Pololu Blog (Page 34)
Welcome to the Pololu Blog, where we provide updates about what we and our customers are doing and thinking about. This blog used to be Pololu president Jan Malášek’s Engage Your Brain blog; you can view just those posts here.
If you’re looking for an inexpensive motor driver that works with higher voltages, but our DRV8801 carrier’s single channel isn’t enough, we now offer another option: a carrier board featuring Allegro’s A4990 dual motor driver.
The A4990 can deliver a continuous current of up to 0.7 A per channel at voltages from 6 to 32 V, making it a good choice for small, low-current motors that run on relatively high voltages. Onboard sense resistors enable the A4990 to actively limit the peak motor current to about 0.9 A per channel, and the carrier board adds a reverse-voltage protection circuit in addition to the robust IC’s built-in protection against under-voltage, over-voltage, over-temperature, and short circuits.
For more information, see the A4990 carrier product page.
This week we started selling new addressable RGB LED strips. These LED strips are a great way to add some color to a project, and I would like to show a little bit about how they work. Here is a close up showing one segment of a new LED strip:
Close up of one segment of a WS2812B-based LED strip, with the red, green, and blue LEDs on at their dimmest setting.
At first glance, it is easy to see the RGB LED and a capacitor, but where are all the other components, such as the LED driver? Well, let’s look more closely at the LED:
Close up of a WS2812B, with the red, green, and blue LEDs on at their dimmest setting.
The LED actually has a driver built into it, which is the large brown rectangle in the picture. This driver receives high-speed color data, storing the first 24 bits it sees and passing the rest of the bits down the strip to the next LED. The driver is connected with tiny wires to the red, green, and blue LEDs. For the photos above, we turned each of the LEDs on at its dimmest setting so you can see their colors. This integrated circuit (IC) consisting of an RGB LED and a driver is called the WS2812B.
Since the WS2812B integrates an LED and a driver into the same package, we are able to offer higher density strips than before. We offer these WS2812B LED strips that have 60 LEDs per meter:
We also offer these WS2812B LED strips that have 30 LEDs per meter:
All of our example code has been updated to fully support the new strips. We provide example code for the Arduino, AVR, and mbed microcontroller platforms. More information about the LED strips and how to use them can be found on the LED strip product page.
Controlling an addressable RGB LED strip with an Arduino and powering it from a 5V wall power adapter.
Are you having trouble mounting things to 1/4″ motor shafts? These new versions of our universal mounting hubs fit most 1/4″ shafts, including round and “D” shafts. Similar to our existing universal mounting hubs for 6 mm shafts, these hubs are sold in packs of two and come with two set screws each (4 total) and the appropriate Allen wrench. These new hubs are compatible with our NEMA 23 stepper motors and come in two different versions: the Universal Aluminum Mounting Hub for 1/4″ shaft, with #4-40 mounting holes or the Universal Aluminum Mounting Hub for 1/4″ shaft, with M3 mounting holes.
Get a FREE copy of Elektor magazine’s December issue with your order while supplies last. To get your free issue, enter the coupon code ELEKTOR1213 into your shopping cart. The magazine will add 5 ounces to the package weight when calculating your shipping options.
For other issues and more information, see our Free Elektor Magazine Offers page. All issues are now available for shipping worldwide!
As you might have noticed from some of our recent blog announcements, we are steadily working on expanding our selection of hobby servos, and the latest example is Power HD’s new giant-scale (also called 1/4-scale) 1235MG servo. When compared to the popular, standard-size high-torque 1501MG servo, it is easy to see why this is called a “giant” servo:
What you get for the increased size is increased power — a huge 560 oz-in (40 kg-cm) of torque at 7.4 V or 490 oz-in (35 kg-cm) at 6 V. Previously, if you needed more torque than our high-performance standard-size servos could deliver, our only options were the Torxis monster servos; now, the 1235MG servo helps fill that power gap.
For more information, see the 1235MG servo product page.
We have included this servo in our Black Friday sale (along with the rest of our Power HD servos) for 25% off, but the sale ends tonight at midnight (PST), so you need to hurry if you want to get it at the sale price!
While our laser cutting machines can only cut two dimensional parts, there are easy ways to make three-dimensional designs out of flat, laser-cut parts. A simple way to achieve this is to create slots in the vector design to allow the two parts to slide together perpendicular to one another. Some may remember this technique from childhood arts and crafts; this easy tweak allows parts to be easily assembled and disassembled.
These Chandeliers by Nicole Ketchum were created using our 3 mm acrylic with a slot width of 1/8″. You can adjust the width of the slot depending on how snug you’d like them to fit. Since Nicole’s chandeliers are meant to be hung out of reach, a really snug fit wasn’t needed. With the holidays right around the corner, these could spruce up any room of your home!
For more details on using slots to fit acrylic parts together, be sure to check out Nicole’s project in our Custom Laser Cutting Gallery. More details about our custom laser cutting service can be found here.
Pololu shipping department on Black Friday (November 29) 2013.
Our Black Friday sale is in full swing and it is a little crazy around here. If not for the lack of snow and elves, one might be excused for mistaking our manufacturing and shipping departments for Santa’s high-tech workshop, with motor drivers fresh from the oven and that new-Zumo smell wafting through the air. Thanks to their tireless efforts, our stock levels are so far holding strong, and orders are making it out at a record pace. If you have already placed an order, thank you! If you are still trying to decide if you want to take advantage of our amazing deals, don’t wait too long—the sale ends Monday night.
In related Black Friday news, Pololu distributor Banana Robotics is having a Black Friday – Cyber Monday sale with some great deals!
We are now carrying three high-performance servos from Power HD that offer an excellent combination of strength and speed for their size.
Power HD Low-Profile Digital Servo 1207TG – This servo is very fast and strong, despite being much shorter than a standard-size servo, making it great for applications with tight space constraints.
Power HD Digital Servo 8312TG – Much stronger than the 1207TG while nearly as fast, this servo is great for applications that require both high speed and high torque. All of the gears are made of titanium-shielded aluminum.
Power HD High-Torque, High-Voltage Digital Servo 1218TH – With a whopping 290 oz*in (21 kg*cm) of torque, this is our strongest standard-size servo, and unlike most hobby servos, it has an operating voltage range of 6 V to 7.4 V. Like the 8312TG, this servo has gears made of titanium-shielded aluminum.
All three of these servos feature coreless motors, all-metal gears, and digital control electronics, and all of them support pulse frequencies up to 333 Hz. For our full selection of Power HD servos (which are on sale right now for Black Friday for 25% off!), see our servo category.
Our Black Friday sale is back, and this one is our biggest yet. We are discounting hundreds of products by 30% to 60% and offering an additional 11% to 15% off orders over $100. The sale coupons and price changes become active in just over 6 hours. We hope these deals give all you robotics and electronics enthusiasts out there a happy start to the holiday season! For coupon codes and sale information see our Black Friday Sale 2013 page.