7400 competition entry: Animated LED Christmas sign

Raj entered his Animated LED Christmas sign into the Open 7400 Logic Competition. Having already build a PIC controlled version, he wanted to try and control the sign using discrete logic only. The individual letters are build from red LEDs and run of a 32V power supply. Check out the video of this project below. Via […]

7400 competition entry: Masochist’s video card

Chris entered his Masochist’s video card into the Open 7400 Logic Competition. Using only discrete logic his circuit cycles through 8 presettable colors at a variable frequency. Using a simple resistor network he outputs it over the VGA output. It is well documented and all the design files are available. Check out the video below. Via […]

7400 competition entry: Discrete logic POV clock

Matt’s entry in the Open 7400 Logic competition: Discrete logic POV clock. This persistence-of-vision clock was built entirely out of discrete logic chips. The design consists of three boards, a LED array and a drive motor. The digit board keeps the time while the display board controls the LEDs. The digit board Every second, a pulse increments the […]

7400 competition entry: Discrete servo driver

Here’s an entry in the Open 7400 Logic competition: Discrete servo driver. This entry is designed to control RC hobby servos. 8bit parallel BCD code input from a dip switch sets a pulse width between 0-25.6ms (180 degrees of motion). However on most servos the first 50 and the last 10 positions are unavailable so you have […]

7400 competition entry: 74LS00 based full wave rectifier

Noels entry for the Open 7400 Logic competition is a 74LS00 based full wave rectifier. I want to have an entry that it simple enough that other people can try out with their breadboards.  Something that is easy to do, and yet feature a mis(use) of a typical 74LS00 IC.