Free fun flexible watch

in clock, open source by DP | 0 comments


F*watch team writes:

F*watch is a fully open electronic watch project featuring an integrated GPS receiver. The development started at CERN as an after-work project to make a special present for a retiring colleague who likes hiking and timing. The full design (electronics, mechanics and software) is available under free licenses and the design is exclusively made with free tools.

  • Sensors

-Pressure sensor
-Ambient light sensor

  • I/O

-128×128 pixels LCD with backlight
-Micro-USB connector, 4 Buttons
-Buzzer, vibrating motor
-MicroSD memory slot

  • Various

-500 mAh Lithium-ion battery, fuel gauge
-4-layer PCB

Via Hacked Gadgets.

Digitally controlled bench PSU project update

in DIY, power supply by DP | 0 comments


Yet another update on Bertho’s digitally controlled bench PSU project we covered previously:

Did some test-bed assembling today and did a dry-test of the power board.
The good news… the power board did not blow up ;-)

The aux PSU for +/-12V analog and the 5V logic supply switcher is working as it should. The power board is able to supply the control board as far as I can see. Haven’t done any in-depth testing, but it looks good. The main low voltage AC inlet is also functional and the default of the power switcher is correctly off. The DC voltage after the rectifier was tested to 42V DC and no sparks or smoke were detected.
With the preliminary tests complete, I have now a small test-bed to continue working. The setup has the control board with LCD, 2 encoders (+ push switch) and 3 LEDs. All is powered from the power board aux supply…

App note: Power-supply solutions for Xilinx FPGAs

in app notes by DP | 0 comments


MAXIM’s power solution for Xilinx’ FPGAs. App note here (PDF!)

Field-programmable gate arrays (FPGAs) are used in a wide variety of applications and end markets, including digital signal processing, medical imaging, and high-performance computing. This application note outlines the issues related to powering FPGAs.


Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 86 comments

buspiratev383 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 get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Continue reading →

Posted in Free PCBs | Tagged | 86 Comments

App note: Power supplies begin the circuit foundation, taming switching power-supply layout

in app notes by DP | 0 comments


A power supply design app note from MAXIM.

This article outlines power, ground PCB, and system layout hints and kinks. It includes an overview of using power, ground star points, and multifrequency power decoupling. It also shows how to control the component placement to minimize the size of the high-current switching loop.

App note: High speed amplifier techniques

in app notes by DP | 1 comment


An old but interesting app note (PDF!) from Linear on high speed amplifier techniques:

Most monolithic amplifiers have been relatively slow
devices. Wideband operation has been the province o
discrete and hybrid technologies. Some fast monolithic
amplifiers have been available, but the exotic and expensive
processing required has inflated costs, precluding
widespread acceptance. Additionally, many of the previous
monolithic designs were incapable of high precision and
prone to oscillation or untoward dynamics, making them
Recent processing and design advances have made inex-
pensive, precision wideband amplifiers practical. Figure 1
lists some amplifiers, along with a summary of their
characteristics. Reviewing this information reveals ex-
traordinarily wideband devices, with surprisingly good DC
characteristics. All of these amplifiers utilize standard op
amp architecture, except the LT1223 and LT1228, which
are so-called current mode feedback types (see Appendix
H, “About Current Mode Feedback”). It is clear that the raw
speed capabilities of these devices, combined with their
inherent flexibility as op amps, permit a wide range o
applications. What is required of the user is a familiarity
with the devices and respect for the requirements of high
speed circuitry.

Bus Pirate smart card shield

in Bus Pirate by DP | 0 comments


Bus Pirate smart card shield by Yaehob:

Tired of playing with wires, breadboard and so on to interface synchronous smart cards with bus pirate, I made a kind of shield. Thank you Arduino for teaching me this way of thinking :-)
Bill of materials

  • 1x breadboard solder
  • 1x smart card socket (e.g. this one, this one, or ebay : here and here)
  • 1x female header [2X5]
  • 3x pull-up resistors [2kΩ-10kΩ] (I added a piece of wire to connect them, or not)
  • Wire

Get your own handy Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 3 comments


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.

Don’t forget there’s free PCBs three times every week:

Continue reading →

Posted in Free PCBs | Tagged | 3 Comments

Week in (p)review October 17, 2014

in week in review by DP | 0 comments


Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

  • Free PCBs via Facebook on Friday
  • App notes on the weekend
  • Free PCB Sunday
  • Free PCBs via Twitter on Tuesday
  • Weekly roundup and preview every Friday

DirtyPCB Yellow-Panel microgameboy

in by DP | 2 comments

In this video Stijn Kuipers demonstrates his Yellow-Panel microgameboy:

The recent paneling experiment resulted in a nice new addition to our prototyping toolbox.
The yellow panel contains:

  • Wolfsom SMT microphone breakout with small amplifier
  • QFN24-to-dip adapter
  • Freescale K20 TFT backpack (enhanced Teensy3.1 without the bootloaderchip)
  • Freescale KL02Z DIP breakout with microphone
  • USB-testpoint board in USBstick form
  • 0.49″ I2C OLED breakout board
  • 3.3v MIDI IO board
  • KL02Z micro-gameboy with 0.49″ OLED, microphone, switches and battery.
  • A keychain
Posted in | Tagged , | 2 Comments

DIY USB-Oscilloscope in a matchbox

in DIY, oscilloscope by DP | 0 comments


ajoyraman posted a tutorial on how to make a DIY USB-matchbox oscilloscope,  an instructable here:

In order to economize on the cost of an enclosure while still providing an aesthetic unit the Aj_Scope2 is enclosed in a large size cardboard matchbox enclosure.
The USB connection to the PC is on one end while the Audio-Jack for the signals to be monitored is on the other.
A ‘Busy’ LED is provided on one corner at the top and a ‘Reset’ switch is provided diagonally opposite.
The ‘Reset’ switch provides a restart of the micro-controller is the worst-case of hang-up. This typically occurs when the operator selects a trigger threshold which is out of limits with respect to the waveform being observed. If the Aj_Scope2 is operated correctly this switch is seldom used.

DIY LM1876 dual 20W audio power amplifier

in DIY by DP | 1 comment


An audio power amplifier based on LM1876 from Electro Labs:

We are building another enjoyable weekend DIY project. This is an audio power amplifier based on LM1876 which can deliver up to 20W per channel into 4 or 8 ohm load and guarantees less than 0.1% THD + N (Total Harmonic Distortion + Noise).
The amplifier is powered by -15 0 15 VAC symmetrical supply. The full bridge diode rectifier and the smoothing capacitors convert the AC input to ±21 VDC which is used to power LM1876. The inductors on the AC input line reduces the noise arising from the mains line.

Via Electronics Lab.

Posted in DIY | Tagged , , | 1 Comment

Measure audio level using root mean square on Spark Core

in library, measurement by DP | 0 comments


Davide Gironi writes:

A library to retrive RMS and Spl value from an audio input.
This library reads data from an ADC pin and returns the RMS value of the input simply using RMS avarage.
The root mean square (abbreviated RMS or rms), also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity.
Here is simply implemented by getting samples, for each of them making the root, then the mean for all the collected samples, and finally square the result.

Code is available on GitHub.

Nokia 5110 screen module with PIC microcontroller and Oshonsoft

in library, PIC by DP | 0 comments


Chris Holden made a font library for a Nokia 5110 display using a PIC microcontroller and Oshonsoft. He writes:

Having left the 1980′s behind, we decided to write our own “libraries” to write text onto the Nokia 5100 display, using a PIC microcontroller. The code below was written for a 16F877a (because it was the first chip we found already on a breadboard, with a programming header connected) but would work equally well on any PIC microcontroller with enough RAM for the font table.

Minimalism AVR development board

in AVR by DP | 0 comments


Baoshi of DigitalMe wrote an article detailing his minimalism ATTiny2313 development board build:

The AVR chip I’m talking about is Atmel ATTiny2313, in SOIC-20 package. To make the development board, I bought some 28 pin SOIC/SSOP to DIP adapters. These adaptors usually come in double sided design. Corresponding pins on both sides are connected via the plated through holes at edges.
I made a 2×3 AVR programming header by pulling off pins (longer ones) from a double-row right angle pin header and reinsert them into the plastic base. A needle nose pliers is very handy for this purpose.

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Controlling appliances using text messages

in AVR by DP | 0 comments


A GSM remote control project designed by Vassilis Serasidis:

Two years later I built another one remote control based on GSM module. I choose the GM-47 sony-ericsson module because it was very easy to handle it via AT commands. Moreover, the price was low enough for experiments. Finaly, I decided to release the source code under GNU General Public Licence V3  If you don’t agree with the terms please DO NOT download or use any part of this project (schematic diagram, source code, hex code, PCB, etc).

Via Embedded Lab.