Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 39 comments


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 →

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App note: Digital sound recorder with AVR and DataFlash

in app notes by DP | 0 comments


An app note from Atmel, digital sound recorder with AVR and DataFlash (PDF!):

This application note describes how to record, store and play back sound using any AVR microcontroller with A/D converter, the AT45DB161B DataFlash memory and a few extra components.
This application note shows in detail the usage of the A/D Converter for sound recording, the Serial Peripheral Interface – SPI – for accessing the external DataFlash memory and the Pulse Width Modulation – PWM – for playback. Typical applications that would require one or more of these blocks are temperature loggers, telephone answering machines, or digital voice recorders.

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Configure your WR703n with a switch (or two)

in hacks, wireless by the machinegeek | 0 comments

Martin Melchior has been experimenting with switch-selectable configurations for a TP-Link TL-WR703n router. The setup allows for quick changes in configuration dictated by changes in location or circumstances. It allows the router’s use as a Ethernet to WiFi bridge (Access point), since it’s handy to have your own WiFi at a friend’s house or hotel; or to connect a wired Ethernet device to your home WiFi through the router (configured as a WiFi client).

Details can be found on Martin’s website.

Via the contact form.

68 Katy – 68000 Linux on a solderless breadboard

in DIY, hacks by DP | 1 comment


Steve Chamberlin of Big Mess o’ Wires has written up documentation on his awesome 68 Katy project,  a 68000 Linux on a solderless breadboard:

Here’s a look at the final version of the hardware. It took about a week to assemble and wire up all the parts on a solderless breadboard. The heart of the system is a Motorola 68008 CPU, a low-cost variant of the more common 68000, with fewer address pins and an 8-bit data bus. The CPU has 20 address pins, allowing for 1 MB of total address space. It’s paired with a 512K 8-bit SRAM, and a 512K Flash ROM (of which 480K is addressable – the remaining 32K is memory-mapped I/O devices).

Check out the video after the break. Continue reading →

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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.  The coupon code usually go to Facebook ‘Other’ Messages Folder .  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

Review: GoPro hero budget camera vs the SJ4000

in gadget by DP | 0 comments

Mat from Techmoan writes:

In this review we’ll find out exactly what you get for your money and whether this stripped down GoPro is worth the price premium over the SJ4000. I’ll run a few head to head video quality tests and list what features each device has in its favour. Ultimately though its down to you to choose the camera that you prefer. I’ll present the evidence but you have to make the decisions.

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Automatic plant watering system using AVR(Atmega16) Microcontroller

in AVR, sensors by DP | 3 comments


Here’s an automatic watering system using AVR from Gadgetronicx:

Primitive irrigation systems possess many drawbacks as it fails to conserve water and human energy. So introducing Automation in it can help us to overcome these drawbacks and pave way to conserve water. This can be done with a simple Soil moisture sensor and a Microcontroller, AVR in our case. You can try out this system to automate watering the plants in your home at affordable cost.

Small USB IR Toy case

in cases by DP | 0 comments


This small IR Toy case by GHPS is up on  Thingiverse:

Sick of beige cases? Then print it in blue, red, black – or the color that you want…
The irToy by dangerousprototypes is a small, universal infrared controller for the USB bus. It can receive and send arbitrary ir signals – and is completely open source.
But comes quite naked without any case.
This enclosure is as small as can be allowing it be attached to the screen or desktop case. The front provides posts for an ir foil to shut the box close and still receive/send ir signals.

More cool DIY cases here.

You can get IR Toy v2 for $22.05, including world wide shipping.

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Self-Balancing Raleigh Chopper

in Arduino, hacks by DP | 0 comments


XenonJohn posted detailed instructions of how to make this Self-Balancing Raleigh Chopper. He writes:

Data from the IMU is read by the Arduino Mega 1280. I use a Mega 1280 because they are a lot cheaper online than the 2560, and about the same price as an Uno. They have several hard wired serial outputs which means I can conveniently use one of these to send motor control data to the Sabertooth 2 x 25 Amp power controller, and another to send data to the serial-LCD screen. The Deadman switch and steering buttons (actually brake levers from children’s e-scooters) when pressed will connect their respective Mega pins to ground. The deadman is for safety, if you let go of it all power to the motors will stop after half a second. Digital Pin 12 is connected to an LED. This LED stays lit on startup and goes out after a few seconds when the machine is ready to be brought “level” at which point it will start to balance itself. The potentiometer in the diagram is actually on the left handlebar and is a Magura 5K potentiometer “twist-grip” throttle handle designed for electric vehicles. Turning it makes the machine lean forwards a little, and so it starts to roll forwards. Let it spring back and machine will lean backwards a little and slow down. It makes a very effective method of controlling speed (as well as simply leaning like you would on a Segway).

Via Hacked Gadgets.

Check out the video after the break. Continue reading →

1clickBOM, a browser extension to quickly add components to shopping carts

in tools by DP | 1 comment


Kaspar of Monostable shared this helpful purchasing tool the 1clickBOM, a browser extension to quickly add electronic components to shopping carts:

1clickBOM is purchasing tool that let’s you keep one bill of materials (BOM) for items from multiple retailers. It’s a browser extension that fills your online shopping carts for you. To add items to 1clickBOM you simply paste from a spreadsheet or visit an online .tsv file.

Which retailers?
Currently supported retailers are:

Code is available on Github.

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Adrian Jones’ Dirty PCBs review

in by DP | 7 comments



Why did you choose Dirty PCBs?  Was there something else you liked about them?  Adrian Jones over at WoodUino tried it out:

As you can see, I chose a white coating for the boards but they offer many colours at no extra cost. The plating is excellent and the boards soldered easily. The component silk-screen is clear but all over the place – my fault because I didn’t bother to take the time to pretty it up.  The boards are clean and tidy and look very professional.

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Viewing a VHS tape using RTL-SDR and TV Sharp software

in hacks, RF, SDR, software by the machinegeek | 4 comments

Here’s a different and unconventional way to view a VHS tape (as if VHS tapes aren’t considered unusual enough today). DogsRNiceMineCraft posted this video on YouTube showing video received using an RTL-SDR dongle.

I got a VCR today and wanted to see if I could receive the signal from the RF out using TV sharp. I wrapped the antenna cord that came with my dongle around the RF out cable from the VCR, but it only works if the cable is barely touching the RF out port.

An unusual proof of concept which could have other applications.

The TV Sharp program referred to by the video’s poster appears to be available for download from (Note: website primary language is Italian.) It allows reception of certain analog video signals using the RTL-SDR.

#FreePCB via Twitter to 2 random RTs

in Free PCBs by DP | 0 comments

KHOS-2-3-4-5-6P 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 it every Sunday, right here on the blog
  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs will be your friend for the weekend

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Check out how we mail PCBs worldwide video.
  • We’ll contact you via Twitter with a coupon code for the PCB drawer.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

An op-amp based Electret Condenser Microphone Preamp for microcontrollers

in hacks by DP | 0 comments


Davide Gironi writes:

This is an op-amp Electret Condenser Microphone Preamp board design for the use with microcontrollers ADC.
For the NPN version of this board, an for more information about microcontroller ADC and microphone input, please refer to this page
The proposed circuit is just a revision of a pretty usually op-amp electret mic preamplifier.
The selected op-amp is the TLC272, because it can be drive in single rail operation, it’s common mode input range, and has good noise performance. Also other op-amp could work. The op-amp is configured in inverting mode.

Check out the video after the break. Continue reading →

USB Infrared Toy free PCB build

in builds by DP | 0 comments


James built a USB IR Toy v3 free PCB.  With the USB IR Toy you can use a remote control with your computer, view infrared signals on a logic analyzer, capture and replay remote control buttons.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

You can get IR Toy v2 for $22.05, including world wide shipping.

Via Twitter.


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