design of circuit for 0-24v 5amp regulated power supply

[VickySalunkhe]

I am noobie so plz help and co-operate

I was thinking to use 12-0-12V 5A center tap transformer

I know by connecting 2 12v wires I'll be getting required 24v ac but i am stucked at which components shall be used and how, for making regulated power supply

My ultimate aim is to make an 48v 5amp power supply to run an electric motor

So just thought I'll make 2 , 24v 5amp power supplies which could then be connected in series for getting the required 48v 5Amp as an output

If you could help me with designing a circuit for making an 24v 5amp regulated power supply that will be really helpful

I have found a circuit for 24V 1amp

But my requirement is for 5amp and i am not sure which components should be replaced

Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view
Image is also attached

Any suggestion and help will be appreciated

Thnks

[Ian.M]

Comes from: https://www.eevblog.com/forum/beginners/how-to-make-regulated-power-supply-of-0-48v-5amp-using-24-0-24-v-5amp-center-t/
Basic Technical Forum Etiquette: Please don't start multiple new topics for the *SAME* project unless your new question is totally unrelated to your previous questions or the previous topic has jumped the rails and the discussion has gone way off into the long grass of stuff you don't understand and have no interest in.  Otherwise your readers have to research your previous posts in other topics to get the broader picture of what you already know, have and can do, which wastes our time and yours.  If a previous topic jumped the rails, link to it , but mention that after post #n you no longer found it helpful and why.  (N.B. I am not an administrator here and these are just strong recommendations, not official rules)

The quick answer to "But my requirement is for 5amp and i am not sure which components should be replaced" is *ALL* of them except the power LED.   Yes there are circuits that boost the output of a LM317 regulator, but unless you design is good, you loose the thermal overload protection, and they invariably require more headroom than the original unboosted circuit.    If you want an easy intro to higher current linear PSU circuits, consider using the LM723 with external pass transistors.

[IanB]

My ultimate aim is to make an 48v 5amp power supply to run an electric motor

As Ian.M said, please do not ask the same question twice in two different topics.

However, you do not normally need a regulated power supply to run an electric motor, unless it is a special motor. Normally just a rectified output from a transformer will be sufficient.

[Zero999]

As Ian said, a regulated power supply is not required for a motor.

One thing which might be an issue is the motor start up current, which with a load with a lot of inertia, can easily last longer than that taken by a smoothing capacitor. Make sure the rectifier diodes are overrated and use slow blow fuses, so they don't blow when the motor starts.

[VickySalunkhe]

hello hero999

thnks for your help
can you plz tell me where should i keep the fuse in the circuit
and what should be its specification
as i am going to work with 5Amp current.

[VickySalunkhe]

thanks IanB for your help

i asked the question once again as  i found out taking out 48V 5Amp from transformer as DC its tough and i was not able to search for the components which will support the requirements
lm338 is there but voltage range is 2.5 to 32 V

thats why i thought to change it to making 2 24V 5Amp power supply and will connect it in series

can you suggest me which capacitor, resistor,transistor and fuse should be used?

your help will be really appreciated 

[IanB]

I think you are asking the wrong questions. You think you need a regulated DC power supply, but you may be wrong. If you tell us what you want to do with the power supply you may get better answers. For example, if you want to run a motor maybe you don't need any capacitors or voltage regulators at all.

So instead of asking how to make something, tell us instead what problem you are trying to solve and ask for help solving that problem.

[VickySalunkhe]

okay may be because i am completely new to this concept

i need to run motor rated at 48V 500W dc motor

at first instead of buying batteries which will cost too much at such an early stage i thought to build a power supply
and give it to the motor

previously i have started the motor using 2 regulated power supply unit in series of 30v 500mA by setting the voltage 24v on each psu

but now i don't have access to those psu so thought to make of my own

what do you suggest?

thanks

[neo]

I am noobie so plz help and co-operate

I was thinking to use 12-0-12V 5A center tap transformer

I know by connecting 2 12v wires I'll be getting required 24v ac but i am stucked at which components shall be used and how, for making regulated power supply

My ultimate aim is to make an 48v 5amp power supply to run an electric motor

So just thought I'll make 2 , 24v 5 amp power supplies which could then be connected in series for getting the required 48v 5Amp as an output

If you could help me with designing a circuit for making an 24v 5amp regulated power supply that will be really helpful

I have found a circuit for 24V 1amp

But my requirement is for 5amp and i am not sure which components should be replaced

Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view
Image is also attached

Any suggestion and help will be appreciated

Thnks

Now there are more elegant ways to do it but the easiest way would be to get two over rated transformers that can put out 24VAC, in your example of 12-0-12 transformer aim for 12 amps total rating from each transformer.
Wire up each transformer to a separate bridge rectifier and smoothing capacitor, the smoothing capacitors should be rather large about 20,000 uf if absence of ripple matters at all.
At this point check that the DC output is in fact between 37-39V out of the capacitors, if it is a little high you can use a 10A rated diode to drop it though this may cause issues at higher currents.
If it is a little below 37 don't worry too much as it would only mean a slight decrease in total output voltage, if the voltage is correct you can use two LM338 regulators linking one's output to the ground of the second.
Feel free to ask for more details.  Also for this to work without blowing up you would need a rather large slab of metal to serve as a heat sink, if you would like to avoid using a heat sink there are adjustable switch mode supplies available that could be used without a heat sink and in place of the LM338.

http://www.ebay.com/itm/XL4016-DC-DC-Buck-Step-Down-Power-Module-4V-40V-to-1-25V-36V-8A-200W/192211314397?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

All of this arguably irrelevant for a motor driver but it is what you asked for in the title.

[IanB]

okay may be because i am completely new to this concept

i need to run motor rated at 48V 500W dc motor

at first instead of buying batteries which will cost too much at such an early stage i thought to build a power supply
and give it to the motor

previously i have started the motor using 2 regulated power supply unit in series of 30v 500mA by setting the voltage 24v on each psu

but now i don't have access to those psu so thought to make of my own

what do you suggest?

thanks

OK, but still more information would be helpful. You say the motor is 48 V 500 W, which means it will draw over 10 A at full load. And yet you say you have run the motor with a 500 mA power supply, which is much less than 10 A.

Therefore, what do you want to do with the motor? Will it be powering some machine, or do you just want to see it run? The amount of power drawn by a motor depends on how much you load it. If you just want to see it spin, you don't need that much power. You probably don't even need 48 V. It will run on 24 V or even 12 V.

So you see, the answer all depends on what you will use the motor for.

If you want to power the motor and just make it run, then you can get a suitable transformer, put a bridge rectifier on the output (a big one, suitable for the required current), and connect that directly to the motor. There is no need for any electronics at all.

Next, if you want to vary the speed of the motor, a voltage regulator is not the way to do it. You will want some kind of motor speed controller that switches the power on and off very fast, like a thyristor controller or a PWM controller.

[VickySalunkhe]

Thanks IanB for your reply
Actually i have a throttle and control unit which supplies power to the motor accordingly

Motor , its actually an dc hub motor
I am working on e bike
I am from Computer engg field so my knowledge about electronic and electrical field is not good

Motor specification
throttle voltage 30V
At the later stage i am going to use li ion batteries but for now i am thinking to make regulated power supply.

For now i am thinking to build 2  24v 5A regulated power supply and will connect it in series
Using center tap transformer ill get more than 29 v from one power supply
So thought to make an regulated psu so i can test the motor under various voltage levels
Varying between 32-53V

From some source i found out 12-0-12v 5amp will not produce 5amp supply and now i was curious why not?
So plz guide me how can i achieve this?

I have found this circuit but its for 24v 1Amp and my power requirement is 5amp
Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view

Thanks a lot 

[neo]

Thanks IanB for your reply
Actually i have a throttle and control unit which supplies power to the motor accordingly

Motor , its actually an dc hub motor
I am working on e bike
I am from Computer engg field so my knowledge about electronic and electrical field is not good

Motor specification
throttle voltage 30V
At the later stage i am going to use li ion batteries but for now i am thinking to make regulated power supply.

For now i am thinking to build 2  24v 5A regulated power supply and will connect it in series
Using center tap transformer ill get more than 29 v from one power supply
So thought to make an regulated psu so i can test the motor under various voltage levels
Varying between 32-53V

From some source i found out 12-0-12v 5amp will not produce 5amp supply and now i was curious why not?
So plz guide me how can i achieve this?

I have found this circuit but its for 24v 1Amp and my power requirement is 5amp
Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view

Thanks a lot 

The LM317 is the little cousin to the LM338 i mentioned earlier, all you would really have to do is change regulators. Perhaps read my earlier post?
Also a 5 amp rated supply won't deliver 5 amps because, simply put, it is only rated for 5 and in reality there is always loss in linear circuits. So in simple terms if you want 5 amps usable at peak voltage aim for 12 amps or so rated transformer.
More complex terms as to why a 5 amp supply won't deliver 5 amps. OK if you have 24VAC out of a transformer that is 5 amp rated that is at 24V RMS whereupon converting to DC you get the peak to peak voltage smoothed, so 24V would become near 40V which would in effect half the current at its upper voltage limit. Besides that any circuitry will impose some resistance, especially linear no matter how good, so then there is some loss already however the problem is further compounded by the efficiency which in linear supplies and regulators is typically 50% or below. Nothing is perfect, even switching supplies top out at 98% at the cost of imposing high frequency noise  but i digress. Hope this helps.

[VickySalunkhe]

Now there are more elegant ways to do it but the easiest way would be to get two over rated transformers that can put out 24VAC, in your example of 12-0-12 transformer aim for 7 amps total rating from each transformer.
Wire up each transformer to a separate bridge rectifier and smoothing capacitor, the smoothing capacitors should be rather large about 20,000 uf if absence of ripple matters at all.
At this point check that the DC output is in fact between 37-39V out of the capacitors, if it is a little high you can use a 10A rated diode to drop it though this may cause issues at higher currents.
If it is a little below 37 don't worry too much as it would only mean a slight decrease in total output voltage, if the voltage is correct you can use two LM338 regulators linking one's output to the ground of the second.
Feel free to ask for more details.  Also for this to work without blowing up you would need a rather large slab of metal to serve as a heat sink, if you would like to avoid using a heat sink there are adjustable switch mode supplies available that could be used without a heat sink and in place of the LM338.

http://www.ebay.com/itm/XL4016-DC-DC-Buck-Step-Down-Power-Module-4V-40V-to-1-25V-36V-8A-200W/192211314397?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

All of this arguably irrelevant for a motor driver but it is what you asked for in the title.

Thanks neo for your rply

But i didn't get why did you mention voltage range 37-39V
Does single 12-0-12V transformer going to output that much voltage?

And you mentioned if voltage are okay use two lm338 sry but i didn't get why to use two?

What i am thinking is build 2 separate 24V 5amp regulated psu
And then I'll connect it in series to get 48V 5amp dc
Am i correct?

Or if there is some other method which will be good plz suggest me


Your help is really appreciated
Thanks a lot 

[VickySalunkhe]

The LM317 is the little cousin to the LM338 i mentioned earlier, all you would really have to do is change regulators. Perhaps read my earlier post?
Also a 5 amp rated supply won't deliver 5 amps because, simply put, it is only rated for 5 and in reality there is always loss in linear circuits. So in simple terms if you want 5 amps usable at peak voltage aim for 12 amps or so rated transformer.
More complex terms as to why a 5 amp supply won't deliver 5 amps. OK if you have 24VAC out of a transformer that is 5 amp rated that is at 24V RMS whereupon converting to DC you get the peak to peak voltage smoothed, so 24V would become near 40V which would in effect half the current at its upper voltage limit. Besides that any circuitry will impose some resistance, especially linear no matter how good, so then there is some loss already however the problem is further compounded by the efficiency which in linear supplies and regulators is typically 50% or below. Nothing is perfect, even switching supplies top out at 98% at the cost of imposing high frequency noise  but i digress. Hope this helps.

Thanks neo for your reply

So what do you suggest for which transformer (or how many) should i opt for so that i can fulfill my requirement of giving as supply voltage between 32V to 53V to the dc motor

Thanks

[neo]

Now there are more elegant ways to do it but the easiest way would be to get two over rated transformers that can put out 24VAC, in your example of 12-0-12 transformer aim for 7 amps total rating from each transformer.
Wire up each transformer to a separate bridge rectifier and smoothing capacitor, the smoothing capacitors should be rather large about 20,000 uf if absence of ripple matters at all.
At this point check that the DC output is in fact between 37-39V out of the capacitors, if it is a little high you can use a 10A rated diode to drop it though this may cause issues at higher currents.
If it is a little below 37 don't worry too much as it would only mean a slight decrease in total output voltage, if the voltage is correct you can use two LM338 regulators linking one's output to the ground of the second.
Feel free to ask for more details.  Also for this to work without blowing up you would need a rather large slab of metal to serve as a heat sink, if you would like to avoid using a heat sink there are adjustable switch mode supplies available that could be used without a heat sink and in place of the LM338.

http://www.ebay.com/itm/XL4016-DC-DC-Buck-Step-Down-Power-Module-4V-40V-to-1-25V-36V-8A-200W/192211314397?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

All of this arguably irrelevant for a motor driver but it is what you asked for in the title.

Thanks neo for your rply

But i didn't get why did you mention voltage range 37-39V
Does single 12-0-12V transformer going to output that much voltage?

And you mentioned if voltage are okay use two lm338 sry but i didn't get why to use two?

What i am thinking is build 2 separate 24V 5amp regulated psu
And then I'll connect it in series to get 48V 5amp dc
Am i correct?

Or if there is some other method which will be good plz suggest me


Your help is really appreciated
Thanks a lot 

I have built a few 5 amp supplies and every time i have built one i find 24VAC puts out up to 40VDC once rectified and smoothed, as said this is because it is the peak to peak voltage. 
You don't have to use two LM338s, the only problem with one is that it only outputs about 1.2 to 35VDC regulated, you need about 37VDC in to get that because of the aforementioned efficiency and a small voltage drop. I said two because you said your ultimate aim was a 48VDC 5 amp supply which can be achieved if you have two separate LM338 power supplies linked in series.
As for a transformer, all you need is two 24VAC windings, so this could either mean two 24VAC 12A transformers with their primaries linked in parallel or one big transformer with two separate 24VAC windings, very important for functionality separate NOT 24-0-24VAC, with a 12 amp rating on each winding.
Also an important mention if you are going to build an LM338 supply then i would recommend two things.
First to keep in mind you will need a large heat sink about 5 pounds with forced air cooling, bigger is better though.
Second, buying spares because you will blow at least one up learning, i did,  and i have found some difference between regulators with their power handling.

[VickySalunkhe]

Thanks neo

I just had a thought
What will happen if I'll use 24-0-24V 5Amp center tap transformer
If ill use wire 1and 3 with a bridge rectifier I'll get 48V

But what will happen if I'll use wire 1 and 2 with a bridge rectifier
And wire 3 and 2 with another bridge rectifier
As far as i see wire 1 and 2 will generate positive 24V dc
And wire 3 and 2 will generate negative 24dc

So is there a way i can convert that second way to positive and somehow connect those two power supply wires in series to get 48V

Am i thinking right
Or all this stuff is actually wrong?

Sry for too much confusion but i am trying to know what and how they are going to work..

Thanks a lot...

[neo]

Thanks neo

I just had a thought
What will happen if I'll use 24-0-24V 5Amp center tap transformer
If ill use wire 1and 3 with a bridge rectifier I'll get 48V

But what will happen if I'll use wire 1 and 2 with a bridge rectifier
And wire 3 and 2 with another bridge rectifier
As far as i see wire 1 and 2 will generate positive 24V dc
And wire 3 and 2 will generate negative 24dc

So is there a way i can convert that second way to positive and somehow connect those two power supply wires in series to get 48V

Am i thinking right
Or all this stuff is actually wrong?

Sry for too much confusion but i am trying to know what and how they are going to work..

Thanks a lot...

24-0-24VAC would work to build a power supply, each half going to a separate bridge rectifier with the center tap being ground. The problem with this is that it, once smoothed, it would be two 37-40VDC supplies with common ground, perfect for a dual channel supply but incapable of being linked in series.
Also worth mentioning is that the only difference between 24-0-24VAC and two separate 24VAC windings is that the center tap has the windings in series.

[VickySalunkhe]

So shall i use 2   12-0-12V 5Amp center tap transformer
And make 2 separate regulated psu using those transformer
And then connect them in series?

As you said I'll get 37v from 1 psu so i can adjust both psu to 24v then connect it in series i can easily staisfy my moto
Am i Right?

Amd if i am right
Can you plz suggest me changes required in
Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view

Other than
Lm338 ,10Amp diodes and capacitor of 20000uf
As u suggested


There are other components left like 2 more cap
And 3 resistors what about them?


Thanks a lot neo really appreciate your help
 

[neo]

So shall i use 2   12-0-12V 5Amp center tap transformer
And make 2 separate regulated psu using those transformer
And then connect them in series?

As you said I'll get 37v from 1 psu so i can adjust both psu to 24v then connect it in series i can easily staisfy my moto
Am i Right?

Amd if i am right
Can you plz suggest me changes required in
Link to circuit
https://drive.google.com/file/d/0B0H4hwbNhR-GTkRHQ0ZjY2dDTWM/view

Other than
Lm338 ,10Amp diodes and capacitor of 20000uf
As u suggested


There are other components left like 2 more cap
And 3 resistors what about them?


Thanks a lot neo really appreciate your help
 

The pleasure is mine, i like linear supplies.
12-0-12V will work but it will need to be more than 5 amp rated, as i said 12A at 24VDC is only 7A at 40VDC  and as i have also said overrate. For example 10A at 24V  would in theory work but may not be able to provide the full 5 amps at the desired voltage.
Also it makes for a better supply, better adjustability,  if for the 5K potentiometer you were to use a ten turn potentiometer. Of course that is strictly optional.

[VickySalunkhe]

So do i need to change the rest of the components or not ?

other than the transformer rating, diodes, lm338 and cap u stated

Thanks neo you really have helped to clear out some concepts

[neo]

So do i need to change the rest of the components or not ?

other than the transformer rating, diodes, lm338 and cap u stated

Thanks neo you really have helped to clear out some concepts

Higher current rated diodes and an LM388 are all that are really needed, i recommend changing the capacitor to a larger value for reduced ripple though that is strictly optional.

[neo]

Also, with the LM338 you will need a large heat sink, about 5 pounds with forced air cooling for both. Bigger is of course better when it comes to cooling.

[Zero999]

All right, it sounds like you do need a regulated power supply after all, but do you really have to make one? Perhaps you should look at buying a 500W 48V power supply first? I doubt it would be cheaper to build one.
http://www.mouser.co.uk/ProductDetail/Mean-Well/RSP-500-48/?qs=8uyp%2fy7yFW51E4MJhz7yTA==

I'm still confused as to whether 5A or 10A, 24V or 48V is required?

One thing to bear in mind, with TO-220 regulators, such as the LM338, is the maximum practical power dissipation, for that package type, is around 50W, so you'll only be able to get 5A out, when the difference between the input and output voltage is under 10V.

The maximum differential voltage for the LM338/317 is 40V, which can also be problem because with 24V or more out, it's likely you'll need a transformer which will give over 40V, after the rectifier, which will destroy the regulator, if it ever goes into current limiting mode.

The output current and power dissipation of the LM317 can be increased by adding by pass transistors.


A cascode and zener diode, can be used to overcome the maximum 40V differential rating.

[Avacee]

You could buy one and reverse engineer it for around £25.
http://www.ebay.co.uk/itm/DC-48V-10A-Universal-Regulated-Switching-Power-Supply-for-Computer-Project-OL-/282556976292
http://www.ebay.co.uk/itm/DC-3V-5V-12V-24V-36V-48V-Universal-Regulated-Switching-Power-Supply-LED-CCTV-PSU-/151886747221
http://www.ebay.co.uk/itm/Universal-DC48V-8-3A-Regulated-Switching-Power-Supply-Transformer-Switch-SU-/282535948603

Though at those prices you're probably more likely to learn how to make something with zero to few safety features.

[neo]

All right, it sounds like you do need a regulated power supply after all, but do you really have to make one? Perhaps you should look at buying a 500W 48V power supply first? I doubt it would be cheaper to build one.
http://www.mouser.co.uk/ProductDetail/Mean-Well/RSP-500-48/?qs=8uyp%2fy7yFW51E4MJhz7yTA==

I'm still confused as to whether 5A or 10A, 24V or 48V is required?

One thing to bear in mind, with TO-220 regulators, such as the LM338, is the maximum practical power dissipation, for that package type, is around 50W, so you'll only be able to get 5A out, when the difference between the input and output voltage is under 10V.

The maximum differential voltage for the LM338/317 is 40V, which can also be problem because with 24V or more out, it's likely you'll need a transformer which will give over 40V, after the rectifier, which will destroy the regulator, if it ever goes into current limiting mode.

To the underlined bit, this problem can be solved with a variac, at least i have done that.
It may be cheaper to buy one but it is educational to build one.