171
2.69 Signal tracker
Circuit 145:
Simple signal tracker with Piezo element
Setup information
Install the two transistors, the four resistors and the three electrolytic capacitors as shown in
Fig. 2.145.
Insert the eight jumpers. 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 4.7 k
Ω
resistor,
1 x 10 k
Ω
resistor,
1 x 220 k
Ω
resistor,
1 x 1 M
Ω
resistor,
1 x 1 μF electrolytic capaci-
tor, 2 x 10 μF electrolytic
capacitors, 1 x Piezo ele-
ment, 1 x breadboard,
1 x battery, 9V battery with
clip connector
Fig. 2.145:
Simple signal tracker
with Piezo element
Experiment
Even if everything is wired correctly, nothing will happen at first. If you are familiar with the relevant safety
guidelines as per VDE and know how to observe them when working with devices that are to be connected
to the mains, you can now interconnect the circuit and an external circuit.
When you then touch the individual points at the input that have the audio signals of the circuits to be
tested, you will hear the response coming loud and clear from the Piezo element – no matter if the ampli-
tude is just a few mill volts or several volts. This tool comes handy, if you need to quickly locate a broken
level in an audio circuit.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.145.
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...
