battery simulator

Battery internal resistance simulator PCB

    This project was done for a client that wanted a way to test their equipment under various conditions of battery decay.

    This was accomplished by designing a device capable of varying the voltage output and series resistance, thus simulating the effects of battery decay.

    The main components of the device are: a dsPIC33FJ32GP204 Microchip microcontroller, a MAX15035 step-down high DC-output accuracy voltage regulator, a MAX5383 SPI DAC from Maxim, a few MOSFETS and a rotary switch

    The microcontroller is used to control the output voltage of the board and its resistance based on the position of a rotary switch. Also, the microcontroller sends the measured voltage, current and resistance over the UART interface.

    The microcontroller continually polls the state of the rotary switch and compares it against an internal table. Every value of the rotary switch has a coresponding voltage output and series resistance. The voltage output of the device is controlled by changing the output of the DAC that in its turn is connected to the reference pin of the MAX15035 voltage regulator. The series resistance value is changed by switching on and off a number of six MOSFETs


dc motor tester

DC motor tester PCB

    This project was ordered by a client who needed a way to test small power DC motors before installing them, because it was found that the manufacturer offered unusually high tolerances.

    The device is used to test the datasheet parameters for two different motor types. The test is performed to measure the average operating current or a change in current consumption during a complete rotation. This measurement is performed to detect motors that don't have the reduction gear properly working.

    The on-board microcontroller (a Microchip dsPIC33FJ32GP204) uses LEDs to signal the user that the motor has passed or failed the test. Detailed information about the motor measured characteristics is sent to the UART interface after every motor test.

    The user has the ability to the motor types and accepted tolerances through AT commands sent from a computer terminal via an RS-232 cable.