I am hoping someone on Ice In Space can help with a question to run a uni-polar stepper motor. The motor is 12VDC 3 Watts which would take 250mA. I would need to use limiting current resistors that 250mA is all that can be drawn by the motor. Some circuits I've seen have a formulae to use R (resistance in ohms) = Voltage of motor minus rated winding voltage (four windings) / Rated winding current. I guess the resistor to use would be 24 ohms at 3 watts each, would that be correct??
Can I join the two supplies as seen at the top of the circuit in red to use the one source for the 5 Volt regulator and the 12V to supply the motor.
Yes, you can join those power supplies together... however do not connect more than 30V, as this is the voltage limit for IC1.
You do not need resistors if you use 12V.... because 24ohm is the internal resistance of the motor winding.
However, if you use higher voltage, then for every volt above 12V you should use 4ohms... or thereabouts.
For example, if you have 15V, this is 3V above 12, your resistor should be 3V/250mA = 12ohms.
Yes, you can join those power supplies together... however do not connect more than 30V, as this is the voltage limit for IC1.
You do not need resistors if you use 12V.... because 24ohm is the internal resistance of the motor winding.
However, if you use higher voltage, then for every volt above 12V you should use 4ohms... or thereabouts.
For example, if you have 15V, this is 3V above 12, your resistor should be 3V/250mA = 12ohms.
You can also ignore the center taps and connect a bipolar driver to the ends of the coils. Some unipolar stepper wires have 8 wires because the coils are separated In this case you have to join the coils to make them behave like a bipolar motor. Then you can use one of the popular bipolar drives such as the Stepstick or Easydriver.
A small, little question? Do I let the pins 1, 2 & 3 float connected to nothing or do I connect it to ground. All the other pins are connected to other parts of a circuit, but I am curious what do I do with pins that I am not using? Using a 4093 CMOS IC. The chip is part of a stepper motor circuit I am using.
Last edited by imhimmelkommter; 07-03-2017 at 09:59 PM.
Reason: grammar
