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Nashua Robot Builders (NRB) Newsletter

November 1997

The NRB meet the second Saturday of each month at Cyber Joe's

Internet Cafe in Nashua. Meetings start at 1pm.
You can find our web page at:


In this issue:

   Servo Hacking with Jim Shepherd
   Robot Showcase
   Next Month's Topics

  Servo Hacking with Jim Shepherd:


This month, Jim gave us a tutorial on how to convert a standard hobby servo into a gearhead     equipped motor. Jim started hacking servos when he put together the Micromouse kit from Lynxmotion.. The kit came with very detailed information on servos, as well as clearly written and illustrated instructions on how to perform the modifications.


While we watched, Jim disassembled a new servo. The basic steps (without the details) are : remove and modify the feedback potentiometer so that the servo can rotate 360 degrees; bring out the wires that connected to the feedback potentiometer and add an external potentiometer; reassemble the servo and adjust the external potentiometer so that the servo does not rotate when provided with a 1.5ms pulse.


Jim used a "Servo Driver Ciruit" created by Ahmet Onat to make his trim adjustment and to test the final operation of the servo. The final result is a gearhead motor assembly that contains the motor, gears, and driver electronics. By providing a 1ms to 2ms pulse, the motor will operate proportionally from full on in one direction to stop to full on in the opposite direction. Control signals can easily be generated from most microcontrollers, or you can use a Serial Servo Controller that interfaces multiple servos to controller via a serial port.

   Thanks Jim for your great talk!

                                               Resources :
                                           Hobbico CS-51 Servo
                                           RC Buyers Warehouse
                                           95 Northeastern Blvd
                                             Nashua, NH 03062
                                             (603) 595-2494

         Robot Kits, Counterfeit Stamps, Serial Servo Controllers

  Robot Showcase:

   People have been hard at work in their "robot labs". Here are the pictures and short descriptions of member's robots that attended the meeting.

     Matt Cross' robot uses the Tamiya treaded platform (available from MondoTronics,, with his home brew 68HC11 processor and relay based motor controller.


 Jim Shepherd has heavily modified the original Lynxmotion Micromouse ( by adding his own bump sensors and the line tracking hardware. Jim's robot uses the Counterfeit Stamp included with the Micromouse kit.


At his first NRB club meeting, Ben Wirz became the proud owner of a 1980's vintage toy robot base. By his second club meeting, he added a power supply and controller, multiple PIC SimmStick(TM) and MiniBus boards, two industrial surplus infrared proximity sensors, and Polaroid sonar modules.


Next Month's Topics:

   Ben Wirz will be talking about PIC microcontrollers, and giving a demo on various PIC related development hardware and software. Ben's company, Wirz Electronics markets a number of different PIC related products, including the DonTronic's PIC SimmStick(TM) and MiniBus used in Ben's current robot project.

PIC SimmStick(TM)


We'll also be talking about contests!! Bring your ideas to the meeting and let's hash out something to get everyone building 'bots.


   Chris Burian *New Member*
   Matt Cross
   Jay Francis
   Jim Shepherd
   Ken Wilkens
   Ken Williams
   Ben Wirz

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