Can I increase supply voltage on Pololu electronics

Hi

I am using a home built version of Adrain's Pololu electronics as exactly as per his schematic.

I have just completed a heated bed to Adrian's design using nichrome. The bed resistance is 1.5ohms.

It runs fine but the bed temperature maxes out at 93 degrees.

I want to try ABS and I understand I need to go hotter.

The Pololu drives state a motor voltage range of 8 - 35 V.

The 5volts for logic is supplied by a 7805.

The Mosfets are VNP14NV04 which are stated as good for 40V.

I happen to have a 24V DC power supply with a 900va transformer and a huge capacitor off an old CNC machine. It actually measures about 26 Volts.

Could I safely use this as the supply and am I right in thinking the higher bed voltage will enable me to run the bed hotter.

If 24V is too high there are a number of tappings on the transformer and it looks as if I could probably get it down to 18V.

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Regards

Ian

If you use a common ground on both supplies, you could simply use the higher voltage to drive JUST the heated bed.

Just tie the grounds together then disconnect pin 3 for the heater from the board, and connect your supply to the heater in its place.

Note: The FET switches the supply to ground, so this shouldn't cause any issues. BEWARE though that the grounds on both devices are independent, and that there isn't some sort of voltage difference between them.

Thanks

I was hoping to use just a single higher voltage supply if possible so the power supply is as small as possible. Eventually I am going to house the components under the Mendel.

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Regards

Ian

I would think that it would depend on the rated voltage of your steppers. The ones I used for the x-y-z axis (NEMA 14's) are only rated 2.7 volts, but the NEMA 17 for my extruder is rated at 10 volts. I would feel ok running my NEMA 17 at 24 volts but not sure I'd go that much on the NEMA 14's. I'm using a 12 volt supply.

... steppers are driven mainly by the current through the coils, so you can drive a 2V-Stepper with 35Volts really fine, if the current is set appropriate and the drivers are specified for the higher voltage too ...

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Viktor
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Yes, but you wouldn't be able to use a linear voltage regulator (7805) for the control electronics.

You'd need a step down switch mode, like this:

Switch mode dev supply

Might need more than 300ma though.