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General Category => Your projects => Topic started by: pantelis on April 07, 2012, 16:03:48 PM

Title: Power supply 0-30V 5A step by step creating
Post by: pantelis on April 07, 2012, 16:03:48 PM
Hello guys, I would like to present a power supply I made from the begging. I had imagine this case and exactly it appears here and I make my vision true!
Lets start
It’s a power supply 0-30 volts and 0-5 amber constantly ,we can increase the current up to 10 amber adding fans to the output tranzistors 2n3055.
Here is the circuit, as you can see we can adjust the voltage and the current too.
it consist of lm723 as current  and voltage regulator and some components  , With TR2 we adjust the MAXIMUM voltage so that don't break out 30 volts, P adjust the voltage and TR2 adjust the current
The transformer has two windings one is 18V ac and the other one is 36 volts
I found the diagram at the net, if i have to show the link let me know
here is pcb
http://www.2shared.com/document/4B94P_d6/0-30volts_pcb.html (http://www.2shared.com/document/4B94P_d6/0-30volts_pcb.html)
I have made a heatshink for the output power transistor 2n3055



I took a box and I place two hinge to the upper case and another two to the front case so that I can be opened and place the pcbs without problems


and now I place the heatshinks with transistors to the back of the case


I bought two meters one for amber one for volts for about 5 euro each

here I ‘ve place a filter from a power supply from computer ,a switch and a fuse

here is the project with to potentiometer the right we can adjust the volts and the left we can adjust the amper
the frond face, I have open a square hole at the center because I want to place a digital amber meter to measure amber 0-1000 miliamber, I ‘ll explain afterwards

at this point I decide I don’t like the colour of the box, so I paint it ,but the colour became dark enough !! it looks like a very old radio!! Lol but it continuous to be a power supply
I found two knobs in my drawer too, but unfortunately its not the same


Now lets continue with the pcd


I have use two electrolytic capacitors 4700mF 71 volt each but not new as you can see and not 4x2200mF 40 volt suggested from the circuit because I think 40 volts is not enough
I place all the stuff inside and I made the connections, the transformer is 2x18 volts ac taken from an old television


I place a bridge rectifier KBPC  bought from ebay 50A 1000V

you can have a closer look at this point watching the video
http://www.youtube.com/watch?v=Ezz8kpLl3hU&feature=youtu.be (http://www.youtube.com/watch?v=Ezz8kpLl3hU&feature=youtu.be)
Amber meter
Here is the digital voltmeter







because the ic that use the voltmeter ICL 7107 need symmetrical sypply +/-5 volt and I didn’t want to use symmetrical supply I made this circuit with 555 (IC2) timer so that to use +5 volt supply
the circuit with 555 timer  is here
now we will convert the voltmeter to ampermeter changing the components as it look likes , at pins 30 – 31




I place display down from the pcb because I had problem with the space
I use an old charger from mobile phone to supply the amper meter , it is a switching stabilizes supply 5 volt ,it is very small and reliable, best solution



as you can see at the following video, ammeter has a good responsibility, but i don't know why its not stable, its moving +/-0-3 mA .Maybe the problem is the oscillator for 7107 .P1 trimmer is better to be used a multiturn trimmer so that to adjust it, with more accuracy
http://www.youtube.com/watch?v=arRgoOdlssI&feature=youtu.be (http://www.youtube.com/watch?v=arRgoOdlssI&feature=youtu.be)

Now, i should place a switch so that to change the windings of the transformer, 18 vots or 36 volts, i found the proper  one




My vision has come true! Its finished


i found a cover for display



Look at this video, its a  testing with a lamp 6V 0.5A, there is very good accuracy compering it with a multimeter

http://www.youtube.com/watch?v=DJEHOD__3sk&feature=youtu.be (http://www.youtube.com/watch?v=DJEHOD__3sk&feature=youtu.be)

---------------------------Cheers from GREECE!!-----------------------------------

Title: Re: Power supply 0-30V 5A step by step creating
Post by: kam on April 08, 2012, 15:05:31 PM
Excellent presentation, thanks for taking part with this complete documentation.  8)

but i cannot find the circuit for the ammeter.  did you have a link to somewhere?  :-\
Title: Re: Power supply 0-30V 5A step by step creating
Post by: pantelis on April 08, 2012, 15:23:22 PM
tnxs, you are right i forgot it, now its ok !!
Title: Re: Power supply 0-30V 5A step by step creating
Post by: diyguy on June 15, 2013, 17:23:45 PM
Wow that's impressive nice  8).