There is no information given on the Staughton family's website, regarding the connection of the infra-red LEDs, other than two 150 ohm 0.6 watt resistors being required.
The LEDs should be wired in two banks; each bank consists of two LEDs and a 270 ohm 0.6 watt resistor, all wired in series. This allows a current of aproximately 33 milliamps to flow through the LEDs. Using the SFH487 diodes specified, this gives ample illumination of the box. The Staughton boxes may have had two 150 ohm resistors in series, instead of the single 270 ohm resistor. Note that other, less efficient, LED's may not give sufficient illumination, and that the sensitivity of the ccd devices used in the cameras, may vary considerably.
The polarity of the SFH487 device is opposite to the normal LED polarity. The short lead, which is adjacent to the flat on the body, is the anode, which should be wired via the resistor to the positive of the supply.
Note the ventilation holes in each side of the plastic box. There is a considerable amount of heat generated by the camera, LEDs and resistors, which may result in unnecessarily high temperatures of some of the components. These ventilation holes will hopefully keep the components at an acceptable temperature.
The mounting holes in the cameras are rather small; too small for the M3 screws specified. On no account try to enlarge them as there are very small components on the pcb close to the holes. I used long 8BA screws and nuts, but these are difficult to obtain. Be very careful not to damage any of the components when fixing the camera into the box.
Page created 20 May 2001. Last modified 21 May 2001.