Capacitor for Unrelated Power Supply

[chad_s]

I am planning on building a power supply to drive a 3-axis board and 3 stepper motors. I don't know a lot about electronics, but I have read enough to understand the basics. I currently plan on buying a 115VAC to 24VAC 10A transformer, 400PIV 15A bridge rectifier, and 50V 26,000uF capacitor. My question is what type of capacitor should I be looking for and where is a good place to look? I haven't found any places that have anything in this range yet. Any help greatly appreciated.

[pminmo]

http://www.surplussales.com/Capacito...-300000uF.html

http://www.cascadesurplus.com/catalo...sort/2a/page/2
(although my last experience was less than steller with Cascade, web said they had 15 in stock, ordered, the sent the other stuff said they were out, but the web still said 15)

http://www.jameco.com/webapp/wcs/sto...egoryId=203065

[whateg01]

You will need to get an electrolytic cap. You have chosen a good voltage rating. That is one area where it is always better to go bigger.

Mouser is a good place to start. Also, I have found Digikey to be a good source of electronic parts. Digikey does charge a handling fee if the minimum order is not met, but I don't remember what it is, or what the minimum order is.

Here is a link to a cap meeting your description.
http://www.mouser.com/index.cfm?hand..._pcodeid=59806

Something to remember with electronics, is to always install polarized parts oriented correctly, or risk the magic smoke filling the room. (And believe me, no matter how hard you try, you cannot get all of the magic smoke back into the part! )

Good luck. It sounds like you're off to a good start.

Dave

[chad_s]

Thanks for the advice. I will be sure to be careful. I would like to try to get a little higher amperage out of the transformer, but the best I have been able to find is the 24VAC 10A. I think the voltage is sufficient, but I would really like to get a couple more amps. I am going to be running 3A stepper motors and plan to run them at a max of 70% so I figure I need about 12.6A from the supply. Any idea where I might be able to get a transformer in this range? Or will the 10A be enough? Thanks again for the advice.

[eman5oh]

Rember that most if not all chopper style drives will only require 2/3 of a motors rated current for steppers. So 3 3 amp motor would need 6 amps.

Originally Posted by chad_s Thanks for the advice. I will be sure to be careful. I would like to try to get a little higher amperage out of the transformer, but the best I have been able to find is the 24VAC 10A. I think the voltage is sufficient, but I would really like to get a couple more amps. I am going to be running 3A stepper motors and plan to run them at a max of 70% so I figure I need about 12.6A from the supply. Any idea where I might be able to get a transformer in this range? Or will the 10A be enough? Thanks again for the advice.

[chad_s]

Yeah I had read that, but the documentation that came with the board I assembled instructed to take 2x of 70% of the rated motor amperage multiplied by the number of steppers, which in my case is 3. So that is what I have been using to size everything.

[ViperTX]

chad_s.... you could buy two transformers and parallel the outputs..

[chad_s]

Thanks for all the help everybody. I have ordered all the parts and even better I am pretty sure how to wire it all up. If not I will be back with more questions. Thanks again. Happy Holidays.

[HobbyCNC]

Originally Posted by chad_s Yeah I had read that, but the documentation that came with the board I assembled instructed to take 2x of 70% of the rated motor amperage multiplied by the number of steppers, which in my case is 3. So that is what I have been using to size everything.

You'll be fine with the 24VAC 10A tranny with 3pcs 3A steppers.

Dave Rigotti
HobbyCNC.com

[smarbaga]

you might want a small 5v and or 12vdc supply there as well for control voltages in the near future .
maybe keep that in mind before you nail everything down.