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Why is RUMBA rated at35v?

Posted by Tom Brown 
Why is RUMBA rated at35v?
May 20, 2013 07:27PM
It seems like all of the affordable PSUs are 36v.
Re: Why is RUMBA rated at35v?
May 20, 2013 07:33PM
It probably uses a 4988 driver chip or similar and they are rated from 8-35V.
Most of the Chinese sourced switching mode PSU's have trim pots that let you adjust the voltage by about 2V in either direction.


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Re: Why is RUMBA rated at35v?
May 20, 2013 08:57PM
Thanks! That's perfect.
Re: Why is RUMBA rated at35v?
May 20, 2013 10:49PM
Be careful those are absolute limits, likely by the drivers chip themselves. Voltage along the rails often spikes by a few volts as the fly back voltage cannot be completely absorbed. I would not go above 24v for those tiny 4988 chips. The design is ok for reprap but not precise enough to handle the extreme hairy edge of the spec.

also these voltage limits are acompanied by reverse internal diodes to handle electrostatic charge. if these diodes blow, your chipset likely will in a short time as well! (this is different than the fly back diodes that absorb and in many cases return voltage back to capacitors.)

Edited 1 time(s). Last edit at 05/20/2013 10:51PM by jamesdanielv.
Re: Why is RUMBA rated at35v?
May 20, 2013 11:19PM
Why do you want so much voltage??????

I would stick to 12 volts unless you need the higher voltage for something else. Most hotends are rated for 12 volts unless you have one made for 24. Most heatbeds and these driver work very well on 12 volts.

I use these 30 amps, 12 volt power supplies for mine and the price is super

[www.ebay.com]

Rodney
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