69
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
Components required:
2 x 2N3904 transistors,
1 x 100
Ω
resistor,
2 x 1 k
Ω
resistors,
1 x 2.2 k
Ω
resistor,
1 x 10 k
Ω
resistor,
1 x 22 k
Ω
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
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.
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...
