Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 217

Circuit 194: Simple IR receiver
Setup information
Install the transistor, the resistor and the electrolytic capacitor as shown in Fig. 2.194 followed by the
jumper wire. Finally connect the Piezo element. Check the placement on the board again and only then
connect the battery.
You can significantly increase the sensitivity of the Piezo element by using a sound plate or even a sound
box. Read more about it in Chap. 1.2.3
Experiment
You can connect an mp3 player or the speaker output of a portable radio to the input. IR diode and pho-
totransistor must face each other head-on at a distance of up to a few centimetres. You will hear music
coming from the Piezo element. If you hold a small piece of metal sheet or cardboard between the IR diode
and the phototransistor, transmission stops immediately.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.194.
Components required:
1 x PT331C phototransis-
tor, 1 x 10 kΩ resistor,
1 x 10 μF electrolytic
capacitor, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.194: Simple IR receiver
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