Murphy’s law is a undisputed fact of life, and this app note by Maxim explains how it impacts electronics design. This application note considers off-data-sheet operation of integrated circuits (ICs). It discusses the pitfalls awaiting engineers who have not experienced Murphy’s Law, which is anything that can go wrong, will go wrong at the worst […]
Author Archives: DP
Free PCB Sunday: Pick your PCB
We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will […]
App note: Implementing PID on PIC18 microcontrollers
PID is implemented when a precise way is needed to drive an external device that provides feedback. Heaters with temperature sensors, and servo motors are examples where PID is used. This app note by Microchip gives instructions how to implement PID control in PIC18 projects. Basic terms are explained inside the document as well as […]
App note: Understanding Schmitt triggers
Most logic ICs require fast transitions between levels to function properly, while the switch is being made the IC draws additional current, and if it is kept in this intermediate state failure of the chip is possible. This app note explains how Shmitt triggers are used in circuits that require slow changing signals to drive […]
Reading I2C temp sensor without uC
Schazamp tried to read an I2C temperature sensor using only logic chips. It isn’t working yet, but the writeup is impressively detailed: My project is to use logic devices to read a TC74 temperature sensor. The general idea is to have some kind of master clock (from 3 of the 74HC04’s 6 inverters), manipulate the […]
App note: Performance enhancement of three terminal voltage regulators
Three terminal voltage regulators like the lm317 are common and easy to use, for most applications only two additional resistors are needed to get a stable power supply. This app note by Linear Technology provides guidelines how to increase the performance of these devices. Current output could be increased from a few amps to tens […]
7400 competition entry: Flickering Jack-o’-lantern
Jonathan entered a Flickering Jack-o’-lantern for the Open 7400 Logic Competition. He recorded a video of his project, which is available below. I used a 74HC14 to create four different square waves of different non-harmonic frequencies that were mixed together to flicker a red and blue LED. Via the contact form.
7400 competition entry: Logic PLL based switch-mode power supply
Embeddederic entered a 7400 series logic PLL-based switch-mode power supply into the Open 7400 Logic Competition. Via the forum.
Week in (p)review: October 21, 2011
Facebook free PCB Friday is on the way. Don’t forget to share your current project in the comments or the forum. Here’s a summary of major developments over the last week: The Open 7400 Competition deadline (October 21, 6am GMT) has passed HamRadio2008 made a demonstration video of the Bus Pirate in I2C mode DIY […]
7400 competition entry: 80M direct conversion receiver
Jason added another entry to the Open 7400 Logic Competition: 80M direct conversion receiver I had fun using the 74HCU04 to make a little TRF AM radio, but my original goal was to build a direct conversion receiver. I didn’t think I would have time before the deadline, but I managed to squeeze it in with […]
7400 competition entry: Game of Life with CMOS logic
Andrey entered a Game of Life build from CMOS logic into the Open 7400 Logic Competition: This was supposed to be my entry for Open 7400 logic competition. It’s Conway Game of Life on 8×8 LED dot matrix, made with almost only 74HC and 4000/4500 series of CMOS logic chips. Via the contact form.
7400 competition entry: Homemade 7400
Arup entered his Homemade 7400 into the Open 7400 Logic Competition. A video of it proving his concept is available below. At an earlier post I’ve said that I didn’t have 7400ICs in my drawer. Surprisingly, the local store was saying 74HC00 out of stock. Hence I decided to make my own 7400 IC. 7400 […]
7400 competition entry: Ternary base-3 electronics using 74HC4052
Shaos entered a (balanced) ternary electronic device based on the 74HC4052 into the Open 7400 Logic Competition. Ternary Balanced ternary is a base-3 number system, instead of bits (0, 1, 10, 11, etc), this counts in trits (-1, 0, 1): The “Test bed” consists of 20 sockets for testing “our standard ternary components“. For ternary […]
7400 competition entry: C-IR capture device
Kevin entered a Detailed consumer IR capture with 74HCxx series chips for the Open 7400 Logic Competition: This is a CIR (Consumer IR / Remote Control) capture device built with 74HCxx series logic chips. It allows a computer to do a detailed capture with carrier frequency, on/off durations, and on duration pulse counts. Via the […]
7400 competition entry: 8-Channel, 6 -MSPS USB logic analyzer
Helmy entered an 8-Channel 6MS/s USB logic analyzer into the Open 7400 Logic Competition. His device converts the 8 channel parallel inputs into a UART based serial signal. It outputs this serial signal to the input pin of a PL2303 USB-to-Serial chip which sends the data to the computer. Via the forum.
7400 competition entry: Discrete Logic Drum machine
Matt built a fully featured Drum machine for the Open 7400 Logic Competition. Check out the video of its operation and his sound generating skills below. This is a four-channel, sixteen-step percussion synthesizer/sequencer created entirely from discrete logic chips (mostly 74HC-series parts). That’s right, no microcontroller or software of any sort. It was created for […]
7400 competition entry: Horologium Romanum
Joe entered his Horologium Romanum into the Open 7400 Logic Competition. It is a clock that displays it’s time in Roman numerals built from logic ICs. There is a video of it below. Despite the Roman Empire’s sanitation, medicine, education, wine, public order, irrigation, roads, fresh-water system, and public health: they never had a decent […]
7400 competition entry: Wheely bin night reminder
Luc entered his Wheely bin night reminder into the Open 7400 Logic Competition: Because the competition was so open ended in its brief, I placed two constraints on myself: First, I had to make do with the logic chips (and other components) I had on hand. No going to Jaycar or placing an order through […]
7400 competition entry: Heat generator
After being discouraged by a failed order for their initial entry, Ben and his girlfriend decided to enter a somewhat different design into the Open 7400 Logic Competition. It consists of taking their anger out on 7400 chip. By pumping 1 Amp of current at 12V into the IC, they turned it into a heater, […]
7400 competition entry: Etch-a-Sketch toy
Daniel entered an Electronic realization of Etch-A-Sketch toy into the Open 7400 Logic Competition: This project is an electronic realization of the famous Ohio Arts “Etch-A-Sketch” toy, with a twist. Like the original, two rotary knobs are used to move a cursor horizontally and vertically, respectively, but unlike the original, a third knob selects one […]