Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 184

Circuit 161: Needle pulse generator 2 kHz
Setup information
Install the two transistors, the two resistors and the ceramic capacitor as shown in Fig. 2.161. The nine
jumper wires come next. Last but not least 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
If everything is wired correctly, you will hear a rhythmic clicking sound coming from the Piezo element. The
refresh rate is approximately 2 kHz.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.161.
186
Components required:
1 x 2N3904 transistor,
1 x 2N3906 transis-
tor, 1 x 10 kΩ resistor,
1 x 220 kΩ resistor,
1 x 10 nF ceramic capac-
itor, 1 x Piezo element,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.161: Needle pulse
generator 2 kHz