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Open Circuits

These should be projects or links to projects that are open, at a minimum in the sense that there is enough information so that others can reproduce the project. Lets stay away from sites that are just show cases without the details.

SD Card Bathroom Scale

On SD Card Bathroom Scale project I hacked a cheap commercial digital bathroom scale, for write (log) my weight variations over time, on a memory SD Card. I write the information (time + weight) on a comma separated values (CSV) file (weight.csv) so I can quickly build a graph using OpenOffice.

Programmable Chip EEG

The Programmable Chip EEG is a Multi-channel electroencephalograph that could be a brain-computer interface. See the OpenEEG Project

N8VEM Home Brew Computing Project

The N8VEM Single Board Computer (SBC) is a home brew Z80 small computer project. It is made in the style of vintage computers of the mid to late 1970's and early 1980's using a mix of classic and modern technologies. Its purpose is to entertain through education. It is intended to be used to teach and promote principles of electronic computer design. It is a solely non-profit educational project and is not intended for any commercial application. Please see the wiki for detailed information on the N8VEM project. N8VEM Mailing List N8VEM wiki

Open Source Disability Gadgets

  • "Gear and software for people with disabilities is usually ... hard or impossible to repair it, or get anyone to repair it. We need to hack the model for accessibility tools! With a culture of open source designs, Instructables, wikis, and blogs" -- Open Source Disability Gadgets: DIY for PWD


  • uWatch aka µWatch: World's First D-I-Y Scientific Calculator Watch

Open Source Circuits Magazine

Anykits magazine - Anykits publishes an open source magazine with quite a few, application oriented circuits. It contains schematics, parts list and PCB illustrations. The best part is that its formated for print and available as regular PDF.


Link to source and schematics Open source hardware and software implementing OBDII tester for cars. Two versions one using a PIC microcontroller and one using an AVR microcontroller.

vehicles: manned and unmanned

Lots of vehicle-related projects -- for motorcycles, automobiles, and unmanned aerial vehicles (UAVs).

Phone line relay controller with PIC16F84A - single relay

  • [1] controll one relay over phone-line. Uses PIC16F84A and MT8870.

Phone line relay controller with PIC16F876A - 6 relays!

  • [2] controll up to 6 relays over phone-line. Uses PIC16F876A and MT8870.

Homemade MIDI turntable

Cheap and simple homemade MIDI turntable with GPL2 license. Using a ATmega, a HDNS-2000 optical mouse encoder, GCC-AVR, AVR-Libc and FreeRTOS. Homepage of Homemade MIDI turntable.

Motherboards that Run Linux

Elphel camera

Elphel cameras are free software and open hardware cameras. The cameras run Linux. The cameras have several interfaces -- 10/100 Ethernet, USB, IDE, RS-232, etc. It uses a FPGA for video processing and video compression. More information here at Open Circuits: Elphel camera; and at the Elphel wiki.

ARMUS Embedded Linux Board

An ARM920T board running Linux at 200 Mips with sound, Ethernet, CAN, 48+ bidirectionnal IOs and 4 DSPs for motor control (DC, Servos, etc...). Built as a student proof robotics design platform.

Balloon Xscale ARM+FPGA dev board

The Balloon project has produced Balloon3, a high-performance ARM board designed for use by OEMs and Higher education. Spec is PXA270 (583Mhz), FPGA or CPLD, 1GB flash, 784MB RAM, USB (master, slave, OTG), CF slot, expansion bus, 16-bit bus, I2C, LCD, serial, audio. Very low power in CPLD confiuguration. Small, light. Various add-on boards: VGA LCD driver, robot motor driver+A/D, digital IO. Released under the Balloon Open Hardware license, which allows anyone to manufacture and for people to make derivatives. The expansion bus allows balloon to be used as the computing component for various special-purpose devices.


The linuxstamp is an open source processor module. It is designed to be a very simple board capable of running linux. It is based on the Atmel AT91RM9200 processor (An ARM9 processor with a MMU).

Linuxstamp Mboard 1

This is the first mother board for the linuxstamp. It is still in the planning stages (no pcbs).

Linuxstamp II 9260

The Linuxstamp II is an open source processor module. It is designed to be a very simple board capable of running linux. It is based on the Atmel AT91SAM9260 processor (An ARM9 processor with a MMU).

LART -- an open license StrongARM based tiny SBC

"All CAD files required for building LART are available under the closest we could get to an Open/Free Hardware License." The link in the Linux Devices article no longer works; the most recent link is .

Gumstix - Motherboards the size of a stick of gum ---

These motherboards are based on a SBC, are inexpensive, and have RAM/Flash on board. The Modules include USB interface (gadget mode and host mode) and have things like GPIO and LCD module interface. They have Marvel PXA270, TI's OMAP3503, etc. Very cool site.

Other Boards that Run Linux

Open Mobile Gadgets -- open source, open hardware, mobile phone

An open source, open hardware mobile phone in its preliminary development.

  • Openmoko Open source mobile phone running Linux and other free software, actively developed by community. CAD files and schematics included.

Gaming consoles

  • Pandora Gaming handheld console running Linux and native or emulated games.

Music Players including MP3 players

  • TRAXMOD Open source MOD music player for dsPIC/ARM microcontrollers.

PG31 GPS RS232 Dev Board

A simple RS232 example project that takes 3.3V TTL serial and outputs to a super-common RS232 connection. Insto-NMEA!

PG31 GPS USB Dev Board

A great example project using the CP2102 USB to TTL UART IC as well as some basic battery holder info.

RS232 Dev Board

A simple RS232 example project that takes all the power it needs from the serial port. Use it to power your microcontroller and communicate between serial port and microcontroller. Takes advantage of the fact that pc serial ports will accept 0-5V rather than the RS232 standard of around negative 10V to positive 10V. Very convenient - no external power required! Note that you may use either a 5.1V Zener or a 5V regulator.

RS232 RS485 USB Converter Board

Aim to build a general Converter between different Interfaces.

Number Six

"#6" (the son of Chalk Roach) is a ultra simple microcontroller development board for Atmel ATmega32 = 16MHz, 2KB SRAM, 16KB Flash

LED and POV displays

Led displays range from a battery and an LED which light up ( cool!, add a magnet and you have an led throwie ) to microcontroller led projects, either Smart Led ( Led with a microcontroller so that it blinks, reacts to the environment, or shifts color ) or Led Arrays ( or led matrix ) that do simple graphics and or play games, or POV devices where what you see depends upon you persistance of vision ( which can include some led arrays ). You can probably dig up more using these terms in google.

Our Own Projects

Off Site

Cellular Rotary Phone

An indepth breakdown of the Port-O-Rotary. Some clues to help you avoid audio problems with the GM862.

Das Brewmeister! and Fermenter Controller

Home controller

Program your appliances to operate automatically in conjunction with your weekly and daily schedule, manually turn them on/off from your PC or use the controller as a process ON/OFF controller to regulate some kind of physical variable to the desired value.

Interactive Lock Box

An interesting project using an accelerometer and capacitive touch ICs.

Motor driver (H-bridge)

atomic microscope

An atomic-resolution microscope.

  • STM (scanning tunnelling microscope)
  • AFM (atomic force microscope)


A bluetooth JTAG ICE debugger for AVR's!!!

Sort-of-Networked RFID Reader

A 125Khz RFID Reader with a simple ring network - to allow connection of multiple units to the same control computer.

Battery charger

See "Build A Smart Battery Charger Using A Single-Transistor Circuit" by Ejaz ur Rehman. But be sure to read the "Reader Comments" at the end. The suggestion to add a zener diode is a good idea.

the Open Graphics Project

the Open Graphics Project a project started by chip-designer Timothy Miller. His goal, along with the rest of the project, known as the “Open Graphics Foundation” is to make a 3D accelerated video card which is fully documented, free-licensed, and open source. See the Open Graphics wiki.

Amiga floppy project

The Amiga floppy project: designing, building, and programming an adapter to allow PCs to read from Amiga floppies. "This is really designed to be a community project(hence the blog with progress reports)."

This project is the building of an external USB amiga floppy drive controller. It sits between the USB port on a Windows PC, and a regular PC floppy drive. It will allow the PC to create .ADF images from an amiga floppy disk. This device is based on a Parallax SX28 microcontroller, uses Ramtron FRAM memory for temporary track storage, and uses another Parallax component for the USB interface.

See for the latest in the blow by blow attempts to get this thing off the ground!!


Infrared Proximity Sensor Alfa Infrared Proximity Sensor Alfa in

The Infrared Proximity Sensor Alfa is a sensor to detect objects that can reflect infrared light. It has the following characteristics.

  • Designed to detect objects that are close and can reflect infrared lights.
  • It has a Infrared Transmitter to eliminate the dependency of solar lighting. So It can be used in the night.
  • It has a Infrared Receiver that detects the closest object that reflects the infrared lights.
  • It has an incorporated voltage regulator
  • The output is a constant 5V when it is active and 0V when no detection.
  • You can change the proximity threshold with a potentiometer.

Multi-purpose Embedded System

  • This project intends to provide ideas and technical information to create a multi-purpose embedded system.
    • Information contained in this wiki should be as generic as possible (unless otherwise stated) so that the ideas and information can be portable to different hardware (e.g. 8-bit/16-bit/32-bit MCU).
    • The peripheral devices should be expandable

dsPIC33 Development Board

A development board using Microchip dsPIC33, a 3.3V based 16-bit microcontroller with DSP functions, EEPROM, ADC, PWM and communication ports of UARTs, I2C, SPI etc. Contains concise information on:

  1. Development environments (IDE)
  2. External programming methods (ICSP Programming using ICD2 Programmer)
  3. Bootloader implementation (RTSP)
  4. Software development tips based on POSIX concepts

ADuC832 Development Board


Ethernet Module

  • This project aims to develop an Ethernet Module, to be used in conjunction with a 8/16 bits embedded system such as the dsPic33F development board.

MMC Card Reader

  • This project aims to develop an MMC Card Reader, interfacing with a 8/16 bits embedded system such as the dsPic33F development board.

Modulation Plugin

  • This project aims to develop an Modulation Plugin Module, to be used in conjunction with a 8/16 bits embedded system such as the dsPic33F development board.


Some people derive an inordinate amount of pleasure from building semi-useful objects from zero-cost junk.

In the electronics field, most of the stuff built from scavenged components falls into 2 categories:

  • ham radio transmitters and receivers -- built from a few transistors, caps, resistors, and wire
  • BEAM robotics -- built from the above plus motors, solar cells, ...

According to , "I'd love to hear about where you found your 8048. Take a picture of the host that you remove it from (CD player, truck, refridgerator, whatever) and I'll put your picture on a page that chronicles our adventures sifting through the rubble."

Also see Free_From_Salvage


openEyes is an open-source open-hardware toolkit for low-cost real-time eye tracking. See the OpenEyes hardware and software and the openEyes wiki.


RepRap is an open source project to create a 3d printer or fabber machine. There is tons of information available on its website. The current iteration is a 3 axis cartesian robot with 2 extruder heads: a Thermoplastic head that extrudes plastics like HDPE, ABS, and CAPA, and a support material head that extrudes a water soluble material to support the build process.

The Biollante project is a kind of RepRap that uses a 6 axis Stewart platform. Can devices from a mechanical model library be fabbed with RapRap? The article "Self-reproducing machines" goes even further than just 6 identical parts -- it suggests that "self-reproducing machines composed of many identical microscale modules" may be a better design than the original RepRap design where just about every part is unique.

"This is the meta-problem of engineering: Design a machine that can design other machines." -- Hod Lipson[4]

Other open hardware 3d printing projects:


Challenge: Build a Wiki Device with a parts cost of no more than twenty dollars which is usable as a portable wiki. Include feature to make it compatible with a desktop or laptop computer's PersonalWiki, with a connector allowing this use. --

"hardware portable wiki for taking notes with an auto-merging functionality when you are very close to Internet or your computer." --

Could you maybe build it out of a "$12 Computer" ? "$12 Computer: Playpower Wants to Save the World 8 Bits at a Time"[5]

breakout boards

These are three boards that I designed for a specific project and found them very useful. Each of these boards uses the phoenix contact plugable terminal blocks. The 50-pin breakout board is for a 50-pin ribbon cable. The LEM breakout board is for LEM AC/DC current sensor. The power supply breakout board is for a +5v +/-15v power supply.

Free Telephony Project

Free Telephony Project

  • Embedded Asterisk IP-PBX hardware and software
  • Low cost, completely open IP-PBX hardware including FXS/FXO analog and E1/T1 interfaces, and DSP motherboard hardware. Target price of $100 for a 4 port IP-PBX.

Eyes for Open Robot

Is there a simple way for my Java application to fetch the latest camera image in an Array of pixel values?


RCAP: R/C Auto Pilot: Remote Control Auto Pilot

"The RCAP2 is a Remote Control AutoPilot] for model airplanes, cars and boats. The autopilot function can be switched off or on during flight with the flick of a switch." Uses PIC16F876A to:

  • read (servo) commands from the RC server
  • read (RS-232) GPS location from a NMEA capable GPS (with programmable goto/waypoints functions)
  • drive (servo) commands to the rudder.

RCAP Documentation at Wikibooks , and RCAP PCB layout at Sourceforge .

Wiegand reader simple controller

The PICmicro 16F628 decodes Wiegand protocol coming from card reader. If the card matches one of the 40 cards in EEPROM, it turns on the light (opens the door). Schematic and source code published under GNU terms.

ComClone2 Intercom

ComClone2 is a DIY clone of the industry-standard "party line" production intercom system as first introduced by Clearcom and now sourced by many other vendors. This intercom system is widely used in both live show(theatrical, music, etc.) and video production. Website provides complete construction information including PC board, etc.


Amiga 500 implemented with Xilinx FPGA + Freescale mc68000

USB Audio Streamer : A Homebrew USB Soundcard

This project is a homebrew 12bit 24KHz homebrew USB soundcard based on a pic 18f2550 and a few Microchip analog parts. The project is based on the Microchip USB framework, but the core audio processing is written from scratch. The card is a duel Audio 1.0 + generic interface composite device with the generic interface being handled by WinUSB. The schematic, card firmware, and host C++ software is provided.

RFDISPLAY - A Scrolling Display with RF connection to a PC

POV scrolling display with an RF connection to a mini-itx computer and weatherstation. Project is built out of 384 discrete red LEDs. Display shows time and date, sunrise/sunset time and outdoor/indoor weather.

Schematics, Board Layouts, and MPLAB C18 firmware source code is provided.


The PINGPONG-CDC project is a homebrew USB frequency hopping spread spectrum RF modem (FHSS). The modem is based on the Microchip 18F2550 and the Semtec XE1205 RF module. The module does not include a MAC or protocol layer. That is what this project implements. The project demonstrates how to write a FHSS MAC layer and use USB to interface it with a PC through CDC and WinUSB. Since the protocol is not hard-wired, it is easy to change the software to experiment with different protocols. A utility for pairing and configuring modems is included. The schematic, firmware, and host C++ software is provided.

XE1205-RNDIS : FCC Legal Frequency Hopping Spread Spectrum USB Wireless Ethernet

This is the PINGPONG-CDC project that emulated ethernet through the RNDIS driver in Windows rather then a serial cable replacement. Full source code is provided.

An acceptable third generation PostScript printer

"Ask the Guru: A Third-Generation Printer" article by Don Lancaster 1990 lists specifications for "An acceptable third generation PostScript printer." Would this be a good "open hardware" project ?

the Kestrel

The Kestrel is a grass-roots computer design employing half-way modern technology, where *EVERYTHING* is documented openly. Other goals: Instant on, (nearly) instant off. Fun to build. Fun to use. Fun to expand. The creation of a vibrant and healthy user and developer community, capable of supporting itself on both software AND hardware fronts.


A variety of "open" tools for optical and radio astronomy.

flash downloaders

Many people have published open-hardware schematics for downloading programs into the flash of various microcontrollers. m8cprogs for Cypress PSoC, various flash downloaders for Microchip PIC, etc.


The WikiNode project tries to link every wiki in the world together. Our "WikiNode" links to closely-related wiki (and their WikiNode links back).

If you want to talk about something that is not quite on-topic here at Open Circuits (say, "desktop PC case modding", or "embedded Linux programming"), our WikiNode helps you find another wiki where people love to talk about that exact topic. The corresponding WikiNode on each of those wiki helps people who want to talk about "open hardware" to discover this wiki.


arm7-oled-clock is a clock hardware/software project for a clock with a graphic organic led display running on an atmel arm7 microcontroller.

Here is the arm7-oled-clock's project page on google code.


Sun Microsystems has open sourced both hardware and software for the Sun Microsystem Laboratories Sun SPOT (Small Programmable Object Technology) Wireless Sensor Network.

This Java-based system is an ARM920T 180MHz processor, 4Mbyte Flash, 512Kbyte pSRAM and 802.15.4 radio transceiver (TI CC2420). See the Sun SPOT World website for more information. We also have an active forum.

The hardware designs can be downloaded from The content available for download (subversion) are the schematics (pdf, Altium), bill of materials (Excel), assembly drawings (pdf), fabrication drawings (pdf), PC design files (Altium) and gerber files (RS274X) for these boards.

The boards we have posted are:

  • eDemo: Demonstration add-on board for the Sun SPOT.
  • eFlash: MiniSD card reader/writer add on board for Sun SPOT
  • eProto: Prototype board with simple interface to Sun SPOT
  • eProtomega: eSPOT Prototyping board with Atmega88 processor
  • eSerial: RS232 Serial interface board for the Sun SPOT
  • eUSB-Host: USB host interface to Sun SPOT
  • eDaq: Industrial strength ADC board
  • eBones: Basic interface board application note
  • eSPOT: Main Sun SPOT board

Our wiki for the hardware is

SPOTs run Squawk, an open source Java virtual machine (VM). The download (and more information) for Squawk is The SPOT specific libraries can be downloaded from along with community applications

Open Source USB programmer

Open Programmer is an open source USB programmer for PIC micros, ATMEL micros, I2C EEPROMS, generic I2C/SPI devices. It's based on a 18F2550. Open Programmer home page.
Usbpicprog is another open source USB pic programmer for PIC 10F, 12F, 16F and 18F devices, for Windows Mac and Linux Usbpicprog


improved flashlight design

"Shake to Charge Flashlight" designed by David A. Johnson, P.E. has a sketchy outline of an improved flashlight design. "Knock-off Flashlight Trades off Light Intensity for Duration" has some further comments.

One interesting idea: "... it might be powerful enough to charge up a dead automotive lead acid battery after a few minutes of string pulling to start a car. Such a device might be small enough to fit into a car’s glove box ..."

Other Lists of Semi-Open Projects

  • UHF FM BUG with ButtonCell battery ( ) "This bug is 100% made from an old Nokia GSM phone! It operates at 434 MHz and reception can be achieved on a modified TV tuner or 70cm band HAM radio."
  • microcontroller alternatives lists a bunch of "small PCBs" (is there a better name?) designed for hacking and prototyping, that already have the processor and a few other super-common things built in ... so you don't have to start *completely* from scratch.
  • ThinkCycle "ThinkCycle is a ... non-profit initiative ... supporting distributed collaboration towards design challenges facing underserved communities and the environment. ThinkCycle seeks to create a culture of open source design innovation"
  • Are the Positron projects "open" enough to be mentioned? I especially liked the "Lasercut Acrylic Casebuilding Tutorial" .
  • Is the Vislab puck suitable for this list?
  • PICList & JAL_List free PCB contest "this will encourage people to publish designs and get more good ideas out into the real world for everyone to see." (So, are these "open" circuits?)
  • has a bunch of schematics and a web discussion forum. Are they "open" enough to mention here?
  • "Yet Another One-hand Keyboard" ( ) "The firmware included in the download lets an Atmel AVR '2313 microcontroller interpret chords and talk to a PS/2 port." -- it's not completely open, but the license allows you to immediately download, for free, lots of technical information and a license to build up to 5 of your own. Building more than 5 requires some sort of payment to license the patent on the hardware configuration. (The software appears to be open source). There seems to be an associated Yahoo mailing list. What is an appropriate way to invite John W. McKown and others on the mailing list to use a wiki such as Open Circuits to maintain a FAQ?
  • FC's Electronic Circuits ?
  • "Pandemic Ventilator Project" asks: "Does Open Source Hardware Development Work?"
  • GSM SMS Controllers ( ) "TwoWay Thing (GSM Controller v3) is a device that allows you to control appliances using SMS messages. There are also 4 inputs for connecting sensors so the device will send an alarm SMS or even call you to report an alarm condition. The device draws very little current and is being powered by phone’s battery which is a great thing. Nokia should be constantly charged or supplied with some sort of external power for long term operation."
  • Phone-call alarm alert ( ) "After programming just supply power to the device. After pressing the button "Pokreni dojavu alarma" it will start to dial (tone or pulse, depending on the jumper setup). When the phone call is succesfully established, the called party should press pound key "#" to stop the device from calling another number or again."
  • SMS Box ( ) "This device acts as interface between your microcontroller project and a GSM phone. It handles all modem data communication between the GSM phone and your micro-project. The best thing is that it decodes PDU into TEXT on the fly!"
  • GSM alarm alert - call ( ) "Alerting alarm over via GSM network"
  • Bug Labs: A startup is readying a modular, open source hardware/software system resembling a set of electronic Legos. Nov. 05, 2007 [6]
  • PIC flow meter and instrumentation modules: Sensors, Gauges, Flow meter, data logging, connected by Grundfos Pumps inc. GENIbus over RS485.
  • Raphaël Assénat has posted several electronics projects, including schematics. Several of them involve interfacing various "classic" video game controllers to USB. His "Caller Id decoder" is a nice example of adding just one more feature to something using a minimum of additional electronics.
  • Grand Idea Studio -- do these badges count as "open circuits"?
  • "HOWTO set up a molecular biology lab for less than $1000" Posted by Cory Doctorow 2009

other project sites or links to projects

May or may not be open, not much review material here, noted for the record, may be promoted in the future if they are outstanding in any way.