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- 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
  • # 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 with 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.

    Photos - May 1982

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

    Technical 

    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
    Circuit diagram
    Transmitter and Hand-Controller 
    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
    ML926.PDF remote control receiver
    MM3-05-transmitter-TK.Electronics.jpg

    Log

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