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Building the robot

The Photovore is not at all complex. If you have some experience using a soldering iron, you can build it in two or three hours. But I would not recommend it as a first project for beginners.

PC board assembly

Those who found the parts for the robot elsewhere, need to make their own printed circuit board. A scan of the film should make that fairly easy. If you bought the kit, you already have a print. You'll only need to saw off the excess material. Do sand the edges for a neat result.

Photovore print

The components are soldered onto the copper-side of the print, as if they were surface-mounted devices. That way the topside stays smooth, giving a better appearance and offering a good surface for mounting the solar panel. The circuit area will gather less dust and dirt, making the robot more reliable. But you do need to mount the components in a sensible order - otherwise the soldering iron will at some point damage previous components when you try to add the next one.
The IC's can best be soldered in place. Use a temperature-controlled soldering iron, or if that is not available, a small one of less than 16 watts.

shape of the leads Prepare the components for surface-mounting by first cutting the leads to the right length. Bending the ends as shown makes for better joints.

The layout below shows where each component belongs. Click on the photo above for a close-up (59K) of the finished board. BTW: The fiber-enforced epoxy carrier is dark green, not red. It wasn't my scanner that introduced the wrong color. The (chemical) photo shows it too. I have no idea what caused this. The other colors are fine...


I mounted the components in this sequence:

  1. The isolated wire below the 74HC00 in the middle.
  2. The two 74HC00's (careful: don't heat any of the pins longer than about a second)
  3. The BC549C
  4. The 5M variable resistor
  5. The 100N capacitor
  6. The three 100K resistors
  7. The two 470K resistors
  8. The two BC559C's
  9. The green LED
  10. The 150E resistor
  11. The 250K variable resistor
  12. The two diodes (1N4148)
  13. The two photodiodes (BPW 41)
  14. The two 47uF capacitors
  15. The 100uF capacitor
  16. The 1M resistor
  17. The 10M resistor
  18. The 2M2 resistor
  19. The 4700uF capacitor

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