[wolfdagon]

I found a 48V power supply for about $40 but it is only 2 amps. Is it possible to modify it to give 8-10 amps? If so, how hard/expensive would it be? Could I make an easy change which would sacrifice some voltage for more amps? If I could get it to 40-42V and 8-10 amps that would be great.

[holbieone]

i don't think it will work for that much change

first you need to know how many amps the transformer will kick out

then you can replace the bridge rectifier or diodes with ones that are rated for higher amps

do a Google for power supply schematics

[wolfdagon]

Probably a silly question but if I got two 24V 5A supplies could I connect them to make a 48v 10A supply?

[CJL5585]

Probably a silly question but if I got two 24V 5A supplies could I connect them to make a 48v 10A supply?

NO

If you wired the supplies in series, you would have 48 Volts at 5 Amps.

If you wire them in Parallel, you would have 24 VDC at 10 Amps.

Jerry

[FPV_GTp]

I found a 48V power supply for about $40 but it is only 2 amps. Is it possible to modify it to give 8-10 amps? If so, how hard/expensive would it be? Could I make an easy change which would sacrifice some voltage for more amps? If I could get it to 40-42V and 8-10 amps that would be great.

Hi wolfdagon

have a look at this thread http://www.cnczone.com/modules.php?n...warticle&id=27 there is more information on the front home page on www.cnczone.com

Hope this article is of help , that is the problem with website so much information on here , i need to take a speed reading course to increase my reading speed from 20 words a minute to 1500 words a minute

cheers

[max_imum2000]

my company uses switching powersupply a lot.
very nice size and very light weigh compared to the transformer type (3kg only).
they come in 48v 10amp, and 48v 20amp
i think the price is 180$ for the 10amp, i can send you few if anyone intersted.

[wolfdagon]

NO

If you wired the supplies in series, you would have 48 Volts at 5 Amps.

If you wire them in Parallel, you would have 24 VDC at 10 Amps.

Jerry

Okay, That makes sense.

Two more questions, then.

1) Is it more important to have more volts or more amps? I have now found a few identical 24V 7.2A power supplies. If I am understanding everthing that I have read in the zone I need around 32V 6A for my three motors, so I could wire two of these in series and be ok. However, I would like to be able to add a fourth axis later. This would require 42V 8A. Would the 7.2 A make that much difference?

2)If so, would it be possible to wire up three of these supplies in a combination of series parallel to get what I need? Again, maybe a stupid question.

Thanks for all replies.

[holbieone]

Okay, That makes sense.

Two more questions, then.

1) Is it more important to have more volts or more amps? I have now found a few identical 24V 7.2A power supplies. If I am understanding everthing that I have read in the zone I need around 32V 6A for my three motors, so I could wire two of these in series and be ok. However, I would like to be able to add a fourth axis later. This would require 42V 8A. Would the 7.2 A make that much difference?

2)If so, would it be possible to wire up three of these supplies in a combination of series parallel to get what I need? Again, maybe a stupid question.

Thanks for all replies.

if you have 3 12volt 2amp motors you will need a 12volt 6amp power supply

adding another 12volt 4amp motor you will need a 12volt 10amp power supply

if the motors are different voltages you will need a power supply for each voltage

[sdantonio]

I found a 48V power supply for about $40 but it is only 2 amps. Is it possible to modify it to give 8-10 amps? If so, how hard/expensive would it be? Could I make an easy change which would sacrifice some voltage for more amps? If I could get it to 40-42V and 8-10 amps that would be great.

I read something on the xylotek page a long time ago. If I remember it right their claim was even though your motors may be rated for 5A, 3 motors may work fine on considerably less (i.e. you don't need anywhere near 15A for the system). I don't know if that argument is specific to something in the chipset they use or if that can be made as a general argument.

Now if you have 4 of those 24VDC power supplies... then your in business.

[sdantonio]

Okay, That makes sense.

Two more questions, then.

1) Is it more important to have more volts or more amps? I have now found a few identical 24V 7.2A power supplies. If I am understanding everthing that I have read in the zone I need around 32V 6A for my three motors, so I could wire two of these in series and be ok. However, I would like to be able to add a fourth axis later. This would require 42V 8A. Would the 7.2 A make that much difference?

From the little I understand of this, motor speed is a function of voltage, motor torque is a function of amperage.

[max_imum2000]

guys , guys
you only need 2/3 of the amp rated on the motors
example
3 motors 3amps each
total is 9amp, but in the real work you only need
a supply of 9x(2/3)=6amps
to be on the safe side lets say 7amps

[ger21]

guys , guys
you only need 2/3 of the amp rated on the motors

Not always. It depends on the drives. Correct with Geckos or a Xylotex, but with a board like a Stepperworld, you'll actually need 2x the rated current per motor (full current for each coil of the motors).

If I am understanding everthing that I have read in the zone I need around 32V 6A for my three motors, so I could wire two of these in series and be ok. However, I would like to be able to add a fourth axis later. This would require 42V 8A

If you're talking about steppers here, adding more motors shouldn't requie an increase in supply voltage, if the motors are all rated the same voltage. Whether you use 1 motor or 3, the required voltage would be the same.

[wolfdagon]

Ok, I was going on something that I read in another thread. Can't find it now, but basically it said that if my motors have 5.2V per phase and 1A per phase then they will actually draw double that because there are two phases, meaning that I would need 10.4v and 2A per motor. It also said that I needed to multiply that by the number of motors to get the correct power supply, meaning 31.2V 6A for three motors or 41.6V 8A for four motors.That's what I have been basing all of my numbers on.

Now then, since it seems that I (and the guy in that other thread) am wrong about this let me give you all the info.

I have three HP LaserJet III motors. They are 5.2V per phase and 1.4A per phase when used unipolar, 1.0A per phase when used bipolar. I plan on using the bipolar with PMINO's L297-8 drives at http://pminmo.com/forsale/1X279805.pdf. If I do add a fourth axis I will use the same kind of motor and drive.

So with this information, and going by what the last few replies have said then one of the 24V 7.2A power supplies would be plenty for my needs, correct? And I could get two and wire them in parallel to get 24V 14.4A and have no problem at all running four motors?

If this is the case I will probably get two of the power supplies even though I will only need one for now. Only three available SDANTONIO.

[holbieone]

if it takes 10.4 volts to drive one motor, that is the voltage the power supply should be

if there is a range on the voltage like 10 to 20 volts go with the higher voltage it will require less amps

if you have any doubts on the amps needed more will not hurt

but to high of a voltage will

[max_imum2000]

ger21
the stepperworld driver use resistors to limit current, other drivers uses PWM or chopper to limit the current
i think thats the reason this is why the motors with stepperworld driver needs full current per winding.

[ger21]

ger21
the stepperworld driver use resistors to limit current, other drivers uses PWM or chopper to limit the current
i think thats the reason this is why the motors with stepperworld driver needs full current per winding.

I know, I was just clarifying your statement.

[ger21]

Ok, I was going on something that I read in another thread. Can't find it now, but basically it said that if my motors have 5.2V per phase and 1A per phase then they will actually draw double that because there are two phases, meaning that I would need 10.4v and 2A per motor. It also said that I needed to multiply that by the number of motors to get the correct power supply, meaning 31.2V 6A for three motors or 41.6V 8A for four motors.That's what I have been basing all of my numbers on.

That is incorrect about the voltage. Ideally, you want to use as high a voltage as the drives can handle, up to 15-20x the motors rated voltage. It doesn't matter if you use 1 motor or 4, the voltage stays the same.

The current required, however, will increase as you add motors. I'd ask Phil (pminmo) how much current you need to supply each of those motors, and multiply it times the number of motors.

[pminmo]

I have three HP LaserJet III motors. They are 5.2V per phase and 1.4A per phase when used unipolar, 1.0A per phase when used bipolar. I plan on using the bipolar with PMINO's L297-8 drives at http://pminmo.com/forsale/1X279805.pdf. If I do add a fourth axis I will use the same kind of motor and drive.

So with this information, and going by what the last few replies have said then one of the 24V 7.2A power supplies would be plenty for my needs, correct? And I could get two and wire them in parallel to get 24V 14.4A and have no problem at all running four motors?

If this is the case I will probably get two of the power supplies even though I will only need one for now. Only three available SDANTONIO.

Assuming the are six wire motors I would run the bipolar half coil at the 1.4A per phase. Power supply voltage as high as possible with either a safety margin for back EMF or a shunt regulator to prevent over voltage on the L298. Simplest power supply is a 24V 10Atransformer, regulator and capacitor for roughly a 34V power supply. More than enough for your motors. http://pminmo.com/simpleps.htm Without getting into the specifics, current requirements vary, 2 phase on full step requires the most supply current, sine/cosine microstepping only roughly 71% of full step current. As the power supply voltage to coil voltage ratio goes up, the chopper duty cycle declines. Thus the requirements for a switched supply would differ from a linear supply with a beefy filter capacitor.

[wolfdagon]

Assuming the are six wire motors I would run the bipolar half coil at the 1.4A per phase.

They are six wire motors, but I'm not sure how to do that. Do I wire the motors to the driver a certain way?

Power supply voltage as high as possible with either a safety margin for back EMF or a shunt regulator to prevent over voltage on the L298.

I think you have something about the shunt regulator on your website. I'll have to go back there and take a look.

Simplest power supply is a 24V 10Atransformer, regulator and capacitor for roughly a 34V power supply. More than enough for your motors. http://pminmo.com/simpleps.htm Without getting into the specifics, current requirements vary, 2 phase on full step requires the most supply current, sine/cosine microstepping only roughly 71% of full step current. As the power supply voltage to coil voltage ratio goes up, the chopper duty cycle declines. Thus the requirements for a switched supply would differ from a linear supply with a beefy filter capacitor.

I'm afraid that most of what you said just went over my head. I think I want to run the motors half step, so does this mean that I take 71% of 1.4A to get 0.994, round up to 1A per phase? And this would mean 2A per motor? If this is the case then for three motors I would need 6A and for four motors I would need 8A, right? The supplies I am looking at are Power-One HE24-7.2-A which are 24V 7.2A. If I wire them in series this gives me 48V 7.2A. You already said that 34V would be enough so I am sure that 48v would be overkill. Would there be any adverse effect using this much voltage as long as I use a shunt regulator as you suggested above? If I am right that 4 motors would take 8A what adverse effects would the 7.2A power supply have?

Sorry if I seem to be going in circles, I just seem to be having trouble wrapping my head around this.

Kenith

[holbieone]

If I am right that 4 motors would take 8A what adverse effects would the 7.2A power supply have?

that's a good question since the motor doesn't use all the windings at once ,it uses them in step