Physically Huge 7-Segment LED Display

The project is a 12” digit height 7-segment display which was made from 15×4 LEDs wherein 4 LEDs are connected in series and fifteen times in parallel arrangement.

An independent piece of molded plastic located on a huge but inexpensive circuit board pertains to each segment of the display. The segments are held in the right places by the circuit board that functions as a mechanical fixture. The whole circuit can run well at 100mA current where across the LED part consumes around 21V. this would require taking a 24V power supply instead of 12V/9V which could not support higher voltages.

In the microcontroller part of the design, one of the target boards was used in order for the seven transistors to be driven as GPIO outputs. The board includes the ATmega168 along with the wires to the transistor drivers and the programming header. Using USBtinyISP, the power can be obtained from a USB port. The big 7-segment display would turn so bright that the wall near it would be lit up by the pure red glare while also in pure red are the segments themselves giving washed-out colors on digital camera shot.

Rest of the project