Here is yet another new product announcement! In the same line as the new pi3hat, here is a new minor revision of the power_dist, the r4.5b:
The changes are largely the same as for the new pi3hat:
Check it out at mjbots.com today!
Here’s yet another update to the moteus line, moteus r4.11!
r4.11 is electrically, mechanically, and software compatible with r4.3, r4.5, and r4.8.
This revision supports two alternate footprints for the CAN-FD transceiver to better support component availability and refines the power stage for the DRV8353 gate driver. moteus r4.8 was the first version to use the DRV8353 because of, once again, component availability issues. However, it was developed on a very abbreviated schedule. With r4.11 the EMI is much improved over r4.8 and r4.5, and the efficiency is much better than r4.8 at all input voltages and PWM frequencies.
| PWM Frequency | 24V r4.11 | 24V r4.8 | 36V r4.11 | 36V r4.8 |
| 15kHz | 95% / 0.28W | 94% / 0.20W | 95% / 0.30W | 92% / 0.25W |
| 40kHz | 93% / 0.35W | 88% / 0.25W | 90% / 0.38W | 85% / 0.30W |
| 50kHz | 91% / 0.36W | 84% / 0.30W | 89% / 0.40W | 84% / 0.35W |
The matching development kit will be available shortly, once the r4.8 developer kits sell out.
I’m excited to announce the release of moteus r4.8!
Due to the ongoing semiconductor apocalypse, this minor release uses some alternate components which were easier to source. It remains compatible with the r4.5 and r4.3 both electrically, mechanically, and with firmware.
For now, the biggest win is that the board and the devkit are actually in stock!
A secondary win is that external primary encoders are now supported, via an unpopulated connector pad on the backside of the board. I’ll write up more about that in a later post.
Good luck building!
In what probably won’t be the last time, mjbots.com now has a new version of the pi3hat due solely to component shortages!
There are no top-level feature changes versus the previous r4.4. What is different is that the connector for the Raspberry Pi has reverted to the fixed height version that the r4.3 and earlier used, and the IMU is slightly better.
Happy building!
There are a lot of steps necessary to get a product to market, not just a fancy render. I admit to being far from covering all the bases yet, but we’re getting there. In that spirit, I recently upped the packaging game of the qdd100 with some custom boxes and foam inserts. Pick one up at mjbots.com!
I’d like to introduce the newest mjbots product, an updated revision of the power_dist, 4.3b available at mjbots.com today!
This version has a number of improvements over the previously released r3.1:
| r4.3b | r3.1 | |
| Voltage Range | 10-44V | 8-34V |
| Maximum load capacitance | 4,000 uF | 400 uF |
| Quiescent Current | 300uA | 5mA |
| Current (Continuous / Peak) | 45A / 80A | unrated / 100A |
| Energy Monitoring | YES | NO |
| Switch Mode | High Side | Low Side |
| Dimensions | 50x80mm | 45x70mm |
| Price | $139 | $79 |
The only real downsides are that is more expensive and slightly larger.
If you want to read up more on the motivation and design process for this board, you can see that in (part 1, part 2, part 3, part 4).
mjbots.com had a week long run where we were completely out of fdcanusbs, which meant that we were also out of all development kits too. Well, a production run just came in:
So now we’ve got everything back in stock once again!
It seems like all the posts I’m writing these days are for new products! Here’s the pi3hat r4.4:
There are two changes from the previous r4.2. First, it now supports voltage inputs up to 44V. Second, in support of future upgrades, the 5th CAN-FD port has been upgraded to support 8Mbps, but downgraded to no longer have a wide common mode voltage range.
THUS, IT IS NOT SAFE TO CONNECT THE CAN-FD PORT ON THE pi3hat r4.4 TO A power_dist r3.X BOARD.
Also, it is in stock at mjbots.com!
That said, the worldwide electronic supply chain is still in shambles. That combined with the Chinese New Year means that stock may be intermittent, and slight alternate versions to adjust to different parts may be forthcoming.
I’d like to introduce the qdd100 beta 2!
This is the newest version of a quasi-direct-drive servo from mjbots. It has a sleek new look, and improved performance all around:
| Beta 1 | Beta 2 | |
| Peak Torque | 12.5 Nm | 16 Nm |
| Backlash | +- 0.2 degrees | +- 0.1 degrees |
| Voltage Range | 10-34V | 10-44V |
| Mass | 470g | 475g |
Additionally, the M3 mounting holes are now 3mm deep instead of the previous 2mm, which gives more flexibility when designing mounts.
It is in stock at mjbots.com now, with more production becoming available in the next weeks and months.
Welcome to the newest mjbots.com product, the mj5208:
This is a high quality 5208 sized 330Kv wound brushless motor with short pigtails intended to connect to moteus controllers. All the moteus devkits as of last week are shipping using this motor instead of the previous “semi-random” motor.
Specifications:
There are two bolt patterns on the output, a 3x M3 17mm diameter one, and a 2x M3 pattern spaced at 12mm. The stator side has a 4x M3 pattern spaced at 25mm radially and a 3x M2.5 spaced at 32mm. The axle protrudes a few mm from the stator, making it easy to adhere the diametric magnets needed for moteus.
A Modicum of Fun 