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  #1  
Old Wed 06 January 2010, 04:12
saas
Just call me: saas
 
ceje
Slovenia
I need some help with procurement of power sources?

I purchased TOROID 300VA 25V +25 V!

Me interested in whether to buy?
PMDX 135, 50 volt, 20 Amp or
PMDX 136, 50 volt, 10 Amp
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  #2  
Old Wed 06 January 2010, 05:17
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Sasa,

Since you bought a 300VA at 2x25V power source, then means your transformers maximum output current is :
p=u*i i=p/u i=300VA/25v i=12Amp

You would be better of with the PMDX-135

if you are looking into ways to save money and want to by the PMDX-136 then the consequences are:
- More voltage ripple (more buzz so the speak) from the power supply at high currents.
- Since it was designed for 10Amp, you might fire (as in real fire) something during long time high power usages.

Ries
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  #3  
Old Wed 06 January 2010, 08:19
saas
Just call me: saas
 
ceje
Slovenia
Aha-ahaaa

Yes, the motive was saving money,

.. Money, money, money
Always Sunny
In the rich man's world
Aha-ahaaa
All the things I could do ..
www.youtube.com/watch?v=E5RSrNFj_is

Excuse my stupidity to

Thank you Ries
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  #4  
Old Wed 06 January 2010, 08:21
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Ries, I think that might be 300VA/50v=6A.
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  #5  
Old Wed 06 January 2010, 08:58
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Heath,

I was thinking that it was a power supply 50V out, 2x 25V, much like this configuration : http://www.antekinc.com/pdf/AN-3225.pdf

Since his he mentioned the PMDX 135/136 at 50V you cannot run this transformer in series with the mentioned products, only parallel: sqrt(2)*25=35.4V (below 50V)
giving it a maximum current of 12A

Now, if Sasa is planning to run the transformer in series at 50V (sqrt82)*50=70Vdc (not below 50V) then he would still need the PMDX 135-8020 because that is actually a 80V/20A PMDX-135

If Sasa want's the run the transformer in parallel he needs to buy : PMDX 135 - 5020 or PMDX 135 - 8020
If Sasa want's the run the transformer in series he must buy : PMDX 135 - 8020

The PMDX 136 would not work because in series it's to much voltage for the PMDX 136, and in parallel it's to much current for the PMDX 136

Ries

Last edited by riesvantwisk; Wed 06 January 2010 at 09:04.. Reason: Correction on PMDX series
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  #6  
Old Wed 06 January 2010, 10:23
domino11
Just call me: Heath
 
Cornwall, Ontario
Canada
Ries,
Sorry for the confusion, I was fixated on the 50V part. Your last post sums it up nicely.
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  #7  
Old Mon 11 January 2010, 03:50
saas
Just call me: saas
 
ceje
Slovenia
now I'm a little confused

parallel or serial connection TOROID Transformer?
variant of the capacitor + diode PMDX or 135( 80V or 50 V)? or

I have no experience, and I have the possibility of all varieties ....
what to choose?
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  #8  
Old Mon 11 January 2010, 05:40
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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Saas,

that depends what stepper motors you are planning to use.
Which stepper motors did you buy?

Ries
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  #9  
Old Mon 11 January 2010, 09:44
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
why spend $100+ on these boards when 1x bridge rectifier + enough capacitance (based on needs) will do the job as good?



Stepper motors just need this, more is better, fancier but not really needed IMHO

But, I understand if someone is not versed in soldering and want to go the off the shelf route


Pablo
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  #10  
Old Mon 11 January 2010, 13:27
saas
Just call me: saas
 
ceje
Slovenia
Pablo,

Price two capacitors is about 106 $ + bridge rectifier about $ 5
Price PMDX 135 is (106$ - 50V) or (119 $ - 80V)
I certainly buy PMDX 122, therefore, includes postage and PMDX 135th ..... , OK?

Me interests what is better?

Many thanks Ries ,
I'll try to get PK296AE-SG7.2 or MotionKing 34HS9801, now I would’t have to study anyway
I believe Gerald_D!
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  #11  
Old Mon 11 January 2010, 14:01
PEU
Just call me: Pablo
 
Buenos Aires
Argentina
10000uF x80v caps are $16.60 here in Argentina in the 1st place I looked for them, Im sure I can trim an extra dollar or two if I look further. I would recomend to search for other providers, $53 seems to be pretty expensive. If thats your only choice, well then, I agree with you, the PMDX option seems a good one.
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  #12  
Old Tue 12 January 2010, 06:17
riesvantwisk
Just call me: Ries #46
 
Quito
Ecuador
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@Sase,

Out of your power supply you wuill have :
At 25Vac you will have a DC voltage of 25V*sqrt(2)=35Vdc
At 50Vac you will have a DC voltage of 50V*sqrt(2)=70Vdc

if my calculations are right, then with this power supply your only option is to buy Stepper PK296AE-SG7.2.

Let's to the math:
The 34HS9801 are 4.1mh unipolair, which makes maximum voltage for these stepper: sqrt(4.1)*32=64V, no good for your power supply because 35Vdc is not enough, 70Vdc is to much.

The steppers PK296AE-SG7.2 are 1.5mh unipolair = sqrt(1.5)*32=39V This seems to be just nice for 35Vdc.

Sase, I am not familiar with the PK296AE-SG7.2 stepper but I think people use them unipolar here so with your bought power supply that seems to be the only option.

Ries
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