Voltage regulator in DC motor driver 1.1 - needed?

(Possibly a stupid question, I'm new here...)

Why is the voltage regulator in the DC Motor Driver 1.1 [www.reprap.org] needed? If it just converts 12 volts to 5, why not just use the +5 volt wire from the PC power supply?

-Joe McKenzie

1) easier for battery powered rigs (think solar)
2) much better noise rejection when the regulator is onboard, rather than at the other end of a bunch of wires running close to other wires carrying motor currents

yeah, originally the 1.0 used 5V from the power supply.

adrian made me add the regulator. he's got crazy plans to take over the world and that includes running all the electronics off one 12V power supply. think car battery or solar.

the component is only like $0.10 and does add some nifty features like triffid pointed out.

Cool I am on the same plan to take over the world and I thought I was Crazy!!

Bruce

But then you lose almost 60% of the power to heat with a linear regulator. it seems like you might be better off with a single efficient switching supply for 5V if you are powering it from a battery or solar. Though, whether it is worth it or not will depend on how much power the lower voltage stuff is pulling, if we run all the logic at 3.3V and have an efficient switcher, that could cut down on power perhaps.

Though, perhaps worrying about this is rather silly compared to the power requirements of the heater/motors.

The load on the 5V rail is so small that the power loss with a linear regulator is negligable. Especially compared to the power used by the motors and heater.

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[www.hydraraptor.blogspot.com]

A switcher would be nice, but they're usually require more parts and you have the possibility of adding noise if you don't have the outputs filtered. Nophead's also right in that the power pull is so small that it won't be missed. I'd guess about 50mA at 5V for the logic going up hill with a headwind.

would it be difficult to change the board to 12volts if I were to use a 12volt motor with this board?
Would it be as easy as removing the voltage regulator?

Thanks

the board already is 12v. the voltage regulator converts 12v => 5v for the signal-level voltage. the motor supply voltage uses the 12v directly. (or whatever voltage you supply to that pin.)