5 Ampere Regulator using LM 317 or LM723

[BigBoss]

All those are old stuff..
Look at this one.Discover the circuit because it has a ability to work in parallel to increase the supplied current.
http://www.linear.com/product/LT3081
http://www.linear.com/docs/45095

[Gurumurthy]

Dear all,

         Nothing went well for past 4 months with IC Regulators.
So i decided to construct 30V @ 90 W it means 3A Load Current. Please Suggest me the circuit which could Do vary from 0-30V and 0-3A voltage and Current . I want to construct as a dual power supply with two separate transformers of  24V@3Ampere.Suggest me a circuit to Learn and Construct the circuit.Thousands of thanks to the members of the  forum.

[Zero999]

Dear all,

         Nothing went well for past 4 months with IC Regulators.
So i decided to construct 30V @ 90 W it means 3A Load Current. Please Suggest me the circuit which could Do vary from 0-30V and 0-3A voltage and Current . I want to construct as a dual power supply with two separate transformers of  24V@3Ampere.Suggest me a circuit to Learn and Construct the circuit.Thousands of thanks to the members of the  forum.

What have you being doing for the last four months?

What problems have you had with IC regulators?

Try the following schematic. It's also available in kit form but will need to be modified, in order to be reliable. If you want two outputs, then make two of them. You might be able to save some of the cost by using a transformer with two secondary windings, although you shouldn't expect the insulation between them to withstand more than 100VDC or so.


https://www.eevblog.com/forum/beginners/bangood-psu-enhancements/msg897563/#msg897563

[wasyoungonce]

If you search the OPs posts..he has been posting every few weeks asking for a Linear PSU design either LM723/LM317/LM338.  He kinda either doesn't like what he's been told or doesn't understand it or doesn't have parts on hand (and wants us to substitute for him) ....thus keeps asking the same thing.  He as also doesn't reply or explain what problems he is having...all very vague, then disappears only to start another thread.

This same question has been posted over a dozen times by the OP so far and borders on spamming (he is know to double and triple cross post on different threads).  Now no one minds helping but this is beyond a joke atm.

....The OP is well known to spam the whole forum again and again with new thread on the same subject, when he didn't find any schematic that he likes, or no one answer him within a day. Looks like he doesn't like circuit that has too many components, or circuit that uses components that are not in his drawer.

Just read his past created threads. 

Also I did ask him a simple yet very important question on his 1st thread, but it seems like he ignored me. 

I'm guessing that what he want is only a circuit that consist of max 2 transistors and few capacitors and a LM317 to build an adjustable 0-30V and 0-5A complete with with CC and CV feature.

Watch for his upcoming newly created thread as he doesn't like to use the 723 anymore. 

[Zero999]

If you search the OPs posts..he has been posting every few weeks asking for a Linear PSU design either LM723/LM317/LM338.  He kinda either doesn't like what he's been told or doesn't understand it or doesn't have parts on hand (and wants us to substitute for him) ....thus keeps asking the same thing.  He as also doesn't reply or explain what problems he is having...all very vague, then disappears only to start another thread.

This same question has been posted over a dozen times by the OP so far and borders on spamming (he is know to double and triple cross post on different threads).  Now no one minds helping but this is beyond a joke atm.

....The OP is well known to spam the whole forum again and again with new thread on the same subject, when he didn't find any schematic that he likes, or no one answer him within a day. Looks like he doesn't like circuit that has too many components, or circuit that uses components that are not in his drawer.

Just read his past created threads. 

Also I did ask him a simple yet very important question on his 1st thread, but it seems like he ignored me. 

I'm guessing that what he want is only a circuit that consist of max 2 transistors and few capacitors and a LM317 to build an adjustable 0-30V and 0-5A complete with with CC and CV feature.

Watch for his upcoming newly created thread as he doesn't like to use the 723 anymore. 

Yes, I'm aware of this. I decided to make one last ditch effort to help. In future I'll just post links to what has already been advised.

Some may argue that, you shouldn't post as you've done and that if you don't have anything helpful to say, then don't say anything but I'd disagree. If you warn others that someone is being unreasonable, then it helps them avoid wasting their time on them.

[Gurumurthy]

Thanks a lot to all.

                I need an solid understanding before constructing the circuit. If two much component is present, better we can simulate the circuit but it does not show temperature effects. just show the waveform of the circuit at various nodes.

               I must know to analyse the big circuit. i know i should use divide and conquer approach but my knowledge is not enough to understand which part does what operation. That is why i have fear in constructing circuit.

               I am college learner, where will i get sufficient time to understand huge chunk of circuit.
 
               I need both quantitative and qualitative analysis of circuit. No text book is good for this constructing of regulated power supplies. they does nt reveal the principle behind the operation. they hide principles and give schematics for constructing..

               what i have learnt from all these thread is ,there is a limit for Linear and Smps power supply.

                                            for low power go for Linear mode and for high power go for smps pregulator and LDO post regulator, this avoid over heating of LDO regulators.

                                         IC regulators have safer operating limits, so we cant expect required current at all conditions. this is where it fails.most of my initial design were with LM317 and LM723. these were selected merely due to its cost. I wont get 100 rupees as pocket money.

                                        This student is not arguing to make this mistake were resonable but this were the conditions which made to ask multiple threads.     
 
                                        I never had an intention of ignoring all your advices. I swear for this... I respect all ur advices.

[colinza]

Don't try this at home, kids! 

So I have a prototype box where I play with power supply designs. The current iteration in it is surely insane but it works quite well, and is actually similar to this idea.

It uses an LM317 but only to produce a low current 30V reference from 24V RMS transformer. I then use that to drive an LM358 way beyond spec and very close to exploding. The 358's input is a DAC with a 4v reference and then the opamp has a 10X gain and the a second stage provides the feedback from a TIP3055 to do the actual higher current linear regulation.

Inefficient, very sketchy, needs short circuit protection added because high current surges will blow the opamp - luckily the DAC survives, and it needs to accept the fact that it can't really handle 30V output. I don't actually trust it, but it does provide negative rail too





Software side is an arduino mini, CC is currently in software (eek!). The LCD is a raspberry pi that controls the arduino via serial. The code is here https://github.com/calston/piwerlab

But the biggest purpose this serves in my lab is a set of touch screen controlled relays for 6x IEC AC connectors at the back which goes to my soldering iron, scope, etc.

[Zero999]

I don't see a heat sink. Is the main power transistor hidden somewhere?

[colinza]

I don't see a heat sink. Is the main power transistor hidden somewhere?

They're off in the picture, or else you'd just see two big heatsinks and fans. Two CPU heatsinks clamp onto the top of the transistors which are oriented backwards as you can see

[Gurumurthy]

Dear All,

     I have attached L200 Schematic which is programmable voltage and current regulation.
My doubt is the function of operational amplifier? the 0.1 ohm resistor is current sense resistor . when the load ia 1A it has a drop of 0.1V . Accordance to me , it is an difference amplifier which amplifies this o.1V.
 The output of OPamp Could be =(p1/R2)*0.1V.

How L200 is going to do regulation by varying P1 resistor? What is the function of operational amplifier?

[BigBoss]

Another good-looking design..I have never checked but it seems principally working

[Kleinstein]

Another good-looking design..I have never checked but it seems principally working

The circuit is a variation of the classic floating regulator.

It uses a rather odd way to have a minimum load to the regulator. There is a simpler way using the upper auxiliary supply for this.  The way of adjusting the voltage was common in the old days, but has the disadvantage of having regulator loop gain depending on the set voltage. It is usually better to do the adjustment from the reference voltage side - this comes naturally when you change to digital voltage adjustment.  The way the extra sense inputs looks a little like an after-thought. It should work, but might cause trouble when higher impedance (e.g. open) and the 100 Ohms resistors would need to be high power, as they have no extra protection.

Having the LEDs to do the min voltage function can be borderline on the reverse voltage rating, depending on the OPs used.

[IanMacdonald]

You have some good variable smps circuits on ebay going down to zero with decent protection,  just add main transformer rectifier and capacitor

Used quite a few in the past. Like most Chinese stuff some are good, others not so.  Most are only rated for up to 30v or 35v and 3A though, so pushing things a bit for this project.  Also don't necessarily believe claims of higher ratings. Usually the same product from a dodgy seller, exaggerating.

Basically if you want to handle that kind of power linearly, you need at least a couple of paralleled TO3 or TO247 devices on a decent h/s. Forget using TO220 devices, they have too high a chip-to-case thermal resistance. Also I would go for an opamp arrangement, a bit more work to build but better control than grafting power transistors onto a regulator chip.

"If you search the OPs posts..he has been posting every few weeks asking for a Linear PSU design either LM723/LM317/LM338."

Point taken. Should have noticed that. Anyway, basically a case of trying to squeeze a quart out of a pint pot. Better to do the job with the right parts.