Monday, October 3, 2016

New Book: The Citizen Scientist's Guide to using the Arduino & Raspberry Pi

Our new book is online, a chapter at a time. We have a dozen chapters in various stages of proofing and testing, and have the first 3 uploaded and available at, so check them out, and leave us feedback on thoughts, problems, ideas, etc.

Posted chapters will be improved and added to and new chapters added, so keep coming back for more.

Saturday, October 1, 2016

Two Arduinos Become One

It was announced today that Arduino LLC (aka and Arduino srl (aka will rejoin to become one Company.
Massimo Banzi and Federico Musto took the stage at the New York Maker Faire to announce the good news, and the Arduino team demonstrated its products.
At the end of 2016, the newly created “Arduino Holding” will become the single point of contact for the wholesale distribution of all current and future products, and will continue to bring tremendous innovations to the market.
In addition, Arduino will form a not-for-profit “Arduino Foundation” responsible for maintaining the open source Arduino desktop IDE, and continue to foster the open source movement by providing support for a variety of scholarships, community and developer initiatives.
Massimo Banzi, Co-Founder of Arduino LLC, said, “Today is one of the best days in Arduino history. This allows us to start a new course for Arduino made of constructive dialogue and non-disruptive innovation in the Education, Makers and IoT fields. The Arduino Foundation will allow us to champion the core values of the Arduino Community within the open source ecosystem and to make our commitment to open source stronger than ever. This is really a new beginning for Arduino!”
“Of course, we are thrilled to resolve the issues that have taken place over the past couple of years, and the team is working together to continue to offer the best open hardware and software,” said Federico Musto, CEO & President of Arduino Srl. “We know how passionate our partners and developers are about Arduino, and the growth and loyalty has been astonishing. Arduino developers will continue to see amazing technical developments including NFC, BLE, voice controls, and more, to fuel the IoT growth and other innovations.”

Thursday, July 21, 2016

Controlling AC Loads with a MOSFET

In past articles I have shown how to control dc loads with a logic level MOSFET, but did you know you can control AC loads as well, just indirectly? The attached image shows the circuit diagram, and the MOSFET code and wiring is the same as our DC Projects. Can you figure out how this works?  For details, see

Use an IRL series n-channel MOSFET like the IRL520 or IRL540 that are designed to be driven at 5v.

Tuesday, July 5, 2016

Whole House Energy Monitor - Part 2

Testing the first batch of WHEM boards, I discovered a mistake in one of the traces. Out came the rotary tool, and I ground out two trace connections, and soldered in 2 jumpers. This will be corrected on the REV 2 boards. Two tools I would not be without are my WEN Rotary Tool and my Board Holder.

The parts call out is:

R1 - 100k Ohm
R2, R3, R4, R6, R7, R9, R10 - 10k Ohm
R5, R8 - 44.2 Ohm
C1, C2, C3 - 10uf 16v

I_Sense_1 & I_Sense_2 - SCT016 120a / 40ma (one for each leg of your breaker box)
V_Sense - 9vac transformer

Order boards, parts, and finished assembly at

R4 isolated and jumpered

Correct V_Sense Schematic - R4 (bottom 10k)

Parts Kit

Tuesday, June 14, 2016

Whole House Energy Monitor

Our board design for the whole house energy monitor just went to production, boards should be here in about 2 weeks (See update). We made this a through-hole design for ease of assembly (kit version) and modification. Complete kit consists of the circuit board, 2 current transducers, 1 drop down transformer, screw terminals, and a handful of resistors and capacitors. All that is needed is a Arduino and a Ethernet or WiFi board to transmit readings (amps and volts recorded, watts and watt hours are calculated) to our hosted (or your own) database so that the user can log in and see their daily, weekly, monthly and yearly consumption. We have discussed how to monitor whole house power and energy previously at, and sent out a couple of hand soldered perf board prototypes, but now have a professional solution which will be available in bareboard, kit, and finished versions. The data is stored and displayed on a hosted or optionally, a local server (Raspberry Pi). We have also discussed building your own web / database part of this solution at

Thanks to and Scott Quirk for making this project possible!

On the parts kit, let us know if you have a 5v or 3,3v controller. 
You supply the Arduino and ethernet shield.


Sunday, April 10, 2016

The Simple Way to Create a Raspberry Pi Boot SD Card

You probably have read instructions about burning images and special software needed to create the sd card to boot your Raspberry Pi, but none of that is needed. Grab a 8GB+ SD Card, and follow along with this simple, easy tutorial:

On your Windows, Mac, or Linux PC, go to and download the NOOBS Offline and network install zip file. It's about 1 GB in size, so this could take a bit. Go make a cup of coffee while you wait!

After downloading, extract the zip file to your new or freshly formatted (FAT32) sd card. Do not create a new folder.

Once finished, insert the sd card into your Raspberry Pi, connect power, HDMI video, (optional network cable) and keyboard/mouse and you are off and running. Just follow the Pi's onscreen install instructions.

Accessories we use and recommend are:

Logitech Wireless Keyboard / Mouse Combo 
Edimax Wifi USB
2.5 amp USB Power supply
16GB SD Card
HDMI Cable

Tuesday, March 29, 2016

The Best Dang Raspberry Pi Tutorial!

I've been a big fan of Simon Monk for quite a while. Whether it's his Arduino evil genius books, or his electronics "courses", It's always educational and fun to read. This time, Simon takes us on a updated journey through the Raspberry Pi. From explanation of  the hardware and software, through setup, to programming in Python, creating user interfaces, and reading and controlling electronics through the I/O pins, this book covers it all with an easy to understand helpful tone. Perfect for beginners, but not boring for those of us with prior experience.

Programming the Raspberry Pi, Second Edition: Getting Started with Python

As usual, all the code mentioned in the book is available for download at his website, and new projects continue to be posted on his blog. 

About the Author

Dr. Simon Monk has a bachelor’s degree in cybernetics and computer science and a Ph.D. in software engineering. He is now a full-time writer and has authored numerous books, including Programming Arduino, 30 Arduino Projects for the Evil Genius, Hacking Electronics, and Fritzing for Inventors. Dr. Monk also runs the website, which features his own products.

Sunday, March 6, 2016

Speaking Appliances for the Visually Impaired

We are working with an organization that provides adapters and converted equipment to announce status messages by speech instead of visually. We have speech enabled shop measuring equipment like calipers, micrometers and dial indicators, weather stations, and thermostats, and are working of speech enabled appliances, motion sensors, and other common gadgets. To help fund this endeavor, we have reduced the prices of all our ebooks at to $10 each.

To see a bit of what we are working on, see:

Friday, March 4, 2016

The Death of Electronics as a Hobby?

"The reports of my death are greatly exaggerated"

I tried to reorder some chips recently, that I have had no issue getting over the years. I'm told they are no longer manufactured. I contacted Maxim about the part, and received the following response:

We have very few through hole devices, and are actually moving away from through hole designs. So unfortunately, we do not have a through hole device that matches your requirements.

Industry is following the commercial customer, the money. Manufacturers use robotics to build boards, they order millions of a chip. Hobbyists use their hands, they order thousands of a chip. Does it pay to make a through hole version when most of your sales are smd?
This will continue the trend for companies like Sparkfun, Adafruit and ICBreakout to produce breakout boards so that those of us who like to experiment and build stuff aren't reduced to burning our fingers and destroying our eyesight trying to manipulate parts designed to be deployed by machines, but at a much higher cost than the chips alone, and reduced availability.

Monday, February 29, 2016

AC Current Monitoring, Current Transformers and Burden Resistors

In past articles we have covered monitoring DC current for solar and wind based applications.

Monitoring AC (grid or grid tie solar) is a bit trickier as voltage flows bidirectionally, and it's harder to insert a shunt inline. We use what is called a Current Transformer, or CT. It clips over your existing wires into your breaker box, so no disrupting the existing lines is necessary. In order to monitor AC current with a CT, you need to put a resistor across its output. This is called a burden resistor. To determine the correct resistance of this resistor, we need a few pieces of information.

As you can see in the picture, the maximum current rating, and the current output at that rating is displayed on the CT. Its rated for 120 amps, and outputs 40ma at that draw. If we divide the 120a by the .040 amp (40ma) output, we get 3000, which is the number of turns on the secondary.

Now, we need to know the Primary Peak Current (PPC), so we Multiply the RMS Current (120A) by the Square Root of 2 (1.414). This gives us a PPC of 169.68 Amps. We can calculate the Secondary Peak Current (SPC) by dividing the PPC by the number of turns (3000), so the SPC = .05656 amps.

Now, to determine the Ideal Burden Resistance. We need to know the AREF voltage of our microcontroller, which in the case of the Arduino UNO, is 5v. We divide the AREF by 2, and that by the SPC, so our calculation looks like this:

(5/2) / .05656 = 44.2 Ohms

Therefore, 44.2 Ohms (a standard 1% value) is the ideal resistor to put across the output of the CT to measure current. A complete measuring circuit and Arduino code to follow shortly.

Monday, February 22, 2016

Participate in our Smart Meter Trial

We are building a Arduino based smart meter, and are looking for participants to help fill the database with power usage data. All we ask is that you cover the basic costs of the meter system, and we will give you a web login that allows you to see your daily, weekly, monthly and yearly power usage. "Currently" the system requires a ethernet connection to your broadband router, but wifi is coming soon. The complete package comes with:

Arduino UNO
Ethernet shield
power sensor board
two snap on 120A current transducers
9vac wallwart
Proto Screw Shield

The current transducers clip over your main power leads into your power box and the small wall transformer measures voltage and powers the Arduino. The total cost is $120 + $14 S&H (US), and you get free power monitoring / data access on our upcoming website and with Apple and Android Apps. Email Steve Spence if you are interested in participating or order below!

Off Grid versions are also available.

Thursday, February 18, 2016

Arduino Mitutoyo Sorter

by Tom Lemos, LFI Medical

"We were tasked to come up with a device, an automatic sorter, that would allow us to determine whether the parts we were laser welding were either a "GO" or or a "NO GO" based on our customers requirements. We wanted to come up with something in-house that would be effective but affordable and decided to try using an Arduino, something which nobody within the company had any experience with. We soon learned that there was a little more to this than we expected, and that's where Steve came in. His experience with the Mitutoyo product line, his ability to write code, his custom made circuit boards and his willingness to work with with us were all instrumental in making the project a success.

In the beginning of the attached video you will see the R&D version of what we came up with in operation. There is the dual interface board Steve made which allows us to gather data from the two Mitutoyo indicator gauges and send it to the Arduino, along with a de-bounce cycle start button board for reliable initiating of the cycle, also made by Steve. There is also the Arduino itself, along with a 4 output relay board for the pneumatics and a breadboard back there.

The video shifts to the front where a "GO" part is being manually loaded (green top) and the cycle start initiated. The part is captured, the stepper drive starts rotating the part and the data from the Mitutoyo gauges is generated and sent to the Arduino, all of which takes about 20 seconds or so. In this case the part is good so the pneumatic diverter at the bottom does not move and the part drops through the hole on the left. When the process is repeated with a "NO GO" part (red top) the same measuring takes place but this time the data is outside of what is acceptable so the pneumatic diverter sends the part into the hole on the right for further evaluation. Pretty neat!

Again, I cannot emphasize enough how helpful, and patient, Steve was with this whole project. He is an excellent source for code and hardware and seems more than willing to help make your project a success."

Tom Lemos
LFI Maintenance Manager

Thursday, February 4, 2016

Arduino and Raspberry Pi Educational Resources

I've been a fan of Packt Publishing technical books for a long time. I've purchased quite a few volumes for my Arduino and Raspberry Pi library, and even had the honor of being a technical editor. Now you can get a years access to their complete library of titles:
With PacktLib subscription service, you have access to every single book in Packt’s huge library of over 3,000 strong eBooks and videos, especially the latest releases that are available as soon as they’re published. All you have to do is set up a subscription here to get access to the whole service for a full year.
I value my subscription and the great breadth of research available to me on my computer and Kindle. It's hard to put a price on such a resource, and fortunately, Packt put a affordable one on this.

I'm building Chapter 4. Arduino Security Camera with Motion Detection from "Internet of Things with Arduino Blueprints"

"Security is a concern for everyone. If you want to capture and record any activity within your home or office for security purposes, thousands of security camera models are available to fulfill the task. You can, however, make your own security camera, complete with Internet feedback and motion detection, and you can also access the camera images from your mobile's browser from anywhere in the world."

How to use TTL (Through The Lens) Serial Camera directly with NTSC video screen.
How to connect TTL Serial Camera to Arduino and Ethernet Shield.
How to capture images with TTL Serial Camera.
How to create Flickr and Temboo accounts and configure with Arduino Ethernet Shield.
How to upload images to the Flickr using the Temboo cloud service.
How to capture images with built-in motion sensor and upload them to the Flickr.

Wednesday, January 27, 2016

Arduino: PLC or PAC

The traditional Programmable Logic Controller (PLC) is used in process controls and Programmed in Ladder Logic. A more recent evolutionary step is the Programmable Automation Controller (PAC), which is typically programmed in C/C++, and has analog, digital, and communications functions built in. This is the arena where the Arduino (and even a Raspberry Pi) shines. No longer do process controls have to be expensive, proprietary, and mysterious. It's much simpler to control a pump or solenoid with a Arduino, by reading sensors (digital or analog) and writing short pieces of decision code. Data can also be sent by way of ethernet or wifi to a central database. There are even DIN Rail Mounts for mounting your Arduino and Screw shield.

Anyone can build industrial process controls, for very little expense, with very short development times.

Steve Spence builds Arduino based industrial process controls in a manufacturing / factory setting for his employer.

Additional resources:

Saturday, January 2, 2016

Using a 4x4 Keypad

Part 1 - I was working on a project for someone who needed a keypad for password entry. I couldn't find my 3x4 keypad, but found a 4x4 keypad in one of my parts boxes. I modified the example sketch that comes with the excellent keypad library to work with this particular keypad. I couldn't find a set of extended headers to directly connect the keypad to the Arduino, so I used a small protoboard.