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New Product: Rigid RGB LED Strips

rigid_rgbled_threeWe picked up these nice Rigid RGBLED Strips from one of our suppliers for a good price. They contain 30 5050 RGB LEDs which seem to be standard super-bright LEDs, they are 12mm wide and 500mm long with headers every 50mm where they can be cut and soldered. The have nice polarized connectors and six inches of cable on the ends which makes mating them in series simple and quick and easy. Priced low enough that you could afford to take off the LEDs and use them on other projects (.20 ea). The resistors are sized to lend nice balanced white light that is not too cold in color, when powered from 12 volts. The 12V trace which looks to be about 60mils wide is mirrored front and  back for extra current-carrying capability.

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By Britton on October 6, 2015.

Maxbotix Ultrasonic Rangefinder MB1013 (1mm Resolution) Proveout

A month or so ago we decided to carry the Maxbotix’s line of ultrasonic rangefinders (the MB1010, MB1013, and the MB1200 are the models we have currently stocked).  The MB1013 in particular caught our eye in its claim to have a resolution of 1mm, so we decided to put it to the test. We lashed together a test rig with two panels (of plywood) that are raised and lowered by three drive shafts of 1/32″ threaded rod (pictured below).




The board has two holes in the opposite corners that make mounting to a surface a no-brainer. We quickly proved out the analog output using a 5v power supply and a multimeter, but we wanted the most precise measurement. Opting for the serial (digital) output  reading with an Arduino- both methods are covered in the Maxbotix tutorial. For ease of documentation, we hooked up the Arduino to an LCD driven by our LCD117 board, for an easy three wire interface to the LED. This was just handy way to get feedback without a laptop or desktop. Actually the USB cable in the picture below snakes about 10 ft to the nearest desktop in our shop.


Our threaded rod was 32 threads per inch, which is equivalent to 24.4 mm, so one thread represents 32 threads per inch / 25.4 mm per in. or 1.25984 threads per millimeter. This allowed us to index the jig 1.25 turns per unit and not have a lot of error, with an error of .246 threads per 25 turns. In any case we indexed all the way through one inch,

Our results showed that it does indeed have a 1mm resolution, meaning that 1 1/4 turns did actually correspond with a Maxbotix output of 1mm! Our algorithm kept the readings consistent with the range up until around 620mm – where the sensor’s output started to report smaller values than the measured distance, ending up 8-10mm ahead of where it was supposed to be at 582 mm. Maxbotix cuts off the serial output of the sensor at 300mm (11.8″) so one could speculate that the error in the electronics started to be a factor in the measurement, which lead to Maxbotix to cut off the specification at 300mm.



Check out the raw data here.

The max range and cone shapes vary from the sensors we have available. They could be used for things like a parking sensor (found in most modern cars), self-navigating robots, or a suit that helps you navigate blind. Maxbotix has done a great job  of taking ultrasonic measuring technology and pushing itas far as they can in accuracy, range and sensing properties (sensing cones) in these very low-cost sensors. Here’s a line up of the models we carry at Modern Device.

MB1010 LV-MaxSonar®-EZ1 – Least Expensive, good starter ($27.97)

MB1013 HRLV-MaxSonar®-EZ1 – Highest Resolution (1mm)

MB1200 XL-MaxSonar®-EZ0 – Longest Range (300in)


We got in contact with the good people at Maxbotix and showed them our research. They were pleased to see us exhibiting their equipment, and gave us some feedback on our setup…

First, I reviewed your test setup and thought you did a pretty good job. As such there is a variable that can make a big difference in your testing results. This is the temperature compensation and the location of measurement. Going though a vertical column of air is known to typically have temperature variation from the top vs the bottom. This change in temperature can affect the temperature compensation of the sensor and lead to some inaccuracies. For best accuracy, it is recommended to use a MaxTemp mounted half way between the target and sensor so that you have the most accurate temperature reading. Even one or two degrees c will have an effect on the reported range. 

You can view more on the MaxTemp at this link

By Britton on January 28, 2015.

New Product – ExtraCore MD – Alarmingly tiny Arduino Clone!

Dustin Andrews created the first ExtraCore Arduino which is the size of a postage stamp. We sold the first batch we had, and by that time, the original was extinct as Dustin had moved on to another job and didn’t want to make more. We decided to respin the board with a few improvements and a smaller chip. The result of our efforts is in the shop  here .

The ExtraCoreMD, as we’re calling it, is a minuscule form factor Arduino clone, ideal for applications where space and weight need to be kept to a minimum- aircraft, robotics, fashion, wearables. The size of the board is .92″ x .825″ (21mm x 23mm), and it is manufactured on 1.3mm PCB for a sleek height profile of only .09″ (2.2mm). The board is small enough to conceal in jewelry, or DIY musical greeting cards, or wearable tech, if you’re crafty.

Programming is through our USB BUB or any standard FTDI cable, unlike the first ExtraCore. We also made one non-fatal mistake in the boards, although we are revising them immediately. The labels on the VCC and Vin are just swapped.

We cooked up a quick example app, just to prove out the board, using 18 pins (all the I/O except RX & TX) LED’s with a basic loop. Keep posted for more experiments using this board.


There are more details on the product page:

We’re giving away ten of the boards, with orders over ten dollars. Use coupon code EXTRACOREMD.

By Britton on January 23, 2015.

New Product Bundle: Jeelabs Mini Starter Kit!


We are introducing a starter kit for JeeLab’s JeeLink and JeeNode SMD!

This Jeelabs Mini Starter Kit kit comes with everything you need to start working with wireless communication. We have also included a USB BUB II to interface with the JeeNode SMD. All products are surface mount and require little assembly to attach headers. We can also solder all headers on both the JeeNode SMD and the BUB II for an additional charge.

Save 25% off both the Jeenode SMD and the JeeLink, and 28% off the USB BUB II when you purchase them bundled together!

If you for some reason decide to get to different frequencies please let us know in the customer comments upon checkout. The kit will not work together if you purchase two different frequency modules.

By Britton on December 29, 2014.

Free Shipping Every Weekend!

We offer Free USPS First Class Domestic shipping every weekend for orders over $10 to help you save a few bucks here or there. We tend to start the weekend early, so Free Shipping gets activated around 3pm EST Friday, and deactivated at 10am Monday. If for some reason the option is not available, please feel free to contact us and we will fix that!

Despite offering this for quite some time, I have noticed that not everyone takes advantage of this offer. When checking out, make sure you select the option “Free Shipping on Weekends, Domestic US only.” Please note that orders that are over 13oz in weight are not eligible for First Class Mail, and you will have to use another option.

By Britton on December 5, 2014.

A Stereo Audio Amplifier





The Modern Device Stereo Amplifier breakout board is a minimal Stereo Amp designed to amplify small projects, such as amplifying the Fluxamasynth Shield, or an Adafruit Wave Shield for personal use in fairly quiet spaces. It is probably not loud enough for a good dorm-room dance party. It is also great for increasing the volume level of your Arduino or other micro-controller when used for musical projects.

A few words about the demo. We are using the Arduino just for a convenient source of 5 volts to power the amp. The output is directed to two  of our 8 ohm loud-speakers inserted into coffee cups for better amplification. We specifically bought a size that could be used with a coffee cup as a speaker enclosure. This was a trick I didn’t originate but picked up from one of my resourceful students.  For this project, we found that cutting a hole in the back of the cup produces a warmer sound, as opposed to leaving it covered. The left and right potentiometers control the volume of the left and right channels as you would expect.

As in the mono version of this amplifier, we have used real analog volume controls to make adjustment of volume easy. While it can be useful to have software control over output volume, it can also be useful in many situations, to have physical control over output volume. The example I sited in my post on the mono amp is still the first and best one that comes to mind. You have a piece installed in an art gallery and you want it to be heard during the opening of the exhibit. Typically art galleries are very crowded during openings, people have been drinking and the volume is loud. Afterwards there are typically between 8 and 0 people in the gallery, with much lower sound levels. Being able to physically tweak the volume is an easy way to set appropriate volume is very useful. Many other situations exist, even with digital sound, where a simple potentiometer is more effective than two buttons with some kind of “up-down” digital interface.

The Modern Device Stereo audio amplifier breakout board uses the LM4992, one of National Semiconductor’s “Boomer” amps. It uses what in the industry is referred to as a “bridge-tied load”. This is an efficient system that increases the total amount of power available to the speaker with low-voltage systems. It also eliminates the need for an output capacitor, (like in the LM386) which tends to be bulky and can limit the low-end response. It has a shutdown pin to put the chip to sleep, just in case you’re trying to build a super low-power microcontroller application that spends most of its time sleeping.

All this in a really small package.  Here are some specs with a 1khz signal.

Power Out VCC THD & noise Load (speaker ohms)
1W 5 volts  .1% 8 Ω
.4W  3.3 volts .1% 8 Ω

This is not quite CD quality sound, since this chip was designed for cell phones, but then neither are most of your other electronic appliances (such as phones and mp3 players) these days. Pop music still seems to be doing fine.

Ships with a two terminal blocks,  a 4 pin male header, and two 200K pot which all not soldered onto the board. All other parts are assembled and tested and ready to go.  It’s in the shop here.

By Britton on July 28, 2014.