites More sharing options...
Ani Posted April 9, 2004 Report Share Posted April 9, 2004 Hi everybody,Can I place LF351 in place of TL081 in this project. I checked the datasheet, both of them are almost similar.Regards,Ani Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 10, 2004 Report Share Posted April 10, 2004 Do not use a 2N2222 instead of a 2N2219 for Q2 since it must dissipate up to 5W and therefore is shown with a heatsink.The 2N2219 has a larger metal case and is designed for use with a heatsink. The 2N2222 has a small plastic case and cannot dissipate more than about 1/3W. With 5W in a 2N2222 it will smoke then burn.Although the two transistors have the same voltage and current ratings, the little 2N2222 is designed to SWITCH current (when switched-on it has very little voltage across it and therefore low power). Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 10, 2004 Report Share Posted April 10, 2004 Hello Tom and others,You CANNOT put stabilized power supplies in parallel since you cannot ensure that they have EXACTLY the same output voltage. The supply with the slightly higher voltage will carry the whole load while the lower voltage one(s) will tell its regulator that the voltage is high enough or is too high and therefore to shut-down.Although you CAN isolate parallelled supplies with a series resistor from each one's output to the load, so that the supply with the slightly higher voltage carries enough current to allow its voltage at the output of its series resistor to drop to the level of the slightly lower voltage one(s) so that this one (these ones) carry the remaining current. But those series resistors ruin the voltage stabilization since the output voltage will fluctuate with load current changes. Quote Link to comment Share on other sites More sharing options...
MP Posted April 10, 2004 Report Share Posted April 10, 2004 audioguru, what are you referring to in this post? Multiple regulators in parallel? Complete supplies in parallel? Which post are you replying to?MP Quote Link to comment Share on other sites More sharing options...
audioguru Posted April 11, 2004 Report Share Posted April 11, 2004 MP, I was replying to Tom in his reply #9 in this post where he asked if he could parallel 2 of these Stabilized Power Supplies to get more output current.My reply refers to paralleling these supplies, any other regulated supplies and IC regulators in general. Quote Link to comment Share on other sites More sharing options...
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