Would really appreciate some help on my little project. I have acquired a dual shaft stepper motor connected at both ends to pump heads. This item is surplus and is designed to dispense minute ammount of liquids. The flow rate according to the mfg is 50ul per revolution (200 steps).
I need to find/build a controller that can control the stepper motor by rotating it in the neighbourhood of 1.5 to 20 rpm to dispense the required amount of liquid.
The stepper motor is a PowerMax II Model #P21NSXS-LSS-NS-04. It is a special OEM model, but from another CNCZone thread it appears the specs of the motor is as follows.
All you need to complete your application is a variable frequency 5 volt square wave generator, a 5 volt logic supply, and a stepping motor controller with power supply.
The variable frequency generator will need to be adjustable over the range of 100 Hz to 5000 Hz. This frequency can be controlled by a variable potentiometer. The output from this unit would be connected to the step input on the stepping motor controller. (If more control is needed such as micro-stepping of the motor, then a micro-stepping drive is required, and the square wave generator will have to have an increased frequency range to accomodate the increased number of pulses for micro-stepping.)
The direction or rotation of the pump/motor combination would be controlled by a logic level of 5 volts or 0 volts to the direction pin of the controller. This could be accomplished by a single pole double throw switch with the common connection of the switch made to the controller and one side of the switch made to 5 volts and the other side to 0 volts. Flipping switch changes direction.
The stepping motor controller can be purchased in kit form. You will have to verify that whatever controller you use can handle the stepper motor current which I believe is 1.5 Amps. One will also have to limit the max current to the 1.5 Amp value. I would recommend a 24 Vdc power supply for the controller.
There are several suppliers of these kits which advertise here on CNCZone. You can also do an internet search for Stepping Motor Kits.
PowerMax II Stepper Help
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