Hardware Reference
In-Depth Information
Figure 17-2:
IR SFH484-2 IR
LED emitter
wiring.
Wiring Up the Detector
he detector is made from a phototransistor, which allows current to low when light falls on
it. It must be connected the correct way around, or it may be damaged, and it should also
have a resistor in series to limit the current. Phototransistors have pins labelled
emitter
and
collector.
When illuminated, current lows into the collector and out of the emitter.
Take care to identify the legs of the phototransistors. Lay the lat side of the phototransistor
on your desk, with its legs facing you. he leg on the left is the emitter, and the leg on the
right the collector (see Figure 17-3). If you are not using a QSE113 phototransistor, check
the data sheet for your device.
