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Mechanical assembly and adjustment

view from below A look at the underside of the Photovore. Both clocks have a sprung support attached. The material is the same as used for the feelers: tinned copper wire 0,4 qmm (0.7 mm thick, 21 AWG). First use clear contact adhesive to glue the supports into folded pieces of paper, then glue the paper onto the clocks.
Feeler S0 - here in view - should be bent in such a way that it doesn't touch the copper along the edge of the print. Click on the photo for a larger version (76K).
  1. The PCB has mounting points for the feelers (marked S0 and S+ on the layout), their contacts (A) and the wires to the clocks (M1, 0, M1) and the solar panel (Z+ and Z0).
  2. Temporarily connect the clocks and the solar panel (make sure the panel's plus is connected to Z+, the minus going to Z0) and push the seconds hands onto their shafts. Adjust their rotation speed using the 5M variable resistor. Look for the highest rpm where the motors still run smoothly and positively turn clockwise. Make sure you are OK at both the high and the low voltage permitted by the power supply.
  3. Vary the voltage over the 4700uF capacitor by partly covering the solar panel (close to a window for good daylight). Adjust the switch-off level using the 250K variable resistor. The clocks should still be running well at that voltage. Just a little lower and the seconds hands will only wobble a bit. Check the rotation speed adjustment.
  4. Check the operation of eyes and feelers, by varying the light and connecting point A with S0 or S+.
  5. Does everything work really well? Then disconnect the solar panel and use a clear contact adhesive to glue the clocks onto the PCB as shown. Cut their wires to fit and solder them onto the points M1, M2 and the common 0 in between. Make sure M1 and M2 are connected to the right clocks.
  6. Take a piece of paper and draw a circle with a radius of 5 inches. Use a pencil or something like that as a former to wind the spring of a feeler. The material is tinned copper wire (0.4 qmm, 0.7 mm thick, 21 AWG). Bend the feeler itself to match a quarter of the circle. Make sure the shaft (at the other end of the spring) is bent in such a way as to put the spring near the corner of the PCB, when the shaft is soldered in place. side view
  7. When both feelers have the correct shape, you can solder them onto the print (points S0 and S+).
  8. Bend the contacts in shape and solder them onto the points A.
  9. Form the sprung supports to look like the one visible in the first picture. First use clear contact adhesive to glue the supports into folded pieces of paper, then glue the paper onto the clocks.
  10. Slide some tight-fitting heat-shrinkable tubing onto the minute hand shafts of the clocks (enough to cover them completely). Then push the wheels on the shafts.
  11. Solder two short lenghts of isolated copper wire - different colors to mark plus and minus - onto the solar panel. The connection pads (underside) look pretty solid, but I applied the soldering iron for the shortest possible time! Use just a little solder and make sure it flows. One second is enough.
  12. Stick two small bits of double-sided tape (1" x 0.5" each) onto the PCB, then push the solar panel carefully in place. Make sure the wires end up near the points Z+ and Z0 on the other side of the board. The thickness of the tape will give the soldered joints enough room - assuming you didn't use too much solder.
  13. Now solder the wires from the solar panel onto points Z+ and Z0.
  14. Put the robot on its wheels, so it can start on its way to a better place under the sun.
The `eyes' seek light well enough without adjustment, but can be confused by spots of light on the table or floor. A bit of screening may improve performance - there is room for experiments here. BPW41 with screen

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