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OT: power supply noise

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raymondj(at)frontiernet.n
Guest

Posted: Sat Apr 26, 2014 12:13 pm Post subject: OT: power supply noise

Greetings,



I'm considering putting an unregulated power supply (transformers, 

diodes, and a condenser) in an old computer box along with the 

electronics to run several stepper motors for a CNC system.



I'm wondering if noise radiated from the power supply will cause 

problems for the stepper motor drivers.



Thanks for any brilliant insight or wild ass guesses about this 

situation.:>)



do not archive



-- 

Raymond Julian

Kettle River, MN



The things we admire in men, kindness and generosity, openness, honesty, 

understanding and feeling are the concomitants of failure in our system. 

And those traits we detest, sharpness, greed, acquisitiveness, meanness, 

egotism and self-interest are the traits of success. And while men 

admire the quality of the first they love the produce of the second. 

-John Steinbeck, novelist, Nobel laureate (1902-1968)

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ceengland7(at)gmail.com
Guest

Posted: Sat Apr 26, 2014 6:13 pm Post subject: OT: power supply noise

On 4/26/2014 3:10 PM, rayj wrote:

 	  Quote: 	
		   



 Greetings,



 I'm considering putting an unregulated power supply (transformers, 

 diodes, and a condenser) in an old computer box along with the 

 electronics to run several stepper motors for a CNC system.



 I'm wondering if noise radiated from the power supply will cause 

 problems for the stepper motor drivers.



 Thanks for any brilliant insight or wild ass guesses about this 

 situation.:>)



 do not archive



If you're talking about a regular 60 hz line transformer, with properly 
	


sized capacitors after the diodes to filter out the 60 hz AC sine-wave 

ripple voltage, you should be fine.

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nuckolls.bob(at)aeroelect
Guest

Posted: Sat Apr 26, 2014 7:57 pm Post subject: OT: power supply noise

At 03:10 PM 4/26/2014, you wrote:

 	  Quote: 	
		  



Greetings,



I'm considering putting an unregulated power supply (transformers, 

diodes, and a condenser) in an old computer box along with the 

electronics to run several stepper motors for a CNC system.



I'm wondering if noise radiated from the power supply will cause 

problems for the stepper motor drivers.


	


   Probably not. Do you have these parts already in hand?

   Regulated, clean power supplies up to 350W are pretty

   cheap on eBay. I seldom build a supply any more, the labor

   alone is more than the cost of an off-the-shelf, plug-n-play

   device.



   Bob . . .

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raymondj(at)frontiernet.n
Guest

Posted: Sun Apr 27, 2014 6:57 am Post subject: OT: power supply noise

The parts were part of the CNC kit I bought years ago.  It is the power 

supply for the stepper motors.  The output is in the neighborhood of 5 

amps at 38Vdc The kit specified an UNregulated power supply because of 

problems associated with back emf from the stepper motors as they 

decelerate, as I understand it.



The motor drivers derive the required 5Vdc internally from the power 

supply hookup.



My main concern was about radiated noise being picked up because they 

are both inside an old metal computer case.



Thanks for the reply.



Raymond Julian

Kettle River, MN



The things we admire in men, kindness and generosity, openness, honesty, 

understanding and feeling are the concomitants of failure in our system. 

And those traits we detest, sharpness, greed, acquisitiveness, meanness, 

egotism and self-interest are the traits of success. And while men 

admire the quality of the first they love the produce of the second. 

-John Steinbeck, novelist, Nobel laureate (1902-1968)



On 04/26/2014 10:56 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 03:10 PM 4/26/2014, you wrote:

> 

>

> Greetings,

>

> I'm considering putting an unregulated power supply (transformers,

> diodes, and a condenser) in an old computer box along with the

> electronics to run several stepper motors for a CNC system.

>

> I'm wondering if noise radiated from the power supply will cause

> problems for the stepper motor drivers.



    Probably not. Do you have these parts already in hand?

    Regulated, clean power supplies up to 350W are pretty

    cheap on eBay. I seldom build a supply any more, the labor

    alone is more than the cost of an off-the-shelf, plug-n-play

    device.



    Bob . . .

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nuckolls.bob(at)aeroelect
Guest

Posted: Sun Apr 27, 2014 10:01 am Post subject: OT: power supply noise

At 09:56 AM 4/27/2014, you wrote:

 	  Quote: 	
		  



The parts were part of the CNC kit I bought years ago.  It is the 

power supply for the stepper motors.  The output is in the 

neighborhood of 5 amps at 38Vdc The kit specified an UNregulated 

power supply because of problems associated with back emf from the 

stepper motors as they decelerate, as I understand it.


	


   Steppers don't generate back emf based on

   motion of the moving parts. For the fastest

   possible response time, steppers like to be

   driven from high resistance if not purely constant

   current power sources. It's all about that

   t=L/R thingy.



   The first stepper systems I crafted used banks

   of power resistors to raise power source impedance.

   Modern designs will use constant current output

   stages in the drivers if they're seeking high

   accuracy positioning along with fast response.



 	  Quote: 	
		  The motor drivers derive the required 5Vdc internally from the power 

supply hookup.



My main concern was about radiated noise being picked up because 

they are both inside an old metal computer case.


	


   Your application would run quite well from unregulated,

   full wave rectified AC as long as the 'relaxed' voltage

   is not so high as to place output transistors at risk

   in their OFF state.

   Bob . . .

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raymondj(at)frontiernet.n
Guest

Posted: Sun Apr 27, 2014 10:28 am Post subject: OT: power supply noise

Thanks. Now out to the shop!



do not archive



Raymond Julian

Kettle River, MN



The things we admire in men, kindness and generosity, openness, honesty, 

understanding and feeling are the concomitants of failure in our system. 

And those traits we detest, sharpness, greed, acquisitiveness, meanness, 

egotism and self-interest are the traits of success. And while men 

admire the quality of the first they love the produce of the second. 

-John Steinbeck, novelist, Nobel laureate (1902-1968)



On 04/27/2014 01:00 PM, Robert L. Nuckolls, III wrote:

 	  Quote: 	
		   

 <nuckolls.bob(at)aeroelectric.com>



 At 09:56 AM 4/27/2014, you wrote:

> 

>

> The parts were part of the CNC kit I bought years ago.  It is the

> power supply for the stepper motors.  The output is in the

> neighborhood of 5 amps at 38Vdc The kit specified an UNregulated power

> supply because of problems associated with back emf from the stepper

> motors as they decelerate, as I understand it.



    Steppers don't generate back emf based on

    motion of the moving parts. For the fastest

    possible response time, steppers like to be

    driven from high resistance if not purely constant

    current power sources. It's all about that

    t=L/R thingy.



    The first stepper systems I crafted used banks

    of power resistors to raise power source impedance.

    Modern designs will use constant current output

    stages in the drivers if they're seeking high

    accuracy positioning along with fast response.



> The motor drivers derive the required 5Vdc internally from the power

> supply hookup.

>

> My main concern was about radiated noise being picked up because they

> are both inside an old metal computer case.



    Your application would run quite well from unregulated,

    full wave rectified AC as long as the 'relaxed' voltage

    is not so high as to place output transistors at risk

    in their OFF state.

    Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

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