Maker Factory ELECTRONICS EXPERIMENTS BOX Manual page 203

Circuit 180: HF generator 420 kHz
Setup information
Install the transistor, the four resistors, the four ceramic capacitors and the fixed value inductor as shown
in Fig. 2.180 followed by the eight jumpers. Check the placement on the board again and only then connect
the battery.
Experiment
This circuit generates HF radio waves at a frequency of about 420 kHz. A portable MW radio makes the first
harmonic of this radiation audible at 840 kHz. This is a standard circuit in analogue receiver technology and
known as Colpitts oscillator.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.180.
Components required:
1 x 2N3904 transistor,
2 x 10 kΩ resistors,
2 x 22 kΩ resistors,
3 x 1 nF ceramic capaci-
tors, 1 x 100 nF ceramic
capacitor, 1 x 220
μH fixed inductance,
1 x breadboard, 1 x 9V
battery with clip con-
nector
Fig. 2.180: HF generator
420 kHz
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