(Shock Absorber Tester) P16221 Damper Dynamometer (Shock Absorber Tester) The Sparkfun logic level shifter protects the digital inputs of the microcontroller from the harmful voltages of the serial port and motor controller. Protection from static electricity is provided by the Vishay CNY17-3 optoisolator and the Texas Instruments ISO124P analog isolator. Static electricity can produce voltages in the tens of thousands of volts. These devices keep the microcontroller safe. The Texense INFKL-150 infrared temperature sensor measures the temperature of the damper from a distance of 2 in. (50 mm) away. In order to get accurate measurements the damper must be at a stable temperature. The temperature sensor can measure up to 302° F (150° C). The PCB Piezotronics 1403-14A/084A100 load cell measures the forces on the damper. It can measure up to 2,500 lbf. (11,120 N) of push or pull force on the damper. The Arduino Due is the heart of the dyno. It monitors all of the sensors, communicates with the user PC and controls the motor used to operate the damper at fixed speeds for measurements. It uses the 32-bit Atmel ATSAM3X8E ARM Cortex 3 microprocessor operating at 84 MHz. It has 54 digital I/O pins, 12 analog input pins, and 2 digital to analog converters. This microprocessor has the power and speed to monitor and control this sophisticated piece of equipment. The PC user interface is written in Microsoft Visual C#. The Active Sensors MLS-3 linear potentiometer is used to measure the length of the damper at any time during the test. The shaft speed of the damper is measured by subtracting two successive measurements and dividing by the time between them. The SunFounder switch hall sensor module sends motor speed signals back to the motor controller so that it can maintain a constant speed. The Allen-Bradley PowerFlex 532 motor controller is controlled by the microcontroller. The microcontroller commands the motor controller to start or stop using a digital output, and to run at specific speeds using an analog output to set the run speed the motor. The motor controller sends variable AC frequencies to the motor to change it’s speed. The motor and controller operate on 208-volt, 3-phase AC power. The Nord SK372.1 three-horsepower gear motor actuates the damper. It has a gear reduction of 4.66:1 so that the motor is capable of delivering up to 1,500 lbf. (6,672 N) of force to the damper in both compression (push force) and rebound (pull force). The speed of the motor controls the speed of the damper shaft as it is tested.