7400 competition entry: 7400 Dimmer

Control your lights via a 7400 based dimmer. This is RodLophus’ entry for the open 7400 Logic Competition: The idea is: For a typical dimmer, when you apply a pulse on the gate terminal of the TRIAC, it turns on – and stays on until the mains voltage crosses the 0V. So, varying the “firing angle” […]

7400 competition entry: Mr. @#?%!…A 74xx based Q*Bert-ese obscenity generator

Here’s David’s 7400 entry, the Mr. @#?%!…A 74xx based Q*Bert-ese obscenity generator: In honor of the 30th anniversary of Q*Bert’s release in arcades, I present “Mr. @#?%!”… A 74xx-based Q*Bert-ese Obscenity Generator, built exclusively using parts available in 1982. Build something that uses or abuses a logic chip and get amazing boards, tools, and other […]

7400 competition entry: CMOS frequency counter

Miguel sent in his entry to the open 7400 competition. It’s a CMOS frequency counter based around the CMOS 4000 series logic chips. It’s capable of counting for 1 Hz up to 1 MHz. The project consists of a frequency counter that uses only old-school CMOS chips: 4511 display drivers, 4029 decade counters a 4521 […]

7400 competition entry: World’s most useless machine

Check out Alex’s useless machine with a chain switch. It’s operated with 4 servos and uses 11 7400 logic chops. It’s his entry to the Open 7400 Logic Competition: This is a last minute (and very useless) entry. I wanted to make something that shut itself off, but I wanted it to be different than […]

7400 competition entry: DIY musical keyboard

Oakkar7 shows you how to make an awesome DIY musical keyboard using only 7400 logic. The idea is to design and construct an electronic musical keyboard with some functions, effects etc,. This is my old school project and I remake and modified it. It is fun. Build something that uses or abuses a logic chip and get amazing boards, tools, […]

7400 competition entry: Lineclock

This open 7400 competition entry is a clock which displays it’s time as text on 32 5×7 dot matrix displays. The display itself is driven via a board that was scavenged from an East-German numerical control unit. I build this clock with an old display-board from an east-german numeric control. It has a one-line display […]

7400 competition entry: Bug shaped robot

Here’s a bug shaped robot entered into the open 7400 competition. Power by a solar panel, this 7400 logic based robot moves toward the life giving light source. Powered by a solar panel, this miniature robot shuffles towards the light.  This project was a venture into BEAM robotics, a now seemingly defunct genre characterized by […]

7400 competition entry: Quiz Show Buzzer

Need a quiz show buzzer system? Check this out! A Quiz Show Buzzer was just built only with 74XX series device. A single 74LS373 Octal D-Type Flip Flop was used instead of several AND gates. Eight DATA INPUTs serve as quizzer’s user interface and the eight DATA OUTPUTs were connected to 8-input AND gate which […]

7400 competition entry: A game of Tic Tac Toe with logic IC’s

Do you like to play games? Try this Jayahari’s fun Tic Tac Toe game: First of all thanks to DangerousPrototypes! its because of you guys I worked on logic gates after college – else its usually the usual microelectronic stuff! :) This build is a simple ‘Tic Tac Toe’ game. I ended up using 30 Logic […]

7400 competition entry: Fourbit, 4-bit homebrew CPU

Here’s another Open 7400 competition entry a 4-bit homebrew CPU designed by Jaromir: Since I was born in mid eighties, I’ve never experienced real 74xx build. Few gates here and there was common, but lager designs were practicaly uneeded – as microcontrollers, CPLDs or FPGAs replaced need for such as work. But my posession in […]

7400 competition entry: 7400 Logic Based Calculator

7400 Logic Based Calculator is the open 7400 competition entry by students of the Pakistani Institute of Industrial Electronics Engineering. This was an assignment during their 6th semester course Digital Electronics II. Digital logic based calculator built on 7400 series ICs which can add and subtract two digits with clear, and backspace as well This project […]

7400 competition entry: 7400 ping))) pong

Alex entered his 7400 ping))) pong video game into the 7400 Logic Competition. It’s a clone of the old TV console classic, but implemented with 7400 logic and 556 timers (twin 555s). The project took a total of thirty 7400 chips and 556 timers. There is no microcontroller, just discrete logic. It keeps score by the […]

7400 competition entry: Mathemagic – Mind Reader

Mathemagic, mind reader or a decoder, you decide. This open 7400 competition entry bases it’s magical properties in a mathematical game of coding and decoding numbers in binary sequences. The concept behind this is a BCD to 7-Segment decoder(IC7447). The unit and tens place of the number are in BCD. For example let’s consider the […]

7400 competition entry: Direct digital synthesis arbitrary waveform generator

Arbitrary waveform generator  designed by NiHaoMike is a Open 7400 competition entry. It uses a serial link with a computer to load up a W24512A SRAM IC which is then clocked out into a TLC7524 digital to analog converter. This is really just for fun – it doesn’t make a very good function generator by […]

7400 competition entry: Relative clock/timer/alarm

  Relative clock/timer/alarm designed by Victor, and entered in the open 7400 Logic Competition. Towards the end of the ’80s, when I started out in electronics, one day I decided to make a special alarm clock: one, that, when the time comes, switches on some device in my room – be it a radio, TV […]

7400 competition entry: Flickery LED bar candle

Looking for Halloween do-it-yourself project that will make your friends have a frightfully fun time? Check out T0m’s flickery LED candle: Here’s a 1 chip wonder. i wouldn’t call it the height of originality — just a bit of fun for Halloween! :) Build something that uses or abuses a logic chip and get amazing […]

7400 competition entry: Random number generator

Mike posted his hardware RNG based on discrete logic chips for the Open 7400 Logic Competition. Generating truly random numbers using a purely digital circuit is not possible – after all, digital logic is supposed to give the same results given the same input! This circuit cheats a little – a 4049 is used in […]

7400 competition entry: Passive RFID Tag from 7400 discrete logic

Check out Bertho’s RF74xxID, a multifunction passive 7400 RFID tag for the Open 7400 Logic Competition. RF74xxID: A passive RFID tag built entirely with 74xx logic chips. The tag supports the setting of any ID by means of DIP switches, can send data using two encoding schemes and has configurable baud rate. The tag is […]

Open 7400 prize: $25 gift cirtificate with free world wide shipping from Numato

Numato Lab donated a $25 gift certificate with free world wide shipping to the Open 7400 Competition. Numato is an online hobbyist electronics shop based out of Banglore, India. Get your entry in and this and other cool prizes can be yours. Thank you to Numato for sponsoring the 2012 Open 7400 Logic Competition!

7400 competition entry: Hacky random number generator / cat toy

Want to make your own toy for your cat? Tom’s random number generator shows you how: I decided to make a true random number generator. In particular, I wanted a latching RNG — not merely a continuous stream of numbers, but a continuous stream which I could sample at intervals. The circuit would be made up […]