Table of Contents
Advertisement
2.18 Two-stage AF amplifier
Circuit 44: Two-stage AF preamplifier
Setup information
Install the two transistors and the six resistors as shown in Fig. 2.44. Then install the three electrolytic
capacitors. The seven 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
An AF preamp amplifies low-power audio signals like those coming from microphones and pickup heads to
the extent that they could be used to drive an audio power amp.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.44.
Components required:
2 x 2N3904 transistors,
1 x 100 Ω resistor,
2 x 1 kΩ resistors,
1 x 2.2 kΩ resistor,
1 x 10 kΩ resistor,
1 x 22 kΩ resistor,
2 x 10 μF electrolytic
capacitors, 1 x 100 μF
electrolytic capacitor,
1 x Piezo element,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.44: Two-stage AF
preamplifier
69
Advertisement
Table of Contents
