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New product: STSPIN820 Stepper Motor Driver Carrier with 1/256 microstepping

Posted by Jan on 27 November 2018
Tags: new products

We have yet another new stepper motor driver carrier in our popular 16-pin, 0.6″ × 0.8″ form factor, this time for STMicro’s STSPIN820, which offers 1/256 step microstepping! ST actually has their own similar evaluation board, the EVALSP820-XS, but the STSPIN820 chip has a non-inverted Enable input, which is inverted compared to most other stepper motor driver ICs out there, and they expose the pin that way on their version of the board. We have thoughtfully added a transistor-based inverter so that our board is more likely to work as a drop-in replacement (or upgrade!) for the stepper driver boards you already have. In our tests, the Pololu carrier supported a substantially higher maximum current than the ST eval board (around 900 mA compared to 720 mA, probably due to our board having four layers vs. two layers for the ST eval board), and as of this writing (27 November 2018), our board is also priced lower.

You can see the full schematic for all the details (this schematic is also available as a downloadable pdf (109k pdf)):

Schematic diagram of the STSPIN820 Stepper Motor Driver Carrier.

With our release earlier in November of compact carriers for Toshiba’s TB67S249FTG and TB67S279FTG stepper motor drivers, we now offer ten different stepper motor driver modules in this compact size:


A4988
(original)

A4988,
Black Ed.

DRV8825

DRV8834

DRV8880

MP6500,
Pot. CC

MP6500,
Digital CC

TB67S279­FTG

TB67S249­FTG

STSPIN­820
Driver chip: A4988 DRV8825 DRV8834 DRV8880 MP6500 TB67S279­FTG TB67S249­FTG STSPIN­820
Min operating voltage: 8 V 8.2 V 2.5 V 6.5 V 4.5 V 10 V 10 V 7 V
Max operating voltage: 35 V 45 V 10.8 V 45 V 35 V 47 V 47 V 45 V
Max continuous current per phase:(1) 1 A 1.2 A 1.5 A 1.5 A 1 A 1.5 A 1.1 A 1.6 A 0.9 A
Peak current per phase:(2) 2 A 2.2 A 2 A 1.6 A 2.5 A 2 A 2 A 4.5 A 1.5 A
Microstepping down to: 1/16 1/32 1/32 1/16 1/8 1/32 1/32 1/256
Board layer count: 2 4 4 4 4 4 4 4 4
Special features: high current low-voltage
operation,
high current
AutoTune,
digital current
reduction
high current digital current
control,
high current
Auto Gain Control,
ADMD,
high max voltage
Auto Gain Control,
ADMD,
high max voltage,
high current
128 and 256
microsteps
1-piece price: $5.95 $7.49 $8.95 $5.95 $6.95 $5.95 $5.95 $7.75 $9.95 $7.75
1 On Pololu carrier board, at room temperature, and without additional cooling.
2 Maximum theoretical current based on components on the board (additional cooling required).

As with all of our new products this year, we are offering an introductory special. The first 100 customers that use coupon code STSPIN820INTRO can get up to five units at just $5 each.

New products: TB67S249FTG and TB67S279FTG Stepper Motor Driver Compact Carriers

Posted by Jan on 17 November 2018
Tags: new products

Earlier this week, we released new compact carriers for Toshiba’s great stepper motor drivers, the TB67S249FTG and TB67S279FTG. We released larger carrier boards for those two chips in the summer, and those are still the version to get if you want to test all the features that those ICs offer. The new compact carriers are in our popular 16-pin, 0.6″ × 0.8″ form factor (which I originally designed for the Allegro A4983 back in 2009 when I was still routing most of our circuit boards), making it easy to use the new drivers on RAMPS-type 3D printer controllers that have the compatible sockets.

These Toshiba chips are massive, and you can see how much more space they take up on that common PCB size when compared to the original board (populated with the Allegro A4988 that replaced the A4983):

TB67S249FTG Stepper Motor Driver Compact Carrier (top view).

A4988 stepper motor driver carrier, top view (shown with original green 50 mΩ current sense resistors).

In addition to fitting the larger chip onto the same board space, we had to add some external inverters to make the enable and reset lines behave the same way as on the original modules (this schematic is also available as a downloadable pdf (141k pdf)).

Schematic diagram of the TB67S249FTG/TB67S279FTG Stepper Motor Driver Compact Carrier.

We also had to hardwire many of the options that the TB67Sx49FTG chips offer. In particular, we set the Active Gain Control (AGC) lower current limit to 60%. This innovative feature on the Toshiba stepper drivers allows the current through the stepper motor to be reduced based on what the motor actually needs, which allows for reduced unnecessary heat generation in the motor and higher peak power when you actually need it. I have heard (from Toshiba’s competitors, who also acknowledged that Toshiba is one of the few big semiconductor companies bringing real innovation to stepper motor drivers) of the AGC feature not working in some applications, but when it works, it’s quite amazing. We tried out the Toshiba TB67S249FTG drivers on a Tevo Tornado 3D printer that originally had Allegro A4988 drivers on an MKS GEN control board, and we could run at higher current and with 1/32 microstepping instead of the A4988’s 1/16 microstepping, which also gave a noticeable improvement in print quality.

The TB67S249FTG is now our highest-power option, and in addition to delivering a little bit more power than our previous leader, the TI DRV8825, the Toshiba driver seems to provide better current control with the relatively low inductance, low resistance coils often used on these low-end 3D printers. If you do not need that maximum current aspect, you can get all the other special features with the lower-power, lower-cost TB67S279FTG.

As with all of our new products this year, we are offering an introductory special. For these two new modules, we are offering 40% off for up to five units (per version!) to the first 100 customers that use coupon code TB67SCOMPACT. This means you can try out the top-of-the-line TB67S249FTG for less than $6.

New G2 Simple Motor Controllers

Posted by Jan on 15 November 2018
Tags: new products

Last week, we released updated (G2) versions of our Simple Motor Controllers. We released our original Simple Motor Controllers just over eight years ago as our most economical basic motor controllers for brushed DC motors using up to a few hundred watts. The “simple” in the name came from our trying to have fun with all the requests we had from our customers, many of whom wanted “just” this one feature. Of course, everyone wants a different feature in their minimal motor controller, so the Simple Motor Controllers actually have quite a few options, but we make it easy to set up with configuration over USB.

Status tab in the Pololu Simple Motor Control Center G2.

Input settings tab in the Pololu Simple Motor Control Center G2.

Pololu Dual G2 High-Power Motor Driver 24v18 Shield for Arduino.

Over the last few years, we have been updating our higher-power motor drivers (H-bridges with external MOSFETs) to use newer MOSFETs and MOSFET drivers, and we refer to them as our G2 high-power motor drivers. These drivers are available as small, single-channel boards, as well as dual drivers in Arduino shield and Raspberry Pi HAT form factors. Earlier this year, we brought the improved motor drivers to our Jrk G2 Motor Controllers with Feedback for those wanting to make their own closed-loop servo systems.

Now, the G2 motor driver technology is available on our Simple Motor Controllers as well. For the most part, this is not as big of a change as with the other G2 motor control products, but we did add a few nice features while maximizing backward compatibility. Key improvements over the originals include reverse voltage protection, configurable hardware current limiting, and the addition of an I²C interface for yet another control option—the others being USB, analog voltage, hobby RC servo interface, and asynchronous serial (UART). Additionally, the highest-power units (the SMC G2 18v25 and 24v19) use a four-layer board with double-sided assembly, which lets them be much smaller than their original SMC 18v25 and 24v23 counterparts:

Side-by-side comparison of the original SMC 18v25 and the newer SMC G2 18v25.

The lower-power units have the exact same size and generally have the same connector locations as the original Simple Motor Controllers:

Side-by-side comparison of the original SMC 18v15 and the newer SMC G2 18v15.

The most notable difference from a form factor and connection standpoint is the change from the USB mini-B connector on the older motor controllers to the micro-B connector on the G2 models. The following table shows the main specifications of all of the old and new Simple Motor Controllers:

Original versions, not recommended for new designs
(included for comparison purposes)
G2 versions,
released November 2018

SMC
18v7

SMC
18v15

SMC
24v12

SMC
18v25

SMC
24v23

SMC G2
18v15

SMC G2
24v12

SMC G2
18v25

SMC G2
24v19
Minimum operating voltage: 5.5 V 5.5 V 5.5 V 5.5 V 5.5 V 6.5 V 6.5 V 6.5 V 6.5 V
Recommended max
operating voltage:
24 V(1) 24 V(1) 34 V(2) 24 V(1) 34 V(2) 24 V(1) 34 V(2) 24 V(1) 34 V(2)
Max nominal
battery voltage:
18 V 18 V 28 V 18 V 28 V 18 V 28 V 18 V 28 V
Max continuous current
(no additional cooling):
7 A 15 A 12 A 25 A 23 A 15 A 12 A 25 A 19 A
USB, TTL serial,
Analog, RC control:
Yes Yes Yes Yes Yes Yes Yes Yes Yes
I²C control: Yes Yes Yes Yes
Hardware current limiting: Yes Yes Yes Yes
Reverse voltage protection: Yes Yes Yes Yes
Dimensions: 2.1″ × 1.1″ 2.3″ × 1.2″ 2.1″ × 1.1″ 1.7″ × 1.2″
Price: $39.95 $44.95 $49.95 $59.95 $64.95 $39.95 $39.95 $49.95 $49.95
Available with
connectors installed?
Yes Yes Yes No No Yes Yes No No
1 30 V absolute max.
2 40 V absolute max.

Key features of the SMC G2 family

  • Simple bidirectional control of one brushed DC motor
  • Five communication or control options:
    1. USB interface for direct connection to a PC
    2. Logic-level (TTL) serial interface for use with a microcontroller
    3. I²C interface for use with a microcontroller
    4. Hobby radio control (RC) pulse width interface for direct connection to an RC receiver or RC servo controller
    5. 0 V to 3.3 V analog voltage interface for direct connection to potentiometers and analog joysticks
  • Simple configuration and calibration over USB with a free configuration program for Windows
  • Reverse-voltage protection
  • Hardware current limiting with a configurable threshold
  • Current sensing

Note: A USB A to Micro-B cable (not included) is required to connect this controller to a computer.

Additional features of the SMC G2 family

  • Adjustable maximum acceleration and deceleration to limit electrical and mechanical stress on the system
  • Adjustable starting speed and maximum speed
  • Option to brake or coast when speed is zero
  • Optional safety controls to avoid unexpectedly powering the motor
  • Input calibration (learning) and adjustable scaling degree for analog and RC signals
  • Under-voltage shutoff with hysteresis for use with batteries vulnerable to over-discharging (e.g. LiPo cells)
  • Adjustable over-temperature threshold and response
  • Adjustable PWM frequency from 1.13 kHz to 22.5 kHz (maximum frequency is ultrasonic, eliminating switching-induced audible motor shaft vibration)
  • Error LED linked to a digital ERR output, and connecting the error outputs of multiple controllers together optionally causes all connected controllers to shut down when any one of them experiences an error
  • Field-upgradeable firmware
  • Features of the serial, I²C, and USB interfaces:
    • Optional CRC error detection to eliminate communication errors caused by noise or software faults
    • Optional command timeout (shut off motors if communication ceases)
  • Serial features:
    • Controllable from a computer via serial commands sent to the device’s USB virtual serial (COM) port, or via TTL serial through the device’s RX/TX pins
    • TTL serial uses 0 V and 3.3 V on TX, accepts 0 V to 5 V on RX
    • Supports automatic baud rate detection from 1200 bps to 500 kbps, or can be configured to run at a fixed baud rate
    • Supports standard compact and Pololu protocols as well as the Scott Edwards Mini SSC protocol and an ASCII protocol for simple serial control from a terminal program
    • Optional serial response delay for communicating with half-duplex controllers such as the Basic Stamp
    • Controllers can be easily chained together and to other Pololu serial motor and servo controllers to control hundreds of motors using a single serial line
  • I²C features:
    • Compatible with I²C bus voltage levels from 1.8 V to 5 V
  • RC features:
    • 1/4 µs pulse measurement resolution
    • Works with RC pulse frequencies from 10 to 333 Hz
    • Configurable parameters for determining what constitutes an acceptable RC signal
    • Two RC channels allow for single-stick (mixed) motor control, making it easy to use two Simple Motor Controllers in tandem on an RC-controlled differential-drive robot
    • RC channels can be used in any mode as limit or kill switches (e.g. use an RC receiver to trigger a kill switch on your autonomous robot)
    • Battery elimination circuit (BEC) jumper can power the RC receiver with 5 V or 3.3 V
  • Analog features:
    • 0.8 mV (12-bit) measurement resolution
    • Works with 0 to 3.3 V inputs
    • Optional potentiometer/joystick disconnect detection
    • Two analog channels allow for single-stick (mixed) motor control, making it easy to use two Simple Motor Controllers in tandem on a joystick-controlled differential-drive robot
    • Analog channels can be used in any mode as limit or kill switches

As with all of our new products this year, we are offering an introductory special. Be among the first 100 customers to use coupon code SMCG2INTRO and get $10 off on up to three units (per version)!

New products: Shunt Regulators

Posted by Jan on 1 November 2018

When I think of a robot, I usually picture a mobile robot, which generally means it is powered by a battery. Most of our motor controller products are built with that kind of bias in mind, too. But there are obviously many permanent installations that still call for motion, from 3D printers and robot arms to kinetic sculptures and motion simulators. And powering those can be complicated and expensive, with power supplies capable of powering bigger motors often costing more than the motors and the motor controllers. One difficulty is that power supplies are often not particularly good for absorbing the little pulses of power that motors and motor controllers sometimes send back out (typically when a motor is slowing down). The ramifications can be very bad since the supply voltages can quickly get destructively high when the current has nowhere to go. Many better power supplies have over-voltage protection, but that just means the power supply shuts down. While that’s better than expensive parts going up in smoke, it can still keep your project from functioning.

The simplest solution to the problem is often a transient voltage suppressor, or TVS, which is a big zener diode optimized for handling big current spikes. Unfortunately, TVS diodes typically do not have a tight enough tolerance for use with power supplies with over-voltage protection. For example, a 12V power supply might have 5% tolerance, meaning the output voltage could be as high as 12.6V, so the protection device must not kick in below 12.6V. If the over-voltage protection is triggered by a 15% deviation, any voltage spikes must be kept below 13.8V. Most basic TVSes do not have tight enough tolerances to ensure operation in that window.

So, we developed a shunt regulator that should help with that kind of scenario. A simplified schematic diagram of the shunt regulator is shown below. Basically, a circuit monitors the voltage and controls a MOSFET that allows current to flow through a shunt resistance that sets the maximum current the device can sink.

Simplified schematic diagram of the Shunt Regulators.

We offer the shunt regulators with a variety of voltage set points and shunt resistances. Available variations include fixed resistances and multi-turn potentiometers for the voltage set point, different shunt resistances for the load, and different power ratings for the shunt resistance (the higher-power versions have twenty more resistors populated on the back side of the board).

Bottom view of the 3W and 9W Shunt Regulators.

Bottom view of Shunt Regulator: 13.2V, 1.50Ω, 15W.

One version of the shunt regulator is populated with an especially high shunt resistance with minimal power rating; this unit is intended for use with an external shunt resistance:

Shunt Regulator: 33.0 V, 32.8Ω, 3W.

The available versions are shown in the table below:

Voltage
13.2 V 26.4 V 33.0 V Fine-adjust LV Fine-adjust HV
Power 3 W #3780
32.8 Ω
9 W #3770
1.33 Ω
#3774
4.00 Ω
#3776
4.00 Ω
15 W #3771
1.50 Ω
#3775
2.80 Ω
#3777
4.10 Ω
#3778
1.50 Ω
#3779
4.10 Ω

This product is more for advanced users at this point since it can be difficult to determine how much power your motor is dumping back onto the power supply, but since we have the products working and several customers waiting to use them, we are going ahead with releasing them. We expect to develop additional resources and to put up verified regulator/motor controller combinations over time.

The basic regulators are quite inexpensive, and we are offering an introductory special as we are with all new products this year, so you might want to pick some up to play around with. The first hundred customers to use coupon code SHUNTREGS get 30% off on up to three units (per version).

New products: D36V6x step-down regulators

Posted by Jan on 31 August 2018

Pololu step-down voltage regulator D36V6Fx/D24V6Fx/D24V3Fx next to a 7805 voltage regulator in TO-220 package.

Wrapping up our new product releases for the month and for the summer is our new D36V6x family of step-down voltage regulators. These small regulator modules support a large input voltage range and are a great alternative to old three-terminal linear voltage regulators that waste a lot of power and get really hot. These new regulators can take an input voltage anywhere from a few tenths of a volt over the set output voltage up through an absolute max of 50 V, and they can deliver up to 600 mA. We have them available in seven fixed voltage options and two adjustable versions:

Pololu step-down voltage regulator D36V6Ax/D24V6Ax/D24V3Ax, bottom view with dimensions.

You might notice that the board for the adjustable version shows a 2010 copyright year (the fixed version is an even smaller board, and we did not fit the year on there). That’s because these new regulators are actually old designs updated with new regulator chips that use the same package and pinout. The older products were our D24V3x and D24V6x families of regulators, which were based on the Texas Instruments LMR14203 and LMR14206 ICs. For the new D36V6x family, we are moving up to the newer LMR16006 regulator. This chip has several exciting new features that we think will make it our favorite general-purpose regulator for many of our products: higher maximum voltage, better low-dropout performance, and better quiescent current.

Higher maximum voltage

The LMR16006 has a 60 V maximum input voltage, up from the 42 V of the LMR1420x parts. Even 42 V covered most of our typical applications, but it’s not quite enough for 36V nominal applications, which are getting more common. Our more advanced, integrated products such as motor controllers are often limited by some complex part or circuit, such as a motor driver, and we would like the overall operating range of the product not to be reduced by the regulator. Many stepper motor drivers, such as TI’s DRV8825 or the Toshiba TB67S249FTG and TB67S279FTG that we released carriers for in June, support maximum input voltages of 45 or 50 volts. It’s nice not to be limited by your regulator when you are making systems with those kinds of parts.

For our new D36V6x modules, we are limited to the 50 V maximum of the capacitors from Vin to ground. Unfortunately, capacitor options get a lot more restricted (and expensive) once we go beyond 50 V, so we decided to stick with our old boards so that we could continue to offer these regulator modules at a low price while still providing some substantial improvements. We might still make a new board with higher-voltage capacitors for those who would like to make full use of the regulator’s 60 V maximum. (For anyone thinking of just removing the caps and putting on your own external ones, you might also want to change the diode, which is also a 60 V part.)

Better low-dropout performance

Having a higher maximum input voltage is nice, but often we’re trying to squeeze the most we can out of a dying battery, so it’s nice to have a low dropout, which is the voltage the regulator needs between the input and output. The older LMR1420x parts had an annoying quality of the dropout voltage going up as the load current went down. The newer LMR16006 has a nice, low dropout as the current goes down, so if you don’t need much current, you can get 5 V out with just 5.2 or 5.3 volts in. Here is a comparison of the dropout performance of the old and new regulators:

Typical dropout voltage of Pololu step-down voltage regulator D24VxF5.

Typical dropout voltages of Step-Down Voltage Regulator D36V6Fx.

Lower quiescent current

The new regulators also have much lower quiescent current, which is the current the regulator uses when it’s just sitting there and your load isn’t drawing anything. On the old regulators, the quiescent current was under 2 mA, and we did not characterize it beyond that. For these new regulators, it’s typically under 200 microamps, ten to twenty times better than the old regulators. I realize it’s not that amazing for modern regulators, but it’s nice to know that your low-cost, general-purpose regulator module isn’t wasting a lot of power.

Typical quiescent currents of Step-Down Voltage Regulator D36V6Fx.

Even when we put a new chip onto an old circuit board as I have described, we still test and characterize with different parts to get a good overall result. In the case of these regulators, where the circuit is quite simple, this phase of development is much more time consuming than laying out a circuit board. We build and test dozens of prototypes with different inductances, and even though you can’t see it in the pictures, we build the different voltage versions of the regulators with different inductors to get the best performance we can (within a given inductor type and size).

So how about getting a few to have around for general-purpose use on your next project? You can get one for just $3 as part of our introductory promotion using coupon code D36V6XINTRO, limited to the first 100 customers and to three per item (so you could get up to 27 regulators at that price if you get three of each voltage version). It’s always difficult for us to predict which versions will be how popular, so initial stock is limited, but we make these here in Las Vegas, so even if the version you want goes out of stock, you can backorder it with the promotional price, and we should be able to ship within a day or two.

New products: 1- and 31-channel QTR HD reflectance sensor arrays

Posted by Jan on 31 August 2018

This week, we released what we expect to be the extremes of our new line of QTR HD reflectance sensor arrays, with two sizes of a single-sensor board on the small end and a massive 31-sensor array for the maximum size. This picture shows the relative sizes of the boards, along with some of the intermediate sizes we have available:

The QTR Reflectance Sensor Arrays are available in many different sizes.

We made the two single-sensor sizes because we could make good arguments for each one. Part of the point of doing a single-sensor board is to make it really small, so you can fit it into tight spaces. But “really small” means different things depending on the dimensions you care about. So we have one version that is only 5 mm (0.2") wide, with components on both sides of the PCB, and one version that is 7.5 mm (0.3") wide, with components on just one side. The 7.5 mm wide version is a little thinner and flatter because it doesn’t have parts on one side, can be used with a 3×1, single row connector, and costs slightly less because of the single-sided assembly.

QTRX-HD-01RC Reflectance Sensor, front and back views.

QTRX-MD-01A Reflectance Sensor, front and back views.

As I mentioned in some of my earlier posts (here and here) about this new line of sensor arrays, we are using two sensor types: more economical units we are calling “QTR”, and higher-performance units with lenses that we are calling “QTRX”. The main appeal of the QTRX sensors is that they can give the same readings at much lower IR emitter currents, which can really make a big difference for big sensor arrays. But if you crank up the current in those QTRX sensors, you can also get more distance. We did not do that on the QTRX arrays because the sensor modules leak light out the sides and interfere with each other when they are closely spaced, but with these single-channel boards, we are also making available the QTRX sensors with the higher 30 mA maximum emitter current, which allows for a range of up to about 8 cm (about 3 inches). We are calling these sensors QTRXL.

This video (taken with an old camera that does not have as much IR filtering as most newer cameras) shows the IR light leakage around the side of the QTRX sensor module:

I should point out that all of these new QTR modules offer variable brightness control by varying the current through the emitter using the control pin. However, if you want to take advantage of the maximum brightness and range, and have several sensors close to each other, you will need some barriers between them to prevent them from blinding each other (or just turn on one emitter at a time).

The 31-sensor arrays are huge! Well, at least compared to the tiny single-sensor boards.

QTRX-HD-31RC Reflectance Sensor Array.

The routing on those boards is quite complex because adjacent IR emitters are not just wired in series (because we want to have separate even/odd emitter control, plus the alternate density population options I discussed in this post), so we ended up having to go to a 4-layer PCB to route it. This did let us make the vertical dimension a little lower, so the board is just 16.5 mm tall, compared to the 20 mm board height for the versions with 15 and fewer sensors. The 31-channel board is also 0.062" (1.6 mm) thick, compared to the thinner 0.040" (1 mm) boards we use for the lower channel counts. You can compare all the dimensions of the various boards in the detailed dimension diagram (1MB pdf).

The sixteen new boards we released this week brings the total available in this new QTR HD product line to 40. You can see the options neatly summarized in the tables below to pick the best array for your application.

QTR sensors
2.9 V to 5.5 V; 30 mA max LED current(1); 5 mm optimal range
Board
width
Configuration Max board
current(2)
Max range Output
type
Name 1-piece
price
5.0 mm 1 sensor (HD)
32 mA 30 mm analog QTR-HD-01A $1.79
RC (digital) QTR-HD-01RC
7.5 mm 1 sensor (MD)
32 mA 30 mm analog QTR-MD-01A $1.61
RC (digital) QTR-MD-01RC
10.2 mm 4 mm × 2
32 mA 30 mm analog QTR-HD-02A $2.12
RC (digital) QTR-HD-02RC
17.0 mm 4 mm × 4
62 mA 40 mm analog QTR-HD-04A $3.26
RC (digital) QTR-HD-04RC
29.0 mm 8 mm × 4
62 mA 40 mm analog QTR-MD-04A $3.44
RC (digital) QTR-MD-04RC
4 mm × 7
125 mA 40 mm analog QTR-HD-07A $5.40
RC (digital) QTR-HD-07RC
61.0 mm 8 mm × 8
125 mA 40 mm analog QTR-MD-08A $6.39
RC (digital) QTR-MD-08RC
4 mm × 15
250 mA 50 mm analog QTR-HD-15A $10.82
RC (digital) QTR-HD-15RC
125.0 mm 4 mm × 31
495 mA 50 mm analog QTR-HD-31A $21.66
RC (digital) QTR-HD-31RC
QTRX sensors
2.9 V to 5.5 V; 3.5 mA max LED current(1); 10 mm optimal range
Board
width
Configuration Max board
current(2)
Max range Output
type
Name 1-piece
price
5.0 mm 1 sensor (HD)
5 mA 30 mm analog QTRX-HD-01A $2.17
RC (digital) QTRX-HD-01RC
7.5 mm 1 sensor (MD)
5 mA 30 mm analog QTRX-MD-01A $1.99
RC (digital) QTRX-MD-01RC
10.2 mm 4 mm × 2
5 mA 30 mm analog QTRX-HD-02A $2.88
RC (digital) QTRX-HD-02RC
17.0 mm 4 mm × 4
9 mA 40 mm analog QTRX-HD-04A $4.78
RC (digital) QTRX-HD-04RC
29.0 mm 8 mm × 4
9 mA 40 mm analog QTRX-MD-04A $4.96
RC (digital) QTRX-MD-04RC
4 mm × 7
17 mA 40 mm analog QTRX-HD-07A $8.06
RC (digital) QTRX-HD-07RC
61.0 mm 8 mm × 8
17 mA 40 mm analog QTRX-MD-08A $9.43
RC (digital) QTRX-MD-08RC
4 mm × 15
34 mA 50 mm analog QTRX-HD-15A $16.52
RC (digital) QTRX-HD-15RC
125.0 mm 4 mm × 31
68 mA 50 mm analog QTRX-HD-31A $33.44
RC (digital) QTRX-HD-31RC
QTRXL sensors
2.9 V to 5.5 V; 30 mA max LED current(1); 20 mm optimal range
Board
width
Configuration Max board
current(2)
Max range Output
type
Name 1-piece
price
5.0 mm 1 sensor (HD)
32 mA 80 mm analog QTRXL-HD-01A $2.17
RC (digital) QTRXL-HD-01RC
7.5 mm 1 sensor (MD)
32 mA 80 mm analog QTRXL-MD-01A $1.99
RC (digital) QTRXL-MD-01RC
1 Can be dynamically reduced to any of 32 available dimming levels.
2 With all LEDs on at max brightness setting.

Our introductory promotions are still going strong! Be one of the first 100 customers to use coupon code QTRINTRO and get any of these new sensors at half price! (Limit 3 per item per customer.)

New products: Robot Arm Kit for Romi (and also just the gripper)

Posted by Jan on 30 August 2018

I’m super excited to announce our newest product, the Robot Arm Kit for Romi. The Romi arm is designed to mount to the back half of a Romi chassis with two fixed servos controlling the height and angle of the gripper through a nifty linkage system.

The Romi with Robot Arm and various electronics to enable RC control.

Side view of the Romi with Robot Arm and various electronics to enable RC control.

The gripper itself uses a micro servo with two parallel fingers or paddles that open and close through a rack and pinion arrangement. Here is a quick video demonstration of a Romi chassis with the arm attachment:

You can see the available range of motion in the drawings below:

Range of motion of the height of the Robot Arm for Romi.

Range of motion of the wrist tilt on the Robot Arm for Romi.

Range of motion of the gripper on the Robot Arm for Romi.

The kit ships with all mechanical parts, including special servos with a fourth wire for reading the position of the output shaft:

Contents of the Robot Arm Kit for Romi.

We are also making the gripper used on the arm available as a standalone Micro Gripper Kit with Position Feedback Servo. Here is a picture of the assembled gripper:

Fully assembled Micro Gripper with Position Feedback Servo.

Products like this arm kit, with many injection-molded components, are some of the most complicated and time-consuming products we make. As those of you who have followed our growth over the past decade are probably aware, we try to develop our more complete robot kits incrementally, starting with components like just a wheel or a motor bracket, and then using those components in the more integrated robots. For example, we came out with this line of wheels in 2010:

Pololu wheels with 90, 80, 70, and 60mm diameters in three colors: blue, red, and yellow.

The Romi and Balboa robots, which use those wheels, did not come out until 2016 and 2017.

Romi Chassis Kit – Blue.

One of the many possible configurations of the bumper cage on the Balboa 32U4 Balancing Robot.

If you look at the parts that go into just the gripper portion, you can see that each of the components is roughly as complicated as one of those wheels, and you can’t really do much with just one of those parts:

Contents of the Micro Gripper Kit with Position Feedback Servo.

So, a lot of work goes into designing these kits. We also do not machine the molds or do the injection molding in-house (we did that on the first few parts for the 3pi robot), so that adds a lot of delays compared to our electronics boards, which we make in the same building that we design them in. We do 3D print prototypes to maximize the chances that we get the designs right, but there are invariably little modifications that we end up having to make when the components are this complicated, which is why it takes us years to go from the initial idea to the released kit.

We are at least sticking to our incremental product release approach as far as integration with electronics goes: at the time of the Romi arm attachment release, we do not have a specific solution for controlling the robot, which we will be working on next. Therefore, this kit is currently intended for advanced users who are comfortable powering and controlling several servos on their own.

As with all of our new product releases this year, we are offering substantial introductory discounts for the first customers to try out our new designs. You can use coupon code ROMIARMINTRO to get the whole arm for just $49 and code GRIPPERINTRO to get just the gripper for only $13. Each coupon is limited to 100 uses and 3 units per customer.

New products: more new QTR HD sensor arrays by student engineering interns

Posted by Jan on 23 August 2018

All the student engineering interns we had over the summer from out-of-town colleges are headed back to school, so I get to announce the release of products they worked on over the summer. The new QTR sensors we are releasing today include the 15-channel version laid out by seventeen-year-old Chris H.

Hadouken! (2018 summer engineering intern Chris couldn’t come up with a clever pun to use for this picture of him posing with a circuit board he designed.)

You can see more about our new line of QTR reflectance sensor arrays in the first blog post I wrote about them a few weeks ago. One cool design and manufacturing aspect I did not mention then is that we designed these boards so that they could be populated at various densities. For example, that lets us make an 8-channel version with 8 mm sensor pitch on the same board that also works as a 15-channel array with 4 mm sensor pitch:

QTRX-MD-08RC Reflectance Sensor Array.

Here are some diagrams showing some of the thought that went into the soon-to-be released 31-channel version, which can also be populated to be an 8 mm pitch, 16-sensor array; a 12 mm pitch, 11-channel array; and a 20 mm pitch, 7-channel array:

Diagram of emitters and drivers on a QTR-HD-31x sensor array board with all sensors populated.

Diagram of emitters and drivers on a QTR-HD-31x sensor array board with 1/2 sensors populated.

Diagram of emitters and drivers on a QTR-HD-31x sensor array board with 1/3 sensors populated.

Diagram of emitters and drivers on a QTR-HD-31x sensor array board with 1/5 sensors populated.

With so many combinations of sensor types and output circuits, we won’t make every one of the possible arrangements a stock product, but the idea is that if you have an application where a particular sensor pitch is ideal for you, we can quickly make some for you without having to lay out new PCBs.

We expect eight channels on an 8 mm pitch to be a popular variant, so those will be stock products. We have also added the corresponding 4-channel version (using the same boards used for the full-density, 7-channel product), so this new product announcement covers twelve new stock sensor arrays:

QTRX-HD-15RC Reflectance Sensor Array.

QTRX-MD-08RC Reflectance Sensor Array.

QTRX-MD-04RC Reflectance Sensor Array.

Our introductory promotions are still going strong! Be one of the first 100 customers using coupon code QTRINTRO and snag any of these new sensors at half price! (Limit 3 per item per customer.)

New products: U3V70x high-current boost voltage regulators

Posted by Jan on 16 August 2018
Tags: new products

Today we are finally releasing our new U3V70x family of boost regulators, which are now our highest-current boost regulators. (I said “finally” because we have had the boards designed for over six months, but we just finally received the main ICs for our production builds even though I ordered them last year.) Besides supporting the most current of any of our boost regulators, we also have an adjustable version with a multi-turn trimmer potentiometer, which makes setting the output voltage to a particular value much easier than when the whole output voltage range is represented by the 250 degrees or so of a single-turn pot. The regulators operate with input voltages down to 2.9 V, and the adjustable output version can be set to an output in the range of 4.5 V to 20 V. Talking about the current on boost regulators is tricky since it’s so dependent on input and output voltages, so it’s best to just show you a few performance graphs:

Typical efficiency of Step-Up Voltage Regulator U3V70x, Vout = 12V.

Typical maximum continuous output current of Step-Up Voltage Regulator U3V70x.

For those who don’t need adjustability (that multi-turn pot is expensive!), we offer fixed-voltage versions in six standard voltages:

We can also make customized fixed versions for you with other voltages between 4.5 V and 20 V.

Comparison of the newer U3V70A boost regulator (top) to the older U3V50ALV (bottom).

It’s exciting that these new regulators are smaller than what used to be our highest-power boost regulator (the U3V50x family) despite handling more current. One way we kept the size smaller is by using only ceramic capacitors. One consequence of that is that the new regulator outputs are slightly noisier, so if that is important for your application, you might want to add some external capacitors to further smooth out the voltage. The older design also supports a higher maximum output voltage, so if you need more than 20 V, our U3V50F24 fixed 24 V and U3V50AHV adjustable 9 V to 30 V units are still our highest-power options.

As with all our new products this year, we are offering a special introductory promotion. You can get up to three of each version for just $9 (which is an especially good deal for the adjustable regulator!), limited to the first 100 customers using coupon code U3V70XINTRO.

New product: high-density QTR reflectance sensor arrays

Posted by Jan on 31 July 2018
Tags: new products

I am excited to announce the first of a new line of reflectance sensor arrays that feature a high-density 4-mm pitch and dimmable IR emitter brightness control. In addition to versions with our familiar IR emitter/phototransistor pair modules without lenses, which we will keep calling “QTR,” we have versions with a higher-performance sensor with lenses on the IR emitter and phototransistor, which we are calling “QTRX.” These higher-performance sensors allow similar performance at a much lower IR LED current, which can really start adding up at higher channel counts. (High-brightness, “QTRXL” versions of these boards are coming soon, too.)

These new sensor arrays also feature LED brightness control that is independent of the supply voltage (which can be 2.9 V to 5.5 V) and separate controls for the odd-numbered LEDs and the even-numbered LEDs, which gives you extra options for detecting light reflected at various angles. As with our older QTR sensors, we are offering these in “A” versions with analog voltage outputs and “RC” versions that can be read with a digital I/O line on a microcontroller by first setting the line high and then releasing it and timing how long it takes for the voltage to get pulled to the logic low threshold:

Schematic diagrams of individual QTR sensor channels for A version (left) and RC version (right). This applies only to the newer QTRs with dimmable emitters.

This announcement therefore covers four total new products:

As with all our new products this year, we are offering a special introductory promotion, and this one is for half off up to three of each sensor type, limited to the first 100 customers using coupon code QTRHD07INTRO.

New Products

Shunt Regulator: 26.4V, 4.00Ω, 9W
High-Power Simple Motor Controller G2 18v25
MCP233 Dual 30A, 34VDC Advanced Motor Controller
Shunt Regulator: Fine-Adjust HV, 4.10Ω, 15W
Shunt Regulator: 33.0 V, 32.8Ω, 3W
Shunt Regulator: 33.0V, 4.00Ω, 9W
MCP2163 Dual 160A, 34VDC Advanced Motor Controller
MCP266 Dual 60A, 60VDC Advanced Motor Controller
High-Power Simple Motor Controller G2 18v15
Shunt Regulator: 33.0V, 4.10Ω, 15W
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