Table of Contents
Advertisement
Circuit 69: LED blinker 3 Hz
Setup information
Install the two transistors, the diode and the five resistors as shown in Fig. 2.69. Then install the three
electrolytic capacitors. The 13 jumper wires are next. Check the placement on the board again and only then
connect the battery.
Experiment
Even though, everything is wired correctly and the battery is installed, it may take some time until some-
thing happens. The circuit produces sine waves at a frequency of about 3 Hz. It will take a while to come to
life. But then it works reliably and tirelessly. The red LED flashes at regular intervals, gentle on the eyes. The
LED is not turned on or off abruptly, but increases and decreases its brightness steadily towards the respec-
tive turning point.
The circuit diagram for this experiment is shown in Chap. 3, Fig. 3.69.
94
Components required:
2 x 2N3904 transistors,
1 x red LED, 1 x 220 Ω
resistor, 1 x 2.2 kΩ resistor,
1 x 10 kΩ resistor,
2 x 22 kΩ resistors,
1 x 10 μF electrolytic capac-
itor, 2 x 100 μF electrolytic
capacitors, 1 x breadboard,
1 x 9V battery with clip
connector
Fig. 2.69: LED blinker 3 Hz
Advertisement
Table of Contents
