Whistle Buoy - Maker Factory ELECTRONICS EXPERIMENTS BOX Manual

2.46 Whistle buoy

Circuit 105: Whistle buoy
Setup information
Install the two transistors, the five resistors, the ceramic capacitor and the electrolytic capacitor as shown in
Fig. 2.105.The ten jumper wires come next. Finally, insert one end of the jumper wire, which will function
as switch (shown dashed) and is labelled with Start. 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
A whistle buoy is used to produce a loud and prominent warning signal. Our circuit is at least capable of
accomplishing the second point. Close the Start switch. You do this by inserting the end of the wire jumper.
The generator howls. Open the switch again, by pulling out the appropriate wire end. The whistle buoy
slowly reduces its frequency. Repeat this play as often as you like.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.105.
130
Components required:
1 x 2N3904 transistor,
1 x 2N3906 transistor,
1 x 10 Ω resistor, 2 x 10 kΩ
resistors, 1 x 47 kΩ resis-
tor, 1 x 100 kΩ resistor,
1 x 10 nF ceramic capaci-
tor, 10 x 1000 μF electro-
lytic capacitor, 10 x Piezo
element, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.105: Whistle buoy