The DigiRule

in tools by DP | 1 comment

The DigiRule

Brad has designed a cool binary PCB ruler, The DigiRule:

So I made the DigiRule! – The DigiRule is a 15cm (6″) ruler with which is marked in binary digits rather than decimal. It has a number of built in digital functions including:

  • Logic Gates
    -NOT Gate (Inverter)
    -OR Gate
    -AND Gate
    -XOR Gate
    -NOR Gate
    -NAND Gate
    -XNOR Gate
  • Flip Flops
    -SR Flip Flop
    -JK Flip Flop
    -Toggle Flip Flop
    -Data Flip Flop
  • Four bit binary up/down counter

It is powered by a single 3V CR1220 button battery and the brains of the unit is a PIC 18F43K20 microcontroller (which is a greatly over powered device for such a simple task – but they are cheap!) The functions listed above are controlled by nine surface mount push buttons and has twenty three surface mount LED’s to show the status of the inputs and outputs.

Project info at Brads project site.

Check out the video after the break.

Continue reading →

Posted in tools | Tagged , | 1 Comment

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 2 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 | 2 Comments

A connected lamp to wake me up

in LEDs by DP | 0 comments


Limpkin writes, “I’ve always wanted to play with these 10W RGB LEDs!
So for some reason I bought 2 IKEA lamps at a flea market. As IKEA furniture has a long history of being hacker-friendly, I figured they shouldn’t be an exception to the rule.
My plan? Fit a few 10W RGB LEDs in there together with an ESP8266 to use the final result as an alarm clock.”

Project info at Limpkin blog.

Posted in LEDs | Tagged , , | Leave a comment

Implementing a multi-peripheral controller using a tiny mixed-signal FPGA

in FPGA by DP | 0 comments


Max Maxfield over at the writes:

As you may recall from previous columns, I tend to think of Silego’s
GPAK chips as being super-small mixed-signal FPGAs that you can
literally design and program in just a few minutes, and that cost only a
few cents each.

Well, the folks at Silego were so excited by the interest my columns generated within the and communities that they decided to offer 25 development kits for free (see Want a free Silego GPAK4 mixed-signal FPGA development kit?).

The idea was that and community members would email me to excite me and delight me with descriptions of the amazing hobby or work projects they might use GPAK4 devices for, thereby convincing me that they deserved to receive one of these little beauties.

Two weeks later, I sauntered into the Pleasure Dome (my office), ensconced myself in my Supreme Commander’s Chair with its super-soft cuddly cushion, and selected the 25 entries that most ignited my imagination and whipped my creative juices into a frenzy (see 25 Free Silego development kits will soon be winging their way).

After this, things went quiet for a while, until earlier today when I heard from one of the lucky recipients, J.R. Stoner, who is principal engineer (and self-described “chief bottle-washer”) at the Bifrost Development Group.

In his email, J.R enclosed the .gp4 (GPAK4) design file associated with his latest project, which is a multi-peripheral controller (click here to download a compressed ZIP file containing the .gp4 design file along with the images presented below). The schematic for the portion of the design featuring the GPAK4 chip (a 20-pin SLG46620 device) is shown below.

More details at Bifrost Development Group and

PIC24 bedside table alarm clock

in clock, project logs by DP | 4 comments


Markus Gritsch posted pictures of his PIC24 bedside table alarm clock in the project log forum:

Another year, another clock, but for the first time for my alarm clocks. I am not using an MSP430 but a PIC24 instead. Standby current is with 5.5 µA only slightly higher than that of my MSP430 based ones. Time keeping is done using the RTCC pheripheral, which I also used for the first time.
It can be seen in action in this YouTube video
Friendly green digits :)
And of course it has a LiFePO4 battery on its back, being charged every few years using my new USB charger.
A photo transistor is also included to dim the display in the dark. Much nices to the eyes when checking what time it is in the middle of the night.

Source code and schematic are available in the forum.

Check out the video after the break. Continue reading →

Posted in clock, project logs | Tagged , | 4 Comments

Software Serial Modbus Master over RS485 transceiver

in hacks by DP | 0 comments


Colin writes:

We like cheap, well-made temperature controllers. Sure, we can make our own, but for a modest sum we can get a nice NEMA-rated package capable of reasonably complex logic with a communications interface. The Love 4C and 16C controllers can both be had for <$100 fit this description and make dependable control and higher-level monitoring possible.
The downside is that the interface is modbus over RS485, which requires a driver chip such as the Maxim RS485 which will translate to serial for control over a UART or other serial interface. This is not a killer, as you can get a nicely laid out RS485 chip from Sparkfun for $10, or make your own.
The reason for this piece is that all RS485 code I could find was designed for use with the hardware serial UART on microcontrollers such as Arduino or clones such as the Moteino. Because I typically use the UART for communication to a Pi or to a debug console, and the 328P I typically use has only one, this was not an option. To make it work over a few digital pins, it is actually quite easy to use the SoftwareSerial library to make this happen.

More details at CupidControls site.

Just good enough 10 MHz reference

in hacks by DP | 0 comments


Sverre Holm  writes:

Some time ago I noticed that the Ublox Neo-7M GPS has a 10 MHz output which is locked to the GPS system’s accuracy. Most people kept saying how useless it was due to excessive jitter unless it was cleaned up with a phase locked loop of some sort. But at the same time I installed the reference input for my Elecraft K3 (K3EXREF). It enables the K3’s frequency to be locked to an external 10 MHz reference. What struck me was how its function was described:

  • The frequency of the internal oscillator of about 49.38 MHz is continuously measured and averaged, obtaining a value to the nearest 1 Hz.
  • The K3EXREF does not phase lock the K3’s reference oscillator and the external 10 MHz source has no impact on the K3’s phase noise performance.

This got me wondering if the Neo-7M would be just good enough as a reference and that all the averaging internally to the K3 would take care of the jitter.

Posted in hacks | Tagged , , , | Leave a comment


in DIY by DP | 0 comments


Oakkar7  has been working on his DIY CNC machine:

When Arduino meets PIC, csCNC was born. Before milling, I tested some jobs, text, drawing and also a sketch. See the video of csCNC drawing a sketch.
This is my DIY CNC machine which built for hobby and personal tool need. The designe is inspired by many CNC machines arround the net and used opensource Arduino based CNC controller name “grbl” and PIC based motor controller named “Linistepper”. I use GRBL Controller 3.0 for PC software and it worked well for the first run without tweaking too much.

Project info at Oakkar7 blog.

Check out the video after the break.

Continue reading →

Posted in DIY | Tagged | Leave a comment

Beaglebone Black music box project

in project logs by DP | 0 comments


Brian’s Beaglebone Black music box project:

 I would like to thank Miero for his hard work on the linux I2S driver for Beaglebone Black’s SOC without the driver this project would not exist.
You can see the design in its enclosure here below and in the following video
The design is essentially complete and tested as of 7/12/2015. Software and hardware are fully functional.

Via the forum.

Check out the video after the break.

Continue reading →

LiFePO4 charger

in project logs by DP | 5 comments


Markus Gritsch shared his LiFePO4 charger project in the forum:

Since I really like using LiFePO4 AA and AAA batteries in some of my projects, I finally gave in and built a dedicated charger for them.
Previously I used a lab power supply to mimic the constant current/constant voltage charging curve, which worked also fine. But after seeing Patrick Van Oosterwijck nifty LiFePO4wered/USB™, I thought it would be a bit more convenient to charge these batteries using USB.

Via the project log forum.


#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.

DIY model train controller project

in DIY by DP | 0 comments


Ron Hoffman over at Gadgetronicx has written up an article on his DIY model train controller project:

Model trains are fun toys which every one of us used to play with in our childhood. Many sophisticated and attractive model trains are available in the market now a days yet the basic principle in build a controller for it remains the same. I built a Model train controller which is equipped with Acceleration and deceleration control using the PWM technique. And also Forward reverse button to control the direction.

Project details at Gadgetronicx project page.

Posted in DIY | Tagged , | Leave a comment

Open Inverter, an open source micro-solar inverter

in open source by DP | 0 comments


Ken Boak has been working on an open source micro-solar inverter project:

We wanted to make a design that uses readily obtainable N-type FETS and an Arduino (more strictly a ATmega328P-PU on a breadboard) to generate the PWM signals and provide simple circuit protection, and load sensing. With the PWM signals generated in firmware it can easily be modified for 50Hz or 60Hz operation, either 115V or 230V operation and a wide range of battery input voltages.
We imagined that the final design could consist of an Arduino, an “Inverter Shield” containing FETs and driver ICs configued in a H-bridge and some voltage and current monitoring circuits. To make the inverter a 12V or 24V battery (or PV panel) and a 12V (or 24V) torroidal transformer would be added.

Project info at Ken’s Sustainable Suburbia blog.

DIY 110v temperature controlled soldering station

in project logs by DP | 0 comments


Mike Doughty over at PCBSmoke shared his DIY 110v temperature controlled soldering station in the project log forum:

This post shows how to build a do it yourself 110 volt soldering station. It is a step by step guide that shows how to convert a regular plug-in soldering iron into a temperature controlled unit.
It is an easy project that is inexpensive to make and requires only basic skills to build. It is made from off the shelf parts that can be obtained from online suppliers plus a few parts from a local hardware store. It is inexpensive to build plus it makes a shop tool that is on par with some commercially available units.
A thermocouple was inserted into the soldering iron at the rear of the heating element and the power cord and AC plug were replaced with a flexible multi-conductor cord and 4-pin DIN connector.

Project info at PCB Smoke site.  Via the forum.

Check out the video after the break.

Continue reading →

App note: Ultrasonic sensing for water flow meters and heat meters

in app notes by DP | 0 comments


TI’s application note on Ultrasonic sensing for water flow meters and heat meters (PDF!)

Ultrasonic flow meters are gaining wide usage in commercial, industrial and medical applications. Major benefits of utilizing this type of flowmeter are higher accuracy, low maintenance (no moving parts), noninvasive flow measurement, and the ability to regularly diagnose health of the meter. This application note is intended as an introduction to ultrasonic time-of-flight (TOF) flow sensing using the TDC1000 ultrasonic analog-front-end (AFE) and the TDC7200 picosecond accurate stopwatch. Information regarding a typical off-the-shelf ultrasonic flow sensor is provided, along with related equations for calculation of flow velocity and flow rate. Included in the appendix is a summary of standards for water meters and a list of low cost sensors suitable for this application space.

App note: Passives aren’t really So Passive: Resistors

in app notes by DP | 0 comments


Part 2 of the “Passives aren’t really so passive” series app notes from Maxim Integrated, this time about resistors and their tempco and tolerance degeneration that need to be considered. Link here (PDF)

Passive components don’t draw power but even resistors can, and modify signals in unexpected ways. A resistor’s reaction to temperature, voltage, and signal frequency can often catch the inexperienced engineer by surprise. Tolerances may not be as they seem and simple resistors may provide nonlinear signal response, introducing harmonics where there were none.

Free PCB Sunday: Pick your PCB

in Free PCBs by DP | 44 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 | 44 Comments

App note: Passives aren’t really So Passive: Capacitors

in app notes by DP | 0 comments


Interesting app note from Maxim Integrated on small parasitic effects of capacitors that makes them less passive. Link here (PDF)

Active components like transistors and integrated circuits change signals using energy from the power supply. Conversely, passive components like resistors, capacitors, inductors, and connectors do not consume power or so we like to assume. However, passive components actually can and do change the signal in unexpected ways because they all contain parasitic components.

This application note, the first in a 3-part series, discusses parasitic capacitance.

Backdoor uPWM Hack on Photon for Infrared signals using UART

in hacks by DP | 0 comments


The crew from AnalysIR has written up an article on Backdoor uPWM Hack on Photon for Infrared signals:

Since we received our Photon several months ago it has been difficult to find a working example of Hardware PWM on the Photon (suiteable for IR signals). Initially, we ported our softPWM approach to the Photon, which is excellent. However, we figured it must be possible to use at least one of the spare UARTs on the Photon to achieve our goal. So first we started prototyping on the Arduino and quickly got a working example with some limitations – only 40 kHz and 33 kHz carrier frequencies were possible with the UART without delving into the registers a bit more. Then we moved the code over to the Photon, leveraging our previous softPWM examples, upgraded with the Arduino code – EUREKA! The Backdoor uPWM Hack on Photon for Infrared signals.

More details at AnalysIR blog.

Free PCB coupon via Facebook to 2 random commenters

in Free PCBs by DP | 4 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 | 4 Comments