Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 214

Circuit 191: Simple active probe with Piezo element
Setup information
Install the two transistors, the two diodes, the four resistors, the ceramic capacitor and the electrolytic
capacitor as shown in Fig. 2.191. The thirteen jumper wires come next. Finally 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
The active probe operates in a frequency ranging from 100 Hz to approximately 1 MHz. If our circuit is used
within the NF range, you will hear the signal coming from the Piezo element.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.191.
216
Components required:
1 x 2N3904 transistor,
1 x J111 FET transistor,
2 x 1N4148 silicon diodes,
1 x 1 kΩ resistor,
2 x 10 kΩ resistors,
1 x 1 MΩ resistor,
1 x 100 nF ceramic capac-
itor, 1 x 10 μF electrolytic
capacitor, 1 x Piezo ele-
ment, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.191: Simple active probe
with Piezo element