3X7
3X7
Seven segments from individual LEDs
Seven segment displays are and have been very common in electronics. Usually, the 'seven segments' are encapsulated into a single component, with a common anode or cathode and seven (sometimes eight for a dot) control lines.
With our 3X7 project you'll construct a three-digit seven-segment display from discrete components. There are three control lines, one for each digit, and the seven segments are multiplexed.
The LEDs themselves shine though a thin 1mm PCB.
3X7 was project #28 of the Boldport Club.
What’s included
14x 2x5mm lens red LEDs, Valcon VRLED-52-R
7x 2x5mm lens yellow LEDs, Valcon VRLED-52-Y
1x 1x12 right angle header, Multicomp MC34757
4x N-channel MOSFET transistor , 2N7000_D26Z
18x 1KΩ resistors, MF25 1K
7x 470Ω resistors, MF25 470R
1x Lovely PCB panel
Thanks to Toby Electronics for providing us with a great price for the rectangular LEDs.
Assembly
This project is a challenge to construct. Take your time. Assembly instructions are provided in the infographic. Make sure to be grounded to avoid static damage with the FETs, and to test them before and after soldering them.
Software
We're fortunate that LuckyResistor has written a driver for 3X7, which can be used with an Arduino Uno or ported to other devices. The code can also be extended to control more digits.
Additional information
Community contributions for this project
Open source circuit board design files