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 | 1 comment

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.

Posted in Free PCBs | Tagged | 1 Comment

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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Schlage smart door lock hack/teardown

in Teardowns by DP | 0 comments


Teardown and hacking of Schlage smart door lock by Felix Rusu of LowPowerLab:

As the title suggests it’s a smart door lock with a for coded entry and is based on “Iris” which in turn uses ZWave RF wireless technology (made by Zensys), a closed source patented protocol+hardware stack that is OEM-able to automation system makers who want an “off-the-shelf” wireless stack to integrate into their product.

Check out the video after the break. Continue reading →

Making an FPV system

in project logs by DP | 0 comments


Check out Elpis’ FPV system in the project log forum:

I’ve started flying quadcopter and tricopters a few months ago and now I am going towards FPV (First Person View). So, instead of having all the cables around and the different components on top of the other I put the receiver inside the small LCD screen and connect everything internally. The result is compact and most of all cheap!
I am sure that I could do a better job with the cables!
Latter, I will include a video recorder, I will add a 3.5mm jack for the second output of the receiver and I am designing a diversity receiver as well (again it will go inside the plastic cases of the LCD screen). The first input of the receiver will use the already available circular polarised antenna and the second input will use a panel type or helical antenna!
And yes! Some DangerousPrototypes stickers making this prototype more “dangerous” and an official entry into the makers/hackers community!!!

For more information on this build, visit Embeddedday.


Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 60 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 →

Posted in Free PCBs | Tagged | 60 Comments

App note: Using the enable Pin in a linear regulator as a voltage supervisor

in app notes by DP | 0 comments


Clever way using linear regulator’s enable pin implementing a voltage supervisory circuit control, an app note(PDF) from ON Semiconductors.

The combination of a voltage regulator and a voltage supervisor, is a popular circuit configuration. The addition of the supervisor ensures that the regulated output turns on and off at sufficient input voltages, as well as giving the system the luxury of a safe and ordered startup.

App note: using MOSFETs in load switch applications

in app notes by DP | 1 comment


App note(PDF) from ON Semiconductor.

The load switch is controlled by the system, and connects or disconnects a voltage rail to a specific load. By turning unused circuitry off, the system as a whole can run more efficiently. The load switch provides a simple means to power a load when it is in demand and allows the system to maximize performance.

App note: 868 MHz, 915 MHz and 955 MHz inverted F antenna

in app notes by DP | 0 comments


868 MHz, 915 MHz and 955 MHz inverted F antenna (PDF) application note from Texas Instruments:

This document describes a PCB antenna designed for operation in the 868 MHz, 915 MHz and 955 MHz ISM bands. This antenna can be used with all transceivers and transmitters from Texas Instruments, which operates in these frequency bands. Maximum gain is measured to be −0.12 dB and overall size requirements for this antenna are 43 x 20 mm. Thus this is a medium size, low cost antenna solution.
Figure 1 shows a picture of the board being used to develop and characterize this antenna. The board is pin compatible with CC1110 EM and is equipped with two LEDs, a push button, a 10-pin debug connector and a 2-pin power connector for test and characterization purpose.

App note: Minimizing power consumption when sensing switch inputs

in app notes by DP | 0 comments


An app note (PDF!) from Renesas  on how to minimize power consumption when sensing switch inputs

A switch input is one of the simplest interfaces to an MCU. However, when very low power designs are needed the pullup or pulldown resistor for the switch can draw a significant current. If the switch input is a momentary switch the current flow is very short so it is rarely significant. However, if the switch input is a door switch or level sensing switch
or any other switch which may remain in the active state for a relatively long time the energy used must be considered
Most of the discussion that follows gives examples for pull-up devices with the switches, the same principles apply for pull-down components. Also all the discussions assume that the EVdd = Vdd (all ports powered from the same supply voltage).


Arduino Library for Freescale’s MMA7361 3 axis accelerometer

in Arduino, library by DP | 0 comments


Rohit Gupta wrote a basic library for using MMA7361 3axis Accelerometer with Arduino, that is available at Github:

This library helps you to easily play with the almost universal 3 axis accelerometer available in most Hobby markets that is based on Freescale’s MMA7361.
In order to get in working you have to pull-up the sleep pin using a 10K resistor to the 3.3V pin. All other connections are labelled.

Via the contact form.

RUFS, an open source Arduino based robotic farm

in DIY, robotics by DP | 0 comments


Paul Langdon over at BLT Robotics wrote in to let us know about a cool open source project the vertical hydroponic farm, an instructables here:

We call our project RUFS, for Robotic Urban Farm System

  • A vertical hydroponic garden
    -Allowing for high density yields and shorter growth cycles
    -Reducing resource consumption – water, fertilizer and space
    -Labor saving – no weeds or soil to till
    -Higher consistency of crops with great tasting results
  • Maintained by micro-controllers (Raspberry Pi & Arduino)
    -Watering cycles – monitor and auto refill levels
    -Plant nutrients and pH – monitor and correct
    Temperature monitoring
    -Air Circulation & Lighting controls (for indoor operation)
  • Smart and Connected
    -Farm Controller App for smartphone, tablet and pc
    -Get notified when the system needs a refill
    -Alerts when something isn’t running as expected

Via the contact form.

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 1 comment


Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes 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 | 1 Comment

Week in (p)review November 14, 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

Lo-Fi SES: Hackable 8-bit chiptunes instrument

in open source by DP | 0 comments

Here’s an interesting open source project on Kickstarter the Lo-Fi SES (Sound Entertainment System) by Assorted Wires:

The Lo-Fi SES (Sound Entertainment System) makes the process of playing an instrument easy by providing a video game controller interface for the lo-fi instrument. The d-pad allows you to change or record tracks, the buttons play the various sounds, and the l/r dials dynamically effect the frequency of the sounds as you are playing them.
A combination of things make this instrument unique. It is a fully open (hardware and software) audio platform, compatible with the Arduino ecosystem, and uses an innovative cart-based expansion system. Yay cartridges!!! The instrument is super approachable for level 1 musicians, but it is designed to be fun no matter what level you are at. The higher-level users can hack on the software via a “USB: a Link to the Hack” cart or even design a custom cart themselves. (I have a strong desire to see someone create a ridiculous rumble pack. You could make it rumble to the beat for some superfluous haptic feedback.) Also, the USB cart solves a common complaint for other lo-fi instruments: it allows you to swap out the sounds with ones of your own design!

SatNOGs wins the 2014 Hackaday Prize

in contest by DP | 0 comments


Today Hackaday announce the 5 top winners!  SatNOGs wins the 2014 Hackaday Prize:

The Grand Prize winner of the 2014 Hackaday Prize is SatNOGs. The project is a thrilling example of the benefits of a connected world. It opens up the use of satellite data to a much wider range of humanity by providing plans to build satellite tracking stations, and a protocol and framework to share the satellite data with those that cannot afford, or lack the skills to build their own tracking station. The hardware itself is based on readily available materials, commodity electronics, and just a bit of 3D printing.

The awarding of the Grand Prize caps off six-months of productive competition which started in April with a first round reaching to more than 800 entries. Once the field had been narrowed and sent on to our judges the narrowed it to just 50 projects vying for a trip into space (the grand prize), industrial-grade 3D printer and milling machine, a trip to Akihabara electronics district in Japan, and team skydiving.

Congratulations to all 5 top winners!

Continue reading →

Tektronix RSA306 IF frequency verification

in measurement, testing by DP | 0 comments


KF5OBS writes:

After posting the teardown video of the Tektronix RSA306 USB 3.0 Spectrum Analyzer on my YouTube channel, someone asked me to verify that the IF sampled by the Linear Technology 14-Bit / 125 Msps ADC is really at 140 MHz. Using the Tektronix MDO4104B-6 and a passive RF probe, I gladly did so.