Home > Circuit Bricks > 7-Segment Display
UPDATED:.17:16 28 August 2011
FUNCTION BLOCK
DESCRIPTION

LED Arrays such as Bargraph types are usually formed from a row of LEDs next to each other.

These are useful for showing quantities or levels - such as an audio VU meter.

7-Segment Display
CIRCUIT DIAGRAMS

7-segment displays are 7+1 LEDs in the same package shaped to form the number 8. From these 7 segments, any other number can be formed, some letters also.

Each segment is allocated a letter to identify it, a to g.

Displays come in 2 variations, Common Anode or Common Cathode - these are shown right.

In most circumstances (unless specifically stated by an IC, an LED must have a resistor in series with it to prevent damaging it.

For voltages between 6 to 12v, a 470 ohm resistor will be fine but to get maximum brightness, without damaging it, you should work out the correct value.

The LED page has more information on how to do this.

You can make larger displays by combining them - to find out more go to
Building Giant 7-Segment Displays.
Circuit Symbol -
Common Anode

All anodes connected
together to form a common
anode connection. Cathodes
connect to current sinking
outputs.

(Internal Connections)

Circuit Symbol -
Common Cathode

All cathodes connected
together to form a common
cathode connection. Anodes
connect to current sourcing
outputs.

(Internal Connections)
DISPLAY TYPES AND CONNECTIONS
There are many types of
7-segment displays.

Some common types around 0.5" high have connections as shown right.
Raising the Height.

Usually the displays are mounted on the PCB. You can raise the height of the display by soldering SIL turned pin sockets and plugging the displays in to these.

There are also StarBurst displays which have 16 segments. These can display numbers and letters - they are alpha-numeric.
Written by Phil Townshend - 2008
www.edutek.ltd.uk - Working Electronics For Students & Teachers