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      J E F F R E Y   K E R R,  L L C

 

  

 

 

 

DC Servo Motor Specifications for the PIC-SERVO SC Board
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  • Brush-type DC motor
  • TTL Compatible 2 or 3 channel incremental encoder
    (index channel optional)
  • Up to 48v winding
  • 3 amp (or less) continuous operating current

The PIC-SERVO SC Motor Control Board can be used to control DC brush-type motors equipped with TTL compatible incremental encoders. Its amplifier can be operated from 12 to 48vdc and can source up to 3 amps cont., 6 amps peak. If you select a motor which falls within these parameters, you will be able to operate at its extreme conditions. Typically, however, a motor's stall current is many times higher than its continuous rated current, and the actual operating voltages required may be less than listed winding voltage. Therefore, the PIC-SERVO SC amplifier may be used effectively with motors which have specs outside those listed. Ultimately, you will have to examine the specs for a particular motor to see if it can be used effectively for your particular application. The PIC-SERVO SC Motor Control Board can also be used with external amplifiers for applications requiring a brushless motor or requiring motors with more power than can be delivered by the PIC-SERVO SC board's integrated amplifier.   (back to top)

 

Brushless Motor Specifications for the PIC-SERVO SC 3PH Board
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  • 3-phase brushless motor with hall effect commutation sensors
                    -or-
    Brush-type DC motor
  • TTL Compatible 2 or 3 channel incremental encoder
    (index channel optional)
  • Up to 48v winding
  • 6 amp (or less) continuous operating current

The PIC-SERVO SC 3PH Motor Control Board can be used to control 3-phase brushless or brush-type DC motors equipped with TTL compatible incremental encoders. Brushless motors should be equipped with 3 TTL compatible hall-effect sensors for commutation.  The controller's amplifier can be operated from 12 to 48vdc and can source up to 6 amps cont., 7 amps peak.   If you select a motor which falls within these parameters, you will be able to operate at its extreme conditions. Typically, however, a motor's stall current is many times higher than its continuous rated current, and the actual operating voltages required may be less than listed winding voltage. Therefore, the PIC-SERVO SC 3PH amplifier may be used effectively with motors which have specs outside those listed. Ultimately, you will have to examine the specs for a particular motor to see if it can be used effectively for your particular application.  (back to top)

 

Stepper Motor Specifications for the PIC-STEP Board
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  • 2-phase bipolar stepper motor (4 lead configuration)
                    -or-
    4-phase unipolar stepper motor with 6 or 8 lead
    configuration
  • Up to 45v winding
  • 2 amp/phase (or less) operating current

The bipolar chopper drive of the PIC-STEP can drive motors designed for either bipolar or unipolar drives.  If you have a unipolar motor with 6 or 8 leads, please see the manufacturer's specifications for wiring to a bipolar drive.

The bipolar chopper drive continuously regulates the winding current so that you can use a supply voltage which is much higher than the rated winding voltage.  (For example, you could use a 24v supply with a 6v winding.)  Using a higher supply voltage will allow you to operate your motor at much higher speeds.

Stepper motors are usually sized to meet a running torque requirement at a particular speed rather than sized according to their holding torque.  For example, a 120 oz-in (holding torque) motor with a rated current of 3 amps may only provide 40 oz-in of torque at 10 rev/sec, and would only require a current of 1 amp.  If this was the limiting factor in the motor selection, the 2 amp current rating of the PIC-STEP would be more than sufficient.  Ultimately, you will have to examine the specs for your particular motor and your application requirements to see if the PIC-STEP will be compatible.  Note that you can also use the PIC-STEP with higher power external drivers.  (back to top)

 

Motor Suppliers
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We do not sell motors, but the following is a list of some quality motor suppliers:

Pittman Motors (www.pennmotion.com) - DC motors and brushless motors with encoders and gearheads

Maxon Motors (www.mpm.maxonmotor.com) - DC motors and brushless with encoders and gearheads

MicroMo (www.micromo.com) - DC motors and brushless with encoders and gearheads

Globe Motors (www.globe-motors.com) - DC motors with encoders and gearheads

SKC (Shinano Kenshi) (www.shinano.com) - Stepper Motors, DC motors and brushless motors

MCG (www.mcg-net.com) - Stepper motors, DC motors and brushless motors with encoders and gearheads

Oriental Motors (www.orientalmotor.com) - Stepper motors

Dynetic Systems (www.dynetic.com) - DC motors

Additionally, surplus motors for prototyping and testing can be found at:

Servo Systems, Inc.
Herbach & Rademan
Brigar Electronics
Electronics Goldmine
Jameco Electronics

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Choosing a Servo Motor

When choosing a servo motor, start by considering your power requirements, defined as the load torque multiplied by the speed.  This will help you pick the  nominal motor size.  From there, you can determine a reduction ratio to match the motor's speed & torque to your task.

When replacing a stepper motor with servo motor, keep in mind that the nominal torque rating of a stepper is far higher than the actual torque delivered while moving.  You should always look at the actual torque required by your task rather than the "rated" torque of your existing stepper motor.