Guest liquibyte

0-30V 0-3A Latest Data

45 posts in this topic

Post and followup post by tubefans007 of his version of the project.  He only made these two posts and didn't include any information about if this worked or not so YMMV on this one.

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Finally, my post with the Eagle .sch and .brd, full gerbers, and parts list for Digikey in a zip file.  I'm also including many of the pics I took as I was building that were posted both before and after this post.  I'm still not completely done and may add more pics later.  One thing I have changed is the third transformer for the auxiliary circuitry for the temperature sensor and fans and the displays (I wanted a better transformer than the Radio Shack special I had on hand).  Archive attached.

30V.zip

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mato100 and navidmomeni like this

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Continued

Edit: I've added a Digikey BOM exported as a spreadsheet as an attachment if you need it.  If you just want to order the parts I have listed, just register or log in to your Digikey account and go to this link and you should be able to checkout from there by clicking the "Create Cart" button at the bottom of the page.

I have not included the mounting kits for the TO-3 transistors, any heat sinks, a case etc.  I figure these things are more of a personal preference and can be had much cheaper elsewhere anyway.  What's on it are all the parts that appear on the actual schematic plus the transformer.  These are the parts I ordered for the final version I built.

As of 08/30/14 this BOM totals $102.32 and prices may change over time.  You can obviously omit the transformer if you have one already or if you want to use another one such as a toroid.  The one I have on the BOM is a large E-I core because it's basically the cheapest one they have that's up to spec.

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0-30V_0-3A_BOM.zip

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I thought a might as well add my own efforts here. I built my own version of the PSU. ( 0-25v 0-3A). As I had a transformer to hand I tweeked the circuit to suit. I replaced the voltage reference circuit as I found the existing one was not that stable! This one is stable over a wide voltage and temperature range. After a lot of testing I changed the ground reference (pin 4) of the voltage control IC to AFTER the current sense resistor. This made a BIG difference to the regulation performance (0.02%). Hope this helps.
Eric

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Hi all

Ok, this is my end result. Built and tested and works quite well.

I started with the version posted at the start of this thread. However I had a couple of problems with the current limiter. I didn't have much success with the current limiter clamping the input of U2 - sometimes it would not go right down to 0V, sometimes it would go just below. Just below was a big problem for me - U2 would start to oscillate, with bad consequences for anything connected to the output of the Q4... It would then drive the output high just when I wanted the current limit to become active :'( I should add that I did not use TL2141 or MC34071s, this might be the root of my problem. I fixed this issue with a small change to circuit layout rather than going to expensive opamps.

My mods (compared to the circuit posted on start of this thread):

* current limit - I removed D9. To replace this, I added another BC548 - the base is driven by the current flowing through the current limit LED. The collector of this BC548 clamps the output of U2 (exactly like the existing BC548 driven by the negative rail). This arrangement means we don't care how close to its supply voltage the output of U3 can go. It avoids the possibility of driving the input of U2 out of spec. Clamping the output of U2 is much more like how the integrated voltage regulators work. It seems better to my mind, to keep U2 out of the loop when current limit is active. [Edit: note that U2 will need a small heatsink with this arrangement]

* some rearrangement of the opamp power connections, for all three opamps... U1 & U3 are run via 15V zener diodes, to give a supply of approx 30V. That allows almost any cheap opamp to be used for U1 & U3 (741s or TL071 etc). U2 is connected to unregulated 44V and to the output side of the 0R47. 

* I used a MC33171 opamp for U2. It is high voltage, but much cheaper (they are £0.60 in UK) than TL2141 or MC34071 (both are £5 here). It is a low power IC by comparison.

* 0-30V 4A transformer.

* 2 x 6800uF smoothing caps.a big thanks to the contributors on this thread for their efforts, my project was greatly speeded up by borrowing a lot of their ideas

 

Edit:

* I also changed the 0R47 to 0R2, as the 0R47 generated too much heat at 3A for my liking. This also means R18 changes to 330K. These two values are not shown on the schematic here.

 

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Hi all, I'm new here and I am also building this project, I will consider the schematic posted by Weightlover

8 hours ago, weightlover said:

Do you have the latest project PCB ?  To this schematic:0-30V_Schematic_Rev7_Aug_2014.gif

I also need. someone has the PCB and the top with components?

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hello friends,

 

I have made power supply as shown this article 30V3A, my problem is, i want  set current  only 200mA limit, and voltage to 30V, i had tried a lots but each time when i connect load, at 150mA of current voltagedrop becomes 15V, is there any problem in my circuit due to this voltage drop appear. basically it should work like upto 200mA it must give 30V after that voltage goes down but before this lime voltage is going down, I m newer in this field, can anybudy sortout my problem.

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To use your transformer then many resistor values will need to be re-calculated and changed. The 16.6VAC will have a peak voltage of only 23.5V. The improved circuit is designed to use a 28VAC/4.3A or 30VAC/4A transformer. If you re-design the circuit then with your transformer its maximum regulated output will be about 16.5VDC at about 1.5A. 

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On 4.1.2017. at 3:50 AM, audioguru said:

To use your transformer then many resistor values will need to be re-calculated and changed. The 16.6VAC will have a peak voltage of only 23.5V. The improved circuit is designed to use a 28VAC/4.3A or 30VAC/4A transformer. If you re-design the circuit then with your transformer its maximum regulated output will be about 16.5VDC at about 1.5A. 

Thank you very much!

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Hi friends 

I need to build this project for me and i need to guide me for the best schematic for this project and PCB with components. Thanks 

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Hi all,

Finally after some months have gone by, my build of the Power Supply is done.

I have used liquibyte schematic Rev. 8 and had made the cirquit board according to the Gerber files in file 30V.zip from his post above.

I have plenty of boards leftover if someone has a need for it. There was only one mistake liquibyte made which have outlined in one of the pictures uploaded here.

I was fortunate enough to get a big case with a Toroid transformer from the scrapyard. Also many parts are recycled from various sources.

Regards, William

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