PSU : prices and differences

**Gytis** · 24-08-2013

Thank you guys,

if you are using it for steppers

Yes Clive, I need it for the 4 steppers at 3.5A

a toroidal transformer might suit your needs better

Any link for the toroidal transformers?

Thanks
Gytis

**Clive S** · 24-08-2013

Originally Posted by Gytis

Thank you guys,

Yes Clive, I need it for the 4 steppers at 3.5A

Any link for the toroidal transformers?

Thanks
Gytis

Well you could use something like this :- PS806-5 Linear power supply. or build one. it depends somewhat on the drive you will be using ...Clive

**JAZZCNC** · 24-08-2013

Hi Gytis,

You'll be much better with Unregulated supply so I'd go with toroid and build your own has the linked one doesn't provide enough currant. For 4 * 3.5A steppers You'll need minimum 8A and that only provides 6A.
It's not difficult and if you want to take that route then email me about it and I'll explain what's needed and were to buy components. Won't reply for a couple of days thou has I'm away from home at moment.

Dean.

**Gytis** · 24-08-2013

Originally Posted by JAZZCNC

Hi Gytis,

You'll be much better with Unregulated supply so I'd go with toroid and build your own has the linked one doesn't provide enough currant. For 4 * 3.5A steppers You'll need minimum 8A and that only provides 6A.
It's not difficult and if you want to take that route then email me about it and I'll explain what's needed and were to buy components. Won't reply for a couple of days thou has I'm away from home at moment.

Hi Dean and Thank you!

I'm a little bit confused right now..,
I have Gecko G540, and I decided to use these motors from cncrouterparts
so if you think that the toroidal transformers suit them better, then I'll go with your suggested route

Thank you
Gytis

**JAZZCNC** · 25-08-2013

Originally Posted by Gytis

Hi Dean and Thank you!

I'm a little bit confused right now..,
I have Gecko G540, and I decided to use these motors from cncrouterparts
so if you think that the toroidal transformers suit them better, then I'll go with your suggested route

Thank you
Gytis

Ok no need to be confused buddy it's nothing special or difficult to get your head around. I'll explain for the sake of others thou it's all on the forum somewhere else.!

You have G540 which is limited to maximum 50Vdc and provides 3.5A for the motors. Now the Voltage is Fixed and you can't use higher than 50Vdc else you'll damage the G540, in real use you shouldn't actually run at 50Vdc has Steppers are like dynamo's and produce electricity when decelerating, some of this then gets passed back to the drives and if your running at the drives maximum it can easily push the voltage past drives threshold and blow it up.!!

Now the reason why Unregulated and toroidal PSU are better for steppers and much preferred to linear regulated PSU's is because when this excess electricity is produced some of it gets passed back to the PSU. Regulated PSU's tend to be very sensitive to this and have protection built in which trips the PSU and saves it's components. When this happens that's not the end and Electricity still needs to go somewhere so back it goes to Drives which can't handle it and either trip out if protected or BOOM.!! in less capable drives.!!

Now we can't have this has steppers are constantly doing this, esp under hard deceleration from higher speeds. So with Linear regulated PSU we need larger safety margin for the drives so instead of 50Vdc you'll want to run at 40-44Vdc maximum for safety sake.
Now with steppers Voltage makes a big difference to speed and torque you'll get from them so really we don't to waste any if we want peak performance..!!. . . . . Unregulated Toroidal supply works different and it's capacitors act like sponges so easily handle any returning electricity (provided enough spare capacitance is built in.!)
Now Because of these caps sucking up excess juice it also means we can use voltages very close to the Drives Maximum and 48Vdc could safely be used.
They also mean we don't need has high Amp supply because the capacitors hold a reserve of power and because the drives will only pull power during the PWM ON cycle there's plenty juice in reserve so less amps are required for several motors. Roughly 60-70% less. So for your 4 x 3.5A maximum requirements you'll only need Approx 8A not 14A you would with Regulated supply.

One other thing you or others may not know about the G540.? It's not limited to 3.5A motors.?
It can be used with higher currant motors but the drive will only provide 3.5A so you'll get reduced Torque than motors rating. On top of this you'll lose the auto currant reduction the gecko provides when motors are at rest. (There is a easy trick to get this back thou which involves using a resistor.?)

Get in touch if you want to build one.!!