home  >  Quester < MM3 > Zeaker 16 July 2023
- Circuit diagram  |  Transmitter and Hand-Controller  |  First drawing  |  ZX81 program  |  Gallery 1982  |  Gallery 2021
M23 by David Buckley May 1982
M23 - Retired
Computer controlled Turtle using an Infra Red communications link.
Won a Bronze Medal at the 1988 International Model Engineer Exhibition, London.
Photograph - Scale Models International, April 1988, p207.
Built May 1982.
Size - 10" * 10" * 5".
Operational area - minimum 4ft * 4ft plus host computer.
Built to be controlled over an Infra-Red (IR) link from a Sinclair ZX-81 or a Compukit UK101.
M23 or MM3 stands for Micro Machine 3. It was the third robot vehicle I made.[1]

  • # Photos
  • # Technical information
  • # Arduino software
  • # Upgrade Log

  • Circuit diagram
  • Transmitter and Hand-Controller
  • First drawing
  • ZX81 program
  • Gallery 1982 photos
  • Gallery 2021 photos
  • The ZX-81 program allowed the user to type in a series of commands in up to ten separate routines called macros and then to type in a list of up to ten names in a list of macros to be executed.
    The tower at the rear houses the IR detector, the decoder, diode-logic plus motor-control-relays are on a circuit board in the body.
    Round the perimeter to detect contact with obstacles are eight Sensor plates with switches behind, the intention was to send the Sensor information to the controlling computer.
    The Arm in the centre carried a pen to draw Logo style Turtle graphics and the complete pen-unit was detachable, the signals and power being routed through the 16-way DIL socket and plug just behind the box, containing the motor, which is marked RI. While at an exhibition someone stuck an Atari sticker on MM3, probably because it was running off a ZX-81 at the time. So I cut up the sticker to make the RI and rainbow.
    On the other side the 16-way DIL socket carrys the signals from the Sensor plates and signals from the IR decoder to the motor relays. The socket is wired to allow signals from the socket to over-ride the IR-decoder. The intention was to mount a small computer in the spare space to starboard of the pen and have it do local control.
    The IR sender (not shown), besides having a socket for signals from the controlling computer, also has a set of buttons for manual control. Using the buttons proved much more fun!
    At 2007 MM3 still exists and with the odd drop of WD40 in various places, especially the pen mechanism limit switches (replaced in 2011), will still perform. One day I might even de-retire (detire?) it and put on a 'Stamp' for local control.
    In 2023 I added an Aduino interface which gives computer control again - see below

    Photos - May 1982

    The middle photo shows the hacked TK Electronics IR receiver kit powered by two 9v batteries.
    The prototype transmitter electronics.


    MM3 Control Codes
    0000  0  rest state, default code
    0001  1  PU             Pen Down   
    0010  2  PD             Pen Up
    0011  3  LEDs off
    0100  4  RLED           Right LED on
    0101  5  LLED           Left  LED on
    0110  6  Buzz off
    0111  7  Buzz
    1000  8  FD	LF,RF   Forward
    1001  9  BK     LB,RB   Backward
    1010 10  RL     LB,RF   Rotate Left
    1011 11  RR     LF,RB   Rotate Right
    1100 12  CBR    LB,--   Curve Backward Right
    1101 13  CFR    LF,--   Curve Forward Right
    1110 14  CBL    --,RB   Curve Backward Left
    1111 15  CFL    --,RF   Curve Forward Left
    Codes diode decoded in MM3
    Controller Keys
    Horn On    Left LED On         LEDs Off      Right LED On 
    Horn Off   Curve Foward Left   Forward       Curve Foward Right
    Pen Up     Left Turn           Enable Keys   Right Turn
    Pen Down   Curve Back Left     Back          Curve Back Right
    Battery On
    Drive Motor Circuit jpg
    Pen Servo circuit jpg
    SL490.pdf remote control transmitter
    SL480.pdf Infra-red preamp
    ML926.PDF remote control receiver
    Concept drawing MM3-01.jpg

    Arduino software
    Allows MM3 to be controlled by the above commands either direct from a keyboard or saved in sixteen Acts in EEPROM. It also allows control by Heading, and navigation on an XY grid to grid-coordinates or named places. The Curve commands are not currently incorporated into XY navigation.


    [1] - 'Micro Machine 3' was suggested by Steven John, a work collegue.
    home   -   top