SSL/TLS library side by side comparison

Brian stumbled on this side by side comparison of SSL/TLS libraries and gave his review of it: So in summary of what code bases I find usable from a licensing prospective: TropicSSL and axTLS are clear winners in terms of the license CyaSSL and PolarSSL are GPL V2 + FLOSS which is less desirable Next I looked […]

7400 competition entry: Analog comparator

Joseph built an analog comparator for the Open 7400 Logic competition. Using two NAND 3-input gates and a D-type flip-flop, he build a clocked analog comparator. After reviewing the internal composition of a CMOS NAND 3 gate he noticed that two of them connected in the right way make up a comparator. To make his own version he used a D-type flip-flop to […]

How-to use surface mount parts with a breadboard

Pppd shared a tip for using surface mount parts with a breadboard, mount them on 0.1″ pin header: Also, I’m probably not the first one to do it this way… but if you don’t like through-hole parts just as much as I hate them you may want to use surface mount resistors, capacitors or even […]

Voltage monitor for car’s battery and its charging system

Raj designed a car battery volt-meter. The core of the project is a PIC16F1827 which uses its internal fixed voltage reference FVR and ADC to precisely measure the battery voltage. Measured voltage is displayed on a 4 digit 7 segment display. His circuit is connected to the car’s battery through a standard car lighter jack. Via the […]

I2C controled 8 relay driver switches plug-in devices

Megabug posted his I2C relay driver board for controlling 8 outputs. It controls 8 relay switches in which one pin of each switch is common, while the other pins are available through 8 screw type headers. It uses the PCA9554 8bit I2C port expander to drive a ULN2803A buffer which in return drives the relay coils. All buffer input […]

#FreePCB via Twitter to 2 random RTs

Every Tuesday we give away two coupons for the free PCB drawer via Twitter. This post was announced on Twitter, and in 24 hours we’ll send coupon codes to two random retweeters. Don’t forget there’s free PCBs three times a every week: Hate Twitter and Facebook? Free PCB Sunday is the classic PCB giveaway. Catch […]

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 […]

HAKKO soldering pencil driver update

Arhi compares his soldering iron driver with commercially available products. After designing and building a open source soldering station for Solomon or Hakko soldering pencils, he posted a full analysis of his project. While his driver has some overshoot, once it stabilises the temperature has less swing then the original drivers. With some PID tuning even better […]

Controllable aquarium moonlight strip

Theatrus build a controllable aquarium moonlight strip. Royal-blue Osram high power surface mount LEDs provide the lighting, and an ATmega88 the control. RS485 port is used for control. All of the design files should be available shortly. Its quite potent (visible with the main 6x80W T5s running). Its easy to mount (a handful of command strips […]

IR helicopter automatic altitude control

Amieres built a IR controlled Helicopter with Wiimote using USB IR Toy V1. A camera connected to the laptop tracks the helicopter. Using the USB IR Toy the laptop sends automatic altitude control signals. Setting attitude points is done with Wiimote’s up/down buttons, while nunchuk joystick is used for motion control. Via the comments. You can get […]

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 […]

Sparkfun has new oscilloscope

Sqkybeaver let us know Sparkfun now carries a scope similar to the one he reviewed. It is a two channel 100MHz digital scope with 500MSa/s real-time sampling rate. Saving waveforms to a USB flash drive is available, as well as interfacing with the computer over the USB port. The waveforms and menu are displayed over a 5.7″ LCD Screen. Via the forum.

App note: High speed USB design guidelines

This app note by Intel covers how to design for high speed USB. It’s full of great tips for your next project. While mainly written for multi-layer motherboard design, we picked up tips on proper termination and routing techniques. We picked up tips on routing and placement guidelines, trace length and spacing, proper termination, plane splits, […]

App note: Building a stable DAC external reference circuit

Having a stable external reference is important in digital-to-analog converter design and this app note helps. For a DAC to function properly it must have a stable reference to create a precise output signal. Unfortunately because it is a simple concept, proper reference design is usually overlooked. In this app note from TI a simple force and […]

App note: Driving LEDs in battery-operated applications

Driving many LEDs from a battery can be a pain to do, especially if you need many of them to have the same brightness. One way to do this is to use current mirrors for each individual LED, and drive them from the battery voltage only. Another is to drive them with a dc-dc boost converter in […]

STM32L-Discovery board and ChibiOS/RT

Getting started with the STM32L-Discovery board and ChibiOS/RT: This article will explain how to get started with the recently released STM32L-Discovery board using ChibiOS/RT. This board is really cheap (around 12$) and is an excellent evaluation platform for the STMicroelectronics STM32L family. Thanks Giovanni! Via the contact form.

App note: Using Microchip’s capacitive sensing module

Capacitive sensing is used in tons of stuff like buttons, sliders, touch panels and proximity sensors. We like it because you only need to design the various buttons/sliders directly on the PCB and it works even under a face plate. It works by measuring the changing capacitance between a pad and a users finger as […]