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Lab 2 designs - Riddhi Mittal

Page history last edited by Riddhi 10 years, 5 months ago

20 LED Light Application Designs -


The checked ones are the ones I made paper prototypes for.



Paper prototypes for my 10 favorite designs


Head band with light. 


Bike light / Flash light


Toy Traffic light.


Making Tracing Paper Easier->

An LED light has been put inside a transparent glass surface. An opaque paper with writing on it is placed on top of the glass. Another opaque paper on which we need the writing from the previous paper traced is placed on top of the previous paper. As you can see, everything from underneath the opaque paper is clearly visible and tracing is possible.


Flash light for camera


LED lights as status indicators - when the phone has started charging - an LED light connected to the charger should light up as a visual signal.


LED light inside wallet to help see its contents in the dark.


Awesome superhero sweatband ->


RGB Color Mixer ->

Let's user turn three knobs and see resulting RGB color on LED light and read off the corresponding R, G and B values from the displays.


Digital Clock - shows hours and minutes - uses four 7-segment displays


The LED Light Design I finally built ->


I really liked the digital clock and wanted to build it. So, I bought four 7-segment displays from RadioShack and proceeded to build it on the breadboard.


I did not know of a way to actually poll the computer or the chip itself for the current time. So I decided I will use a hard-coded start time, and the clock will start ticking from that hard-coded time when it is turned on using the switch. As it was designed, my clock would start over again every time it was turned off and then turned on. Not the most intuitive clock in that sense - but when on it showed you time correctly. I guess it was more like a StopWatch then.


The 7-segment displays had 7 anodes each, each anode controlling one segment on one display, and one common-cathode for the 7 segments each. The 7 anodes from all four displays were connected to the same 7 pins on the arduino. The 4 common-cathodes of the four displays were connected to 4 different pins on the arduino. Every loop() would cycle through the four displays with a short delay of 5 ms in between and set the value for the 7 segments for that display to show the correct number. Because of persistence of vision, it would seem like all 4 displays are lit up and show 4 digits at one time.


When it worked on the breadboard i.e. showed time correctly, I proceeded to move it to the perfboard.

My circuit had atleast 40 wires. The 4 displays required apprx 50 pins to be sottered on the perfboard. The arduino required another 20 pins to be sottered onto another perfboard. To cut a perfboard into two, I used both the nibbler and the dremel. Then I had to sotter 4 wires to a single arduino pin and I decided to sotter blob them in horizontal lines protruding out from the sottered arduino pin on the perfboard.


After 5 and a half hours in the lab spent sottering all the 40 wires onto the arduino perfboard and sottering about 5 more on the other one, I realized it was impossible to be able to connect all the wires already sottered to the arduino perfboard onto the display perfboard. Below are pictures showing why -


NOTE - So I am considering this one to be my final LED Light design. I really like the tracing concept.





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