Giant LED bar graph

 by chunkyhampton
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For a recent project I needed to build a large and obvious bar graph display. This was to show the power generated from a bicycle generator. I came up with this design and was pretty pleased with the final results as it is relatively low cost but still pretty visual. It stands 1.5m high and 10cm wide. It needed to be low power but bright so I used LED arrays.
Here I show the process of building one. This one has 10 light elements, but can easily be extended to suit your idea.
It is designed to be controlled using an Arduino devleopment board, but uses logic shift registers, so can be easily controlled by any microcontroller.

The video here shows the unit in action.

 
The main body is built from electrical trunking, which is available in 2 and 3m sections. This forms a relatively cheap, robust and long enclosure.
The LED light units are 12V DC units from Phenoptix. The PCB was designed by Big Clive and is designed to fit into a standard MR16-type 12V halogen light fitting. They are available in all different colours, including as an RGB array.
 
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Step 1: Parts and tools required

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Parts required:

Electrical trunking 100mm x 50mm in 2m lengths.
I got mine from Screwfix (http://www.screwfix.com/p/maxi-trunking-100mm-x-50mm-x-2m-pack-of-6/99297) but its available in all electrical supply places
2 x End caps for the trunking
Again from Screwfix (http://www.screwfix.com/p/tower-end-cap-100-x-50mm-pack-of-2/46339)

Sheet of 'frosted' polypropolyene
I got mine from Paperchase, but you can use thin card or plastic from milk bottles or other stuff here.

10 x 12V LED units.
These were designed by Big Clive (http://www.bigclive.com/) and obtained from Phenoptix (http://www.phenoptix.com/) and have 9 x 'super flux' LEDs on them.
I used 5 green, 3 yellow, 2 red to give an indication of power level.

3mm Machine screws 20mm long
3mm locknuts

Wire
Glue - hot melt glue gun would work, or any general purpose glue.

Control circuit:

74HC595 Shift register (http://www.nxp.com/documents/data_sheet/74HC_HCT595.pdf)
 ULN2003 NPN Darligton transistor array (http://www.datasheetcatalog.org/datasheets/120/489337_DS.pdf)
0.1uF capacitor
100uF capacitor
Piece of strip board (also called veroboard)

When I built mine the total cost of parts was around £100 (including £60 for the LEDs, £20 for the trunking, £5 for the end caps).

Tools:

58mm hole saw
Hacksaw for plastic
3mm drill bit
Drill
Soldering iron and solder
Screwdriver
Pliers
Strip-board cutter (to cut the tracks in the stripboard - you can also use a drill bit to do this)
shivatek says: Jul 6, 2012. 9:13 AM
Can you post the kiCAD Files? Thanks :)
frandevedia says: Jun 27, 2012. 3:58 PM
Hi! great work. Could you share the circuit schematic in a better quality? thanks
chunkyhampton (author) in reply to frandevediaJun 28, 2012. 12:57 PM
Of course. I'll sort it out now.
The files were done using KiCAD, so if anyone would liek the KiCAD files then just ad a comment and I'll post them up.
Matt
frandevedia in reply to chunkyhamptonJul 4, 2012. 8:55 PM
great!
thanks!!
phenoptix says: May 9, 2012. 2:51 AM
Great work Matt! Also well done Adam on the pedalling.
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