Compute Value and Wattage of Current-Limiting Resistors
:Note: For L/R systems only.
:This is a basic application of Ohms Law for a series circuit.
:Your resistor must drop the difference in voltage between
:the voltage at which your stepper is rated and your supply voltage:
::Resistor voltage drop = Supply voltage - stepper rated voltage
:Applying Ohms Law, divide by the rated current to get the resistance:
::Resistor value = Resistor voltage drop / stepper current
:Finally, and very importantly, you need to know how much wattage
:you will be dissipating as heat, which your resistors must be rated to handle:
::Resistor wattage rating = Resistor voltage drop * stepper current
:For example: Steppers rated at 2.5V @ 5A, with a 26V power supply
::Resistor voltage drop = 26V - 2.5V = 23.5V
::Resistor value = 23.5V / 5A = 4.7 Ohms
::Resistor wattage rating = 23.5V * 5A = 117.5 Watts