PAGE 057 OF 150 · WIRING LEDS
Wiring a Seven-Segment Display
Each segment is one LED with its own resistor.
LED SYMBOLTriangle points from anode to cathode; the arrows show light leaving the part.
The display
A seven-segment display holds eight LEDs, seven segments labelled a to g and a decimal point, in a 10-pin package. Pins are either common cathode or common anode.
Wiring
- Connect the common pin to ground for common cathode, or to supply for common anode.
- Put a 220 to 330 ohm resistor in series with every segment, not on the common pin.
- Light segments a, b, c, d, e and f for a zero.
Pin layouts differ, so find the segments with a coin cell and resistor or the meter diode test before building.
REMEMBER
In series the same current flows through every LED.Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.
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