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Need a “little” help with your next electronics project? Get it up and running with our sub-micro plastic planetary gearmotors! Measuring a minuscule 6 mm in diameter and weighing just over a gram, these gearmotors are even smaller (and much lighter) than our popular micro metal gearmotors.
|26:1 sub-micro plastic planetary gearmotor next to a micro metal gearmotor and a LEGO Minifigure for size reference.|
While there are no mounting holes, their cylindrical bodies makes them perfect for snapping into 1/4″ (6 mm) fuse clips, and their small scale makes it easy to affix them with tape or glue. We are also now carrying tiny 14 × 4.5 mm wheels, which are compatible with the sub-micro plastic gearmotor output shafts.
But, Jon, what can I do with such a tiny, adorable motor?
I’m glad you asked! The way I see it, you really only have two options:
- Spin something really tiny and adorable.
- Make something tiny and adorable like this line follower made by Pololu engineer Kevin (blog post coming soon!):
I’m just kidding; there are definitely plenty of interesting things that can be made with these motors. We can’t wait to see what you use these motors for!
We are now carrying metal servo horns that work with Power HD’s ultra-high-torque HD-1235MG giant servos, which can deliver a whopping 560 oz-in (40 kg-cm) at 7.4 V. If you want to get the most power out of your HD-1235MG, I recommend substituting one of these anodized aluminum horns for the included plastic horns.
We are now carrying four exciting new sensors from Interlink Electronics:
- 0.25″-diameter circle, short tail force-sensing resistor (FSR)
- 0.6″-diameter circle, short tail FSR
- 1.4″ × 0.4″ force-sensing linear potentiometer (FSLP) strip
- 4.0″ × 0.4″ customizable-length FSLP strip
The two force-sensing resistors (or FSRs, for short) are short-tail versions of the small, circular FSRs we already carry, which allows them to be integrated into applications with tighter space constraints. These sensors act just like variable resistors that depend on the applied pressure, so you can put them into a simple voltage divider circuit and measure the force on them with a single analog-to-digital (ADC) microcontroller input.
|0.6″-diameter short-tail force sensing resistor (FSR) next to a 0.6″-diameter FSR with a standard tail.|
The two force-sensing linear potentiometers (or FSLPs) take the force-measuring functionality of FSRs and add in the ability to detect the location of the force, all while being an entirely passive component that is incredibly easy to use.
|The two force-sensing linear potentiometers (FSLPs).|
These FSLPs are exciting because they enable fun new touch interfaces, not only for you to interact with your project but for your project to interact with the world. We decided to make a quick demo for the Las Vegas Mini Maker Faire 2014 to show just how easy it was to do something cool with this sensor. The video at the top of this blog post shows the demo in action.
In the demo, a 4.0″×0.4″ FSLP is used with an Arduino Uno R3 to meassure the position and pressure of the user’s finger. (For applications where space is tight, smaller modules like our Arduino-compatible A-Star Micro can be directly substituted for the Uno.) Using the strip requires four connections to a microcontroller and one additional resistor. Two of the required connections must be analog inputs. Four connections for one sensor might seem like a lot to deal with, but step-by-step procedures in section 5 of the sensor’s integration guide (513k pdf) make it easy to get the sensor working, and the Arduino code used in this demo is available on github to help get you started. A diagram of the connections made between the sensor, Arduino, and LED strip in this demo are shown below.
The connections shown in the diagram also work with the shorter 1.4″×0.4″ FSLP (referred to as “standard FSLP” in the integration guide), though the pin numbers that correspond to each of the sensors outputs (SL, D1, and D2) are different for the two sizes of FSLP. The pin numbers for each FSLP can be seen in Figure 9 of the FSLP Integration Guide. In the guide the 4.0″×0.4″ FSLP is referred to as a “10 cm FSLP”.
Once the Arduino reads the position and pressure data from the sensor, it sends signals to a WS2812B addressable LED strip that control the number of LEDs that turn on and their color. The further along the strip your finger moves the greater the number of LEDs that light up, and the more pressure you apply the more the color of all the LEDs changes from blue to red.
To make the demo easy to transport and able to be left on all day, a 9V wall adapter was used to power the Arduino and 5V step-down regulator. The power connections from the regulator’s 5V output to the power input of the LED strip were also simplified by using a DC barrel jack to terminal block adapter and a DC barrel plug to terminal block adapter. The structure of the demo was laser cut from 1/8″ clear acrylic, and aluminum standoffs were used as spacers.
If you guys do something cool with our force-sensing linear potentiometers or resistors, we’d love to hear about it!
Level shifting is a common issue when interfacing multiple microcontrollers or other digital logic devices. For example, you cannot directly connect an Arduino running at 5 V to the Wixel, which runs at 3.3 V. Our Wixel Shield for Arduino contains several level-shifting circuits to help you do this.
In some cases, such as connecting a digital sensor output to your microcontroller, a simple voltage divider or transistor inverter might be good enough. However, in many cases a better solution is necessary. I²C, for example, is a common protocol that makes use of a bidirectional communication line. Luckily, a relatively simple circuit consisting of a MOSFET and two pull-up resistors can be used for general-purpose bidirectional level shifting:
|Schematic of a single bidirectional logical level shifter.|
We have used this level shifter circuit on many of our breakout boards operating at a lower voltage, such as the MinIMU-9. It works like this:
- When Lx, the lower-voltage input, is driven low, the MOSFET turns on and the zero passes through to Hx.
- When Hx, the higher-voltage input, is driven low, Lx is also driven low through the MOSFET’s body diode, at which point the MOSFET turns on.
- In all other cases, both Lx and Hx are pulled high to their respective logic supply voltages.
The circuit works for any pair of voltages (within the limitations of the MOSFET) and can be used with most common bidirectional and unidirectional digital interfaces, including I²C, SPI, and asynchronous TTL serial. You can read more about it in NXP’s application note on I²C bus level-shifting techniques.
Today we released a logic level shifter board featuring four of these bidirectional channels:
Our board can convert signals as low as 1.5 V to as high as 18 V and vice versa, so you can use it for almost any logic-level signals that you might encounter in your project. It is also, as far as we know, the smallest bidirectional logic level conversion board out there:
Note the use of a more internationally-appropriate size reference than our traditional U.S. quarter. After we put together this image, nobody believed that the board was actually that small, but we verified it several different ways to make sure.
Anyway, with this board’s small size, low cost, and versatility, we think it is something that everyone should have in their toolbox. For more information or to order, see the product page.
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Looking for a way to pump up your next project? Let the Muscle Sensor v3 from Advancer Technologies do the heavy lifting!
This small, easy-to-use, 1″ × 1″ board measures muscle activation via electric potential; this is referred to as electromyography (EMG). The sensor measures, filters, rectifies, and amplifies the electrical activity of a muscle; as the muscle flexes, the output voltage increases, resulting in a simple analog signal that can easily be read by any microcontroller with an analog-to-digital converter (ADC), such as our A-Star or an Arduino.
|Muscle Sensor v3 with included hardware.|
The engineers here were pretty excited to play with these when we got our first samples, as many of us hadn’t used anything like it before. While thinking of various ways to test the sensor, a few of us remembered this ridiculously awesome video of Terry Crews making music with his muscles. (Gets me every time! #MuscleEnvy.) Without getting ahead of ourselves, we decided to try something much quicker and more straightforward with some of our electronics.
In the demonstration video at the beginning of this post, you can see the muscle sensor in action as it measures the muscle activity of my bicep. The demo uses the muscle sensor with a Maestro servo controller to update the position of a hobby RC servo based on how hard I flex. The setup was very simple; the analog output signal from the muscle sensor is connected directly to channel 0 on the Maestro, and the two boards share a common ground. The muscle sensor is powered by two 1S LiPo batteries and the Maestro and servo (connected to channel 1) are powered from a separate 6 V battery pack.
|Here I am modeling with electrodes on my bicep for the Muscle Sensor v3.|
The Maestro script we used is very similar to the “Using an analog input to control servos” example script provided in the Maestro user’s guide with a couple of modifications. We changed the scaling of the input channel (since our signal was from 0 V to 3.7 V) as well as the channel numbers to match our setup. The whole script is only a few lines long:
# Sets servo 1 to a position based on the analog input of the Muscle Sensor v3. begin 0 get_position # get the value of the muscle sensor's signal connected to channel 0 6 times 4000 plus # scale it to roughly 4000-8092 (approximately 1-2 ms) 1 servo # set servo 1 accordingly repeat
We can’t wait to see all of the amazing things you come up with when you engage your brain (and your muscles) with this sensor!
Inevitably, if you work with electronics long enough, you will encounter a wire that is too long, too insulated, or too connected (to the wrong thing), and while you might be able to MacGyver your way out of the situation with a pair of scissors or a suitably hardy set of teeth, nothing beats a good wire stripper. With that in mind, we set off in search of some good, basic wire strippers that would get the job done well without breaking the bank. Our favorites were a set of multi-purpose wire strippers and cutters that feature comfortably curved and cushioned grips and a nose that can be used as pliers. One version works with 10 to 20 AWG wires and another works with 20 to 30 AWG wires. (The stripping holes are labeled with the gauge of solid-core wire for which they are intended; for stranded wire, use the next larger hole.)
We have expanded our selection of miniature tank tracks to include a variety of colors. The new tracks are identical in function to the black miniature track links, but now come in blue, red, and yellow. Track links of different colors can be combined to create fun and interesting patterns to give your robot some added character.
These miniature track links work great for small indoor robots, especially on carpet, and they are compatible with a variety of injection-molded sprocket sets such as:
- 8T Hex for use with Tamiya gearboxes
- 8T Futaba for use with continuous rotation servos with Futaba-compatible servo splines
- 8T GM for use with Solarbotics GM gearmotors and Pololu plastic gearmotors
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