182
2.75 Headphone amplifier
Circuit 157:
Headphone amplifier with Piezo element
Setup information
Install the two transistors, the six resistors and the four electrolytic capacitors as shown in
Fig. 2.157.
The
twelve 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
Components required:
2 x 2N3904 transistors,
1 x 1 k
Ω
resistor,
1 x 2.2 k
Ω
resistor,
1 x 10 k
Ω
resistor,
1 x 22 k
Ω
resistor,
2 x 100 k
Ω
resistors,
1 x 1 μF electrolytic
capacitor, 2 x 10 μF
electrolytic capacitors,
1 x 100 μF electrolytic
capacitor, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.157:
Headphone ampli-
fier with Piezo element
Experiment
Even if everything is wired correctly, nothing will happen at first. If you connect an mp3 player to the input,
you will hear the music blasting from the Piezo element. This little circuit is very useful in various DIY pro-
jects.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.157.
Summary of Contents for ELECTRONICS EXPERIMENTS BOX
Page 4: ......
Page 265: ...267 Fig 3 56 Cir cuit 56 Audio limiter Fig 3 57 Circuit 57 Amplifier for a storm detector...
Page 269: ...271 Fig 3 64 Circuit 64 Stabilizer for 1 9 V Fig 3 65 Circuit 65 Stabilizer for 2 5 V...
Page 275: ...277 Fig 3 80 Circuit 80 Quiztimer 30 seconds Fig 3 81 Circuit 81 Handy diode tester...
Page 315: ...317 Fig 3 179 Circuit 179 HF generator 150 kHz Fig 3 180 Circuit 180 HF generator 420 kHz...
