Resistors!! How hot?

[southernexplore]

I just built the descrete unipolar driver and was wondering this about current
limiting resistors. How hot are they suppose to get? Where you just barly can touch them, grab and hold them for a couple seconds or hold indefinitly?

Thanks,
southernexplorer

[One of Many]

Originally Posted by southernexplore I just built the descrete unipolar driver and was wondering this about current limiting resistors. How hot are they suppose to get? Where you just barly can touch them, grab and hold them for a couple seconds or hold indefinitly? Thanks, southernexplorer

Resistor packages are rated in watts, not whether they can be touched. Running them close to their limit will eventually cause failure. Keeping them away from caps(to prevent the cap from suffering too) and the board helps the heat to dissipate better.

P=ExI
P=E squared/R
P=I squared/R

P=Watts
E= voltage drop across the resistor
I=E(the voltage drop across the resistor) / Ohms of the resistor

DC

[southernexplore]

I recalculated and was using the wrong wattage resistor. I will try the higher wattage tomorrow and do some more testing with the software. I'm just trying to make a decision on which software to purchase. Mach3 has my attention though. What can I expect from this software?

Thanks,
southernexplorer

[pminmo]

One of the problems with a non chopped board is the power resistors. And you need a power supply voltage as high as the board components will allow. That means bigger resistors in the simplest term.

[ger21]

Originally Posted by southernexplore Mach3 has my attention though. What can I expect from this software?

Free upgrades for ever, the best possible support, and features added at an unbelievable rate. And it should be able to do anything you ask of it, although some VB knowledge may be required for advanced things, like toolchangers and such.