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2.66 Simple AM-Radio
Circuit 141: Simple AM-Radio
Setup information
Install the three transistors, the four resistors, the three ceramic capacitors, the fixed value inductor and the
two electrolytic capacitors as shown in Fig. 2.141. Then insert the 20 jumper wires. Last but not least, con-
nect 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
This circuit is a simple yet responsive and selective AM receiver for MW. If you have, use a small variable
capacitor (about 200 pF) from your crafting box for C1. If you don't have one, experiment with the ceramic
capacitors of the experiment box (10 pF, 100 pF, 220 pF). One of the many possible different parallel/series
combinations will almost certainly establish a good radio reception. The best reception conditions are at
night when you can also receive stations from southern Europe. Germany and Austria have no AM broad-
casting station any more.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.141.
Components required:
2 x 2N3904 transistors,
1 x 2N3906 transistor,
1 x 1 kΩ resistor,
1 x 2.2 kΩ resistor,
1 x 470 kΩ resistor,
1 x 1 MΩ resistor,
1 x 220 μH fixed induct-
ance, 2 x 100 nF ceramic
capacitors, 1 x ceramic
capacitor (see Experiment
for value), 1 x 1 μF electro-
lytic capacitor,
1 x 10 μF electrolytic capaci-
tor, 1 x Piezo element,
1 x breadboard, 1 x 9V bat-
tery with clip connector
Fig. 2.141: Simple AM-Radio
167
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