0-30V Stabilized Power Supply

[singonn2]

hi everyone , now i doing new 5A power supply project  using schematics and part list provide by redwire in first page .

now i meet a problem , the LED is light while i switch on power same as noworries , i still using 24VAC 3A transformer for a test before get a new 30VAC 5A transformer.

When i using TLE2141CP OPA U2 was heat up very fast , U2 pin4 was 2V ,i had already take off Q4,Q5 . Negative supply for U3 pin4 is -1.5V , U3 pin7 voltage is about 20V.

U1,U2 pin7 is 31V it's normal , but pin4 only a few mV.

Any pro can help me ? thx.

 

[mendimano1]

I have finished the power supply 5 amperes version according to attached schematic and parts list,
i have measured the output voltage it is 40 volts voltage potentiometer works fine i can bring it to zero voltage, as far as current pot it turns on the LED shortly after i increase the current regulation pot,( is it OK?)



PS_Parts_List_10-11-091.pdf

 

[audioguru2]

I have finished the power supply 5 amperes version according to attached schematic and parts list,
i have measured the output voltage it is 40 volts voltage potentiometer works fine i can bring it to zero voltage, as far as current pot it turns on the LED shortly after i increase the current regulation pot,( is it OK?)

The current regulation pot sets the max amount of current the output of this power supply can provide.
RV3 calibrates the max current to be 5.0A.
At zero rotation the warning LED should not light if there is no load.
At half-way rotation the warning LED should light and the output voltage should drop only when the load current tries to be 2.5A or more.
At maximum rotation the warning LED should light and the output voltage should drop only when the current tries to be 5A or more.

 

[mendimano1]

Thank you audioguro for this detailed instructions on how to test the power supply, by the way U1 and U3 op amp are getting hot (U1 a Little bit more) is that normal without any load on power supply, only the voltmeter at the output.

 

[audioguru2]

Thank you audioguro for this detailed instructions on how to test the power supply, by the way U1 and U3 op amp are getting hot (U1 a Little bit more) is that normal without any load on power supply, only the voltmeter at the output.

I am assuming that your your unregulated supply is +40V.
If U1 is an MC34071 then it has an idle current of 2.8mA max which causes heating of 40V x 2.8mA= 112mW. U1 has an output of 12.2V and an output current of 5.6mA so it heats with an additional (40V - 11.2V) x 5.6mA= 161.3mW. Then the total heating is 273.3mW max which will make it warm, not hot.
A tiny little surface-mount package might get hot.
If the circuit is made on a breadboard then the opamp will probably oscillate and get hot.

If U1 is a TLE2141 then it has an idle current of 4.4mA max. Its total heating is 337.3mW max which will make it warm, not hot.

A load on the power supply will reduce the unregulated supply voltage a little which will make opamps U1 and U3 a little cooler. U2 will get a little warmer. 

 

[mendimano1]

My unregulated supply voltage is 41.2 Volts, I'm using TLE2141 op amps, and a 30 volt 10 amps transformer, and a BD139, 2X parallel 10.000 uF 63 capacitors for C1
3 parallel connected output transistors MJ11016 with 0.33 ohm 5 watt resistors connected at the emitter each of them, i have made my own PCB i think maybe i have done some mistakes there, i will try to redo the PCB from teseract so can fit my components.
                           
BEST REGARDS

 

[sparky666]

I would like to build this power supply too. Now I'm making the PCB design for bottom layer only PCB, when I saw that something's wrong with U1(I think).  The Vcc+ pin is at the In- side, and the Vcc- at the In+ side. How is that IC placed there? And one more thing: Can I use TL071CP instead of TLE2141(They are pin compatible, they do the same thing, the price is different)? Any help would be appreciated.

View attachment 41102

 

[audioguru2]

I would like to build this power supply too. Now I'm making the PCB design for bottom layer only PCB, when I saw that something's wrong with U1(I think).  The Vcc+ pin is at the In- side, and the Vcc- at the In+ side. How is that IC placed there?

The schematic shows which parts are connected to which pin numbers. The layout on the datasheet shows which pins are on which side.
Pin 7 connects to the positive supply. Pin 2 is the inverting input that connects to D8 and R4. Pin 3 is the non-inverting input and connects to R5 and R6. Pin 4 connects to the output 0V.

Can I use TL071CP instead of TLE2141?

Not without reducing the supply voltage to it since the supply is 42V without a load and the max allowed supply for a TLE2141 or MC34071 is 44V but the max allowed supply for a TL071 is only 36V.
U3 has its positive supply reduced by a 10V zener diode that can also supply a TL071 for U1 with a max supply of 32V if you want.
U3 must be a TLE2141 or MC34071 because they have inputs that work with a very low negative supply voltage.

 

[szucsi]

HI Audioguru!

This is a nice long topic, with a lot of very usefull messages. I have tried to read all of them, but I have had to give it up - I can not follow the discussion and the crosslinked messages.

Please, would it be possible to create a message with a summary of the modifications and the modified schematics and the partlist? The original problem is the 0-30V PS with 3A maximum output current. One has the original schematics and has the original PCB. What do has to do the owner with this collection to build a working device? No 5A, no 50V, NOTHING! ONLY WHAT WE ORIGINALLY WANTED TO BUY!

Please publish here the new, REALLY WORKING schematics and PCB and partlist for the needed 0-30V/0-3A labor power supply.

Thank you very much: Szucsi from Budapest, Hungary
([email protected])

 

[audioguru2]

The latest schematic and parts list have been posted many times. Some people have posted pcb designs for it.

 

[capacitor120]

Hello, can you tell me if the schematic under the projects page is the latest variation of this PSU ?
If not, is the first post latest schematic ?

If not can you post latest schematic and pcb that is working ?
Thanx

PS 40 pages is really too much to read to find latest stuff, pls post here latest chematic and pcb

PS2 Why don't you update your project page with latest schematic and parts ?

 

[audioguru2]

I don't know when the latest schematic and parts list were posted so here they are again:

View attachment 41109

View attachment 41110

 

[asd512]

Thanx, audioguru,

I can see that it this latest version the required transformer if 28VAC,
but in original only 24VAC,
so I was wondering, since i have a 18VAC transformer can I use it instead of
28VAC(nevest design), or 24VAC(old design under the projects page)

I know than I will get max 23.5 VDC on output, but I don't need more.

Looking forward for your reply...

PS, that newest schematic that you posted, can i use the pcb under the projects page ?

 

[audioguru2]

I can see that it this latest version the required transformer if 28VAC,
but in original only 24VAC

The latest version works perfectly but the original version does not work properly.

since i have a 18VAC transformer can I use it instead of
28VAC(nevest design), or 24VAC(old design under the projects page)

I don't know if an 18V transformer will work without analysing the current in nearly every resistor, then changing some of their values.
18VAC has a peak of 25.5V and the rectifier bridge drops the positive unregulated supply to 23.5V. The losses in the circuit are about 6V so the max output voltage at 3A will be about 17.5VDC.

The circuit will work with a 24VAC transformer but the max output voltage at 3A will be about 26VDC. The unregulated positive supply is 34.7V plus the negative 5.6V supply makes a total supply of 40.3V. The opamps in the original design have an absolute maximum total supply of only 36V. The 24V transformer is overloaded in the original circuit when the load is 3ADC. Many parts in the original circuit overheat especially Q2.

PS, that newest schematic that you posted, can i use the pcb under the projects page?

The original circuit uses many parts that are too small so they overheat. The latest version uses larger parts that do not fit on the original pcb. The latest version has calibration trimpots and a few other parts added.
Some people have posted their pcb designs for the latest version but I didn't save them.

 

[bean1028]

Ok, I have been following this and waiting for a transformer to build this since last year, and the other day I finally ran across a microwave and decided to try my hand at rewinding it (thanx to... Audioguru? Whoever it was that did this for the idea). Well, after a couple of failed attempts using the wrong wire, I ended up with a 31.2v transformer. No clue of the amperage or how to test it, but the voltage is there! Now before I begin, I must revert to and rephrase the question asked a few posts back-Why all the different versions? Everyone keeps asking for the schematic which is posted 6 times on every page, and with everything being posted in the first 3 posts in this thread that boggles my mind-but that's not my question. Here it is: Why is everyones power supply in need of mods to work? And to be a different problem with every person? Electricity is always electricity... So with that being said, does anyone have any advice for me to build this and have it work the way it is supposed to? The first time? Also, any tips on how to check the amps of the x-former for use on the 5amp version, or should I stick with the 3amp version? One last thing... To Audioguru and those who helped design the original working psu-which op-amp? MCU or TLE?

 

[bean1028]

Also, lookin at the TLE2141 on Farnell it is listed as having a max input of 22v, where here it is listed as 44v. What are the key points to consider for the op-amp if I decide to use a different one? I have several lm's and others laying around, as well as a bunch of tl081's I bought to make the first version.

 

[audioguru2]

Hi Bean,
The original project had many errors so it did not produce 30VDC at 3A but instead produced about only 25VDC with lots of ripple at 3A.
Many of its parts overheated especially the old fashioned and tiny transistor Q2 and the transformer.
The unregulated supply was a total of 40.3V without a load but the opamps in the original project have an absolute max total supply of only 36V.

I corrected some of the problems 5 years ago by using OPA445 high voltage opamps, a more powerful Q2 transistor and a few other changes but then this opamp became hard to find and expensive. So the latest version uses two types of opamps that are available almost anywhere, do not need a huge negative supply voltage and have a max total supply of 44V.

The datasheet is what you should look at because maybe Farnell missed that the max supply voltage for the TLE2141 is plus and minus 22V which is a total of 44V.

The latest version has a small negative supply for U3 and no negative supply for U1 and U2. Most opamps do not work with a small negative supply or no negative supply. The opamps for the latest version were selected because they work perfectly with a small or no negative supply voltage.

 

[bean1028]

Thank you Audioguru. I am going to build the 5amp that... Redwire? built... I am going to try to use the exact parts he used to try and avoid the endless troubleshooting. Another bonus is that since we are both using microwave transformers I might luck out and have a near identical power source eliminating all the problems I have read about concerning this. At worst I think I might end up short on x-fmr amps, but I will have a psu with a 5A potential.

I was wondering if that was the case with the opamps, but I have never seen a use for negative voltage so I have never had to consider that.

Also to correct myself in my last post: I said "MCU or TLE", and realized there is no U in the MCU part number. oops.

 

[audioguru2]

The difference between a 3A project and a 5A project:
1) The 28V transformer must be 119W for the 3A project and must be 198W for the 5A project.
A little 28V x 3A= 84W or 28V x 5A= 140W transformer will be overloaded.
2) The 3A version uses two output transistors with emitter resistors and the 5A project uses three output transistors with emitter resistors.
3) R7 is 0.47 ohms/10W for 3A and is 0.27 ohms/10W for 5A.
4) The heatsink for the output transistors must be able to dissipate 109.8W for 3A or 183W for 5A. 

 

[bean1028]

Ok. I just ordered everything off newark (xcept xfr) for just over 20$. Actually, I got 3 of almost everything just in case. I ordered 3 power transistors in case I build the 5amp. I decided not to be cheap and bought some Aavid heatsinks with a thermal resistance of 4 degrees/w. Ok that was a lie, I did go cheap-they were 6 for 3 dollars, another 3 for shipping brand new. I was ready to pay 20+ if I had to, don't tell the seller that. I have an 1100 watt 250 dollar stainless microwave that works great but would work better if the xfer was rewound. I think I am going for the 5 amp. You guys put way too much effort into making such a wonderful product accessible to poor people like me, so I am going to make sure y'all's work is put to good use.

Thank you everyone with your infinite patience for helping us newbies through this, it is people like you who donate their time so that others can benefit that makes the internet so damn useful. We all appreciate you. Now wish me luck I am going to go electrocute myself.