Dagor Controller Question + Purchase Inquiry

Hello, I am interested in the Dagor Brushless Controller, but it doesn’t seem that there is a current alpha stage. Also, I was wondering what the voltage maximum was because one document appeared to be 24V and another read 34V. Also, I was curious why the more expensive as5147 was used over as5047, as they seem to be functionally equivalent. Thank you, Josh

Hey Josh,

Unfortunately the chip shortage is affecting the production of more Dagor Alpha Boards for now, as soon as I’m able to produce more I’ll make sure to notify the people that has shown an interest. :slight_smile:

Can you point to me where does it say 34V? I rated the board for 24V to be on the safe side, I’ve briefly tested the board at 30V, but a lot more testing would need to be done to change the rating. Also, I’m using the AS5147 mainly because it’s a newer chip and because at quantity the price difference is small.

From other pages I have read, it seems that manufacturing is halted because JLCPCB does not stock the motor driver. I was wondering if it would be possible to either A - order the board through pcbway who will source components as necessary, or B - order the board through JLCPCB without dev driver but with exposed pads, and to manually solder after with solder paste. Do you think wither of these alternatives are viable? I am very keen on obtaining the driver soon as Summer allows me time to work on my side project. Thank you.

Obviously I cannot speak for David however if I were to manufacture the Dagor board with pcbway it would cost between $100 and $200 per completed board for a 10 board batch depending on time and component availability. Usually these types of small boards take 4 weeks from paper to product.

Another option is to order the fabrication through a Silicon Valley facility, and the price is about the same but they can turn it around in 10 days assuming the components are available through one of the major US retailers.

If you source the components yourself, this type of board would cost about $300 per completed board since it takes about four hours per board to SMD and reflow and test in such a small batch. Which means for a minimum 10 board batch, I need to find 10 people to buy it at $300/board before I even make any profit.

Are you willing to pay $300 per board if you need it in less than a month?

Cheers,
Valentine

Forgive my ignorance, as I am fairly new to this, but I was curious how manufacturing through JLCPCB with everything could be about 40 euros while manufacturing without drv motor driver could be prohibitively expensive. I’d be able to justify buying a batch of 10 as I am looking to build a quadruped. It looks like buying one drv driver for the board would be less than 10$ so I’m curious how this isn’t affordable.

@JJSmooth,

I understand your question. You cannot fabricate with only one component missing, it’s either all or none, especially with a two-sided SMT. It is perhaps possible to fabricate without a small component or a component that is topologically isolated you can heat up with a soldering iron however if you manufacture without an LQFP component right in the middle which requires a solder mask for the paste you cannot place the solder mask for the itty-bitty holes because the other components will get in the way. And then when you heat the component to solder it, the other near components will also heat up and de-solder, and the sensor on the back will plop down off the surface and your board will be destroyed. I’ve seen people performing black magic and SMT hand soldering some very tricky designs however this requires years of experience, the fine motor skills of a neurosurgeon and very expensive equipment, and these people are usually worth over $100/hour and they are not hobbyists, they work for some of the large companies, like Intel, TI, SM or the likes.

JLCPCB and all other PCB fab facilities use robots to manufacture the boards. Your board file is loaded into the machine, the components are picked and placed by a robotic arm with a micrometer precision, and then tested again with a robot, which can process hundreds of boards an hour. That’s why it is so cheap. You do thus by hand and you are looking into a few hours per board.

I have the good fortune of living and working close to a few world-class PCB fabrication facilities, if you are really that determined, I may go in person to ask them if they are willing to run a small batch, and if they can source the components. I cannot promise anything however due to Covid restrictions, this is more of a “may or may not work” type of a situation. Disclosure, I’ve never worked with them, nor do I work for them.

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Alright, makes sense. Thanks very much for the info! I’ll look into making a board with parts that JLCPCB has in stock, or figuring out how to get JLCpCB to stock the driver.

@JJSmooth

It appears that David Gonzales knows what he is doing, may be wait for him to give you input?

I forgot to link where it suggested 34V. Its in the Power Stage section of documentation. Maybe I interpreted it incorrectly.

Ok, having made quite a few boards with PCBWay by now, I have to disagree a little bit with some points of the above discussion:

  • Firstly, it is absolutely no problem to have boards produced and assembled with missing components. They will put exactly the components you specify in your BOM at the location specified in your centroid file, and anything you leave out of the BOM simply won’t be placed.

  • But as Valentine mentions, whether you can realistically add a missing component into the middle of an otherwise assembled design is something you have to consider quite carefully. Its not like there is a lot of space on Dagor :smiley: if you just go in there with the hot air, you’ll melt everything else off the board… Still, there is always Kapton Tape, and I know for fact that some people have successfully de- and re-soldered the ESP32 module onto it…

  • You only pay for what they order, so the parts that aren’t placed won’t cost you anything. Their prices for the chips and passives are generally quite competitive, certainly by the time you pay for postage sending them around their prices will be cheaper for small batches.

  • 3-4 weeks for assembly is about right, but with the semi conductor shortage right now it could be a bit longer. The longest part is always them ordering and waiting for your parts.

  • The price for a small batch assembly depends critically on your board meeting certain criteria: 1-4 layers, no complicated HDI stackups. Basically if you can use only through hole vias, and keep it to 1-4 layers, and don’t exceed their component limits, and need less than 20 pieces produced, then you will get the $30 assembly deal. So for a board the size of Dagor (I’m assuming now it doesn’t need complex HDI stuff), you will pay $30 for assembly + the PCBs + the components. I’m guessing it will come to between $200-$400 in total for a batch of 10. So more like $20-$40 per board + shipping + any duties applicable in your jurisdiction.

  • As an example, my last motor driver board (considerably less components than dagor, but similar kind of size) cost me $348 + shipping – for 20 pieces.

  • Plus, if it’s your first time with them they can be quite generous, the PCBs might be free…

But this is all academic, because AFAIK Dagor isn’t available as open source for self-production. You’ll have to keep reminding David! Or send him some chips :slight_smile:

If you have available a soldering iron, hot air gun and some kind of microscope like this o similar with a little bit oaf practice and patience you can manually assemble your boards. Without having a some kind microscope I would not venture to manually assemble.

If there are certain components that could not be available at JLCPCB/LCSC you can always look for them in AliExpress … it is a more risky option and you have to be careful because they don’t always sell you what they say they are selling but if you are not unlucky it is an alternative source.

I will recoment to built a DIY reflow oven. If you need a processing app. and arduino program here it is: https://github.com/Juanduino/ReflowAwe-101. You need a small oven with fast heating heat-elements (cant recall their name). It should be insulated with fire-fabric (glass-fiber blanket normally used as a safety precaution for burning oil) and you neet a beefy solid state relay, high temp probe + amplifyer to go with the uno or teensy. The insulation goes on the inside of the oven enclosure, not inside the oven itself. You can do 0402 components by hand but it is a pain. Definitely use a stencil for the solder paste.

No experience with pcbway, however, jlcpcb does that, no problem, you are correct.

Interesting, the design is closed, that’s something I didn’t know. I always assumed the dagor github had the full schematics. In this case @JJSmooth ordering himself a board batch with some or all components omitted is not an option. Pithy.

Sure you could make your own Dagor clone, but it would be hard to make it as small as the original.
It looks like a 4 ( or perhaps 6 ) layer board and it has got all these tiny 402 components.
But looking at the board it’s obvious what it does. You can put all the components in a drawing and guess most of the connections. Many are visible at the surface layers anyway.