Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 183

Circuit 160: Needle pulse generator 500 Hz
Setup information
Install the two transistors, the two resistors and the two ceramic capacitors as shown in Fig. 2.160 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 500 Hz.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.160.
Components required:
1 x 2N3904 transistor,
1 x 2N3906 transis-
tor, 1 x 10 kΩ resistor,
1 x 220 kΩ resistor,
2 x 10 nF ceramic
capacitors, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.160: Needle pulse
generator 500 Hz
185