7400 competition entry: 7400 Logic E-reader

Snorre built a Logic E-reader for the Open 7400 Logic Competition. It is a e-reader build completely from logic chips and 2 eproms. The e-books are displayed on a old analog oscilloscope. The front page says EEPROM instead of EPROM. I don’t have access to a burner right now, so i can’t fix it (ironically, […]

7400 competition entry: Illogical Dickson Doubler

Jonathan entered his illogical Dickson doubler into the Open 7400 Logic Competition. My entry demonstrates how you can use the internal protection diodes and back powering to power a 74HC14 at a voltage “double” (minus diode drops) that of the primary power supply. This method was tested on a 74HC14 and a 74HC595, but it […]

7400 competition entry: The Computer

John’s second entry into the Open 7400 Logic competition is a working computer with serial I/O and a lights ‘n switches front panel. He built a 8bit CPU with a single accumulator, basic arithmetic (+,-,&,~,<<,>>), conditional branching and subroutines, as well as 1KB of RAM. After building and testing that it works, he unfortunately had […]

Frankfurter Buchmesse (book fair) and Thermal Tweeter

irrenhaus gave us a rundown on Frankfurter Buchmesse book fair he visited earlier this year. Here is what attracted his interest and ours: The art installation is the mainly interesting thing:For rows of 34 thermal printers each. All 136 thermal printers were printing – guess what – twitter messages. It was impressive – an impressive […]

PICKit2 clone that works with both 5V and 3.3V devices

Felixls and Suky designed a PICKIT2 clone (machine translation) that works with both 3.3v and 5v devices. Using a 3.3v voltage regulator they have access to both the 5V USB and a 3.3V power supply. Simply by moving a jumper you can chose which supply will power the board and PIC. Via the forum.

7400 competition entry: CMOS digital clock

Giuseppe built his CMOS digital clock two years ago and decided to enter it into the Open 7400 Logic Competition. By using a 2Mhz quartz crystal and a 21bit counter he managed to make a 1Hz clock signal which drives his design. Implementing 2 binary counters programed to count to 60 he managed to get […]

Glass Block LED Matrix, controlled outdoors via tablet

Here is a video from Hive 13 that shows how an Android tablet is used to control a glass block LED matrix via a wireless connection. After installing a LED matrix behind a glass block wall in their bathroom, hackers at Hive 13 are figuring out a way to control them. After some initial struggles […]

7400 competition entry: Four digit RPN calculator

John entered his four digit RPN calculator into the Open 7400 Logic Competition. This is the fist of two entries he made while attending “Digital Hardware Lab” courses at the University of Utah. It is a 4 digit RPN calculator that can add and subtract, designed entirely out of logic ICs. The first few weeks […]

Competition Pro retro joystick USB adapter

Markus decided to reuse an old Commodere 64 Competiton Pro joystick, so he added a USB adapter to it. The retro joystick uses a simple interface over the D-SUB 9 connector, using one connection for each movement direction and one connection per button. He used a PIC24FJ64GB002 microcontroller to translate the native joystick interface to […]

7400 competition entry: TV pattern generator

Ajoy built a TV pattern generator for the Open 7400 Logic competition. Using 74C14 Shmitt inverters to generate various timing signals, he later combines them using a few NAND 74C00 gates to get a B&W TV video signal generator by CCIR-B standards. A full write up explaining the operation of his circuit, along with the […]

7400 competition entry: Lights out game

Bertho entered his Lights out game into the Open 7400 Logic Competition. After working out the math behind lights out, Bertho decided to make his own using only logic chips. The object of the game is to turn the lights off by using a + shaped mask.The board automatically generates random patterns over a 5×5 […]

Fingertip heart rate monitor

R-B built a heart rate measurement from fingertip circuit. He also provided all the design files, and general theory of it’s operation: This project describes a microcontroller based heart rate measuement system that uses optical sensors to measure the alteration in blood volume at fingertip with each heart beat. The sensor unit consists of an […]

Open 7400 Logic Competition: Only two days left to enter!

Reminder to all those interested in entering their projects into our Open 7400 Logic Competition: You only have two days left to send your entry in. Entering Entries can be posted on in our forum, on your personal blog, or even a handy how-to site like Instructables. When you’re ready, please submit a link to […]