LED DICE

INSTRUCTION SHEET

 

 

 

Price - Stock No 250 - Fast Roll

Price - Stock No 251 - Slow Roll

Price - Stock No 252 - Variable Roll

Check your kit

 

Schematic Diagram

PCB Layout

  1. Make  a visual check of the PC board for damage in transit. Look for small breaks and/or other damage to tracks.  The  copper  tracks  will have  a  green coating on the tracks. This coating should be left in place as it protects the tracks from oxidation or corrosion,  and  it  does  not inhibit  soldering in any way.  A multi-meter or Electronic Circuit Tester can be used to test continuity of the tracks.
  2. A  Circuit  Board  Holder  is useful in freeing both hands for  mounting and soldering the components.  A  spring  board  clip  can  be screwed  down  and  will hold the board securely.  Wooden blocks with a suitable groove, and able to slide (say on  two  pieces  of  dowel)  to adjust to the varying lengths of PC Board also work well.  Commercially produced  stands  are  available, with an alternative magnifying glass. (types and prices available).
  3. Mounting  the components is relatively easy.  The resistors will have to have the legs bent to match their holes, and the greencap will fit in easily - any way round.They can be soldered off as you go if you  wish.
  4. The  electrolytic  capacitor  is polarised, so look on the body to find an arrow.  This arrow points down the -ve (K) leg. Check the drawing and  put it in the right way round.  
  5. To mount the push-button switch, push the two circuit board pins into  the holes where the switch goes.  Solder them and then push the legs of the switch down between the pins.  Solder the switch to the pins.  This will give a solid mounting so the dice can be attached to its box  by  the switch through a hole, with the nut on top.  The  height  of the flange of the switch will also give a height to which the flanges of the LEDs can be adjusted  before  soldering.   The globe part of the LEDs will then push up through your box and be supported in position by the switch.  The  LEDs  are  also polarised.  Find a small flat on the flange at the base of the red dome.  This flat is at  the  -ve(K)  leg.  See  the drawing  for  the  correct  polarity of each LED. 
  6. The 8 Pin & 16 Pin I.C.  Sockets can be soldered in carefully to make sure that no bridging occurrs between legs.  You will find that the legs of both the I.Cs are spread a little wide to fit into their sockets.  Take each I.C. and rest  the  legs  on  a flat  surface.   Gently  push  down  so that row of legs is straightened a little.  Repeat for the other row of legs.  Take the 555 Timer and find the locating mark on the top surface and near or at one end.  Check the drawing and push it into its socket the right way round.  The procedure for the 4017 is similar but ,  because  it can  easily  be  destroyed by static electricity, leave it in its antistat case until you have all other components, switches, battery snap  etc. in place and soldered off.  Finally, find the locating mark on the  top  surface  of  the  4017, check its position with the drawing, and push the IC into its socket. 
  7. The dice is now ready for testing.  Connect  a  9V  battery,  switch  the slide switch "on" and push the button.  All LEDs will light up; release the button and one  will  stay on. ( This is a purely random selection so there is no way to "rig" the dice). 
  8. If  you  want to experiment,try putting preferably sweaty fingers at various places on the soldered joints with the slide switch turned  on.   In  some  cases  the  lights  will "roll" on in sequence, slowly.  This indicates that changes to capacitance values and/or  resistance  values will achieve a similar result. 

MORE INFORMATION

View the Datasheet for the 4017.

View the Datasheet for the 555.

 

TROUBLESHOOTING

If  the dice doesn't work then you will need to check all polarities  and ensure that all components are in correct places.  Check  soldering  and resolder any suspect joints.

TECHNICAL NOTES

It will help if a general understanding of the circuit is acquired.  Briefly , when the PB switch is depressed a pulse is generated by  the  555 IC  (Timer).  This pulse is conducted to the 4017 IC (Decade Counter) which acts as a rotary switch.  In this case only six of the IC's pins  are  used to  distribute  the  pulse  to  the LEDs in turn.  The next pin in order is connected to the reset pin of the IC.  This restarts the  switching  action to maintain an automatically resetting switching process.  This all happens very quickly, so fast that all LEDs appear to light up when the push button is pressed. The  system equates roughly with the spark distribution system of a motor car engine , where the pulse at  the  distributor  points  (or  their substitute)  generates a high voltage at the coil , which is distributed to the spark plugs by the rotor  in  the  distributor  -  a  rotary  switching mechanism.         The alpha-numeric grid locations on the placement sheet are used in this guide.

Contact CdS electronics

Home Page