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Old Jun 08, 2013, 08:56 PM
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Mesa Falcon Fld, Arizona, United States
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Microgyros,

I do not want this to come off rude, but I went through most of your posts on RCG, and I could not find any mention of a speed controller that was even close in size to what I have. I am not saying that they do not exist, just the ones that I have come across have been poorly designed, or over rated for their current capacity. I did go to your home page, and while it does look like you have some nice products, I did not see anything that was in this product range. Perhaps I missed it, but to have something that was half this size would be quite a feat indeed (6mm x 7mm). I would love to see your product. It would give me a challenge to make something even smaller

I am just not sure how you would get that much smaller. I have been looking at going with discrete components to get the Rds(on) down by an order of magnitude so as to reduce the space needed for board space to deal with the thermal issues, but then I would go from an integrated H-bridge with thermal and over current protection built in at 2mm x 2mm to a solution that with the discrete mosfets alone would be no smaller than 4mm x 3mm. This does not even include any resistor arrays for current measurement and no dedicated thermal protection. The other limiting factor is the LDO. I could go about half the size as currently used if I were to go to to a BGA solution, but most of those do not allow for 2s voltage. I think that I did find one that was a 2mm x 3mm DFN, which would have reduced the board space a bit, but would not have allowed me to have the 3s capacity if I ever wanted it. The other thing that I could have done is gone with a resistor array for the voltage divider for low voltage detection, but this would not have afforded me the flexibility that I currently have, being able to swap out resistors to alter the divider ratio. Right now all resistors and caps are 0402 packages, I am not quite up to trying to do 0201 packages for any sort of production work

Anyway, I would love to hear your thoughts on how to get a 6mm x 7mm sized micro speed controller.
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Old Jun 08, 2013, 09:14 PM
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Glasgow
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Adam,here is your one paragraph again.

Quote:
Originally Posted by Aeroengineer1 View Post
Derk, the other board is a completely different project. It is not near as far along in the code development as the micro ESC. I have yet to actually build one up. It is a micro pitch leveler that can fit into my small 144th scale Type 206 sub. None of the ones currently on the market will fit in that boat. Why should I go without one when I can design one myself. I am not sure that one will be commercially viable. Some of the components are not cheap on it. This was the trade to get the size down. When completed, the board will measure .55" x .55" (14mm x 14mm).
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Old Jun 08, 2013, 09:58 PM
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Ah, yes, the pitch controller. Yeah, it is a little larger than I wanted, but part of it was to allow me to use a dsPIC. They are a bit larger than I would like, but I needed a project to learn on. It also is using a 6 axis sensor. Eventually, though not anytime soon, I will be doing a Kalman filter to go with it, hence the dsPIC. For now, to get it to work in my boat, I am going to get going with a simple complimentary filter. Some of the other things that made it larger is that it still has test pads for both ICSP as well as access to the SPI lines. I have been looking to potentially move to the ARM Cortex line. There are some smaller chips that I could potentially look at going with. The other thing is that this is not only going to have a pitch leveler, but it will also have mixing for an X-tail boat, so this required 4 connectors in place of 2. That change alone would have made the board about half the width. The nice thing is that it can be mounted in pretty much any position and still function. This will facilitate the installation quite a bit.

Adam
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Old Jun 08, 2013, 11:15 PM
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Glasgow
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The AST2 mini pitch controller works well in X-tail boats with the TURNIGY mixer ultra small available from Hobbyking at $2.95.
There is no wait.They have been on sale since early 2012.

Back to micro escs.
Tom's two bidproduct escs which self destructed in his Aluminaut thread (where you announced) were only building blocks and not escs.
I told Marius on the 30th of January that the esc module would work on Tom's bench but will eventually blow up due to a missing part.
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Old Jun 09, 2013, 12:22 AM
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Mesa Falcon Fld, Arizona, United States
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I took a look at the solution you recommended, and the connectors alone for the mixer are almost the size of my full board. Like I said, I am not sure that I would ever sell any, but I will build up 2 or 3 for my projects. It is more of a project that I needed a mixer, I wanted to play with the dsPIC and I wanted to play with the 6DOF chip, so combine all of that and you get a pitch leveler. After that, and reading through a few more of my text books, I will attempt to implement a Kalman filter. This is all part of a larger plan, but it is being done in small chunks while producing components that I can use in my current projects.

As to the ESC's that failed in Tom's boat; they are specifically marketed as ESC. It seems like they should have worked (if the specs are even close on their website), unless at just less than 3.5V the mosfets were operating in the linear region. I suppose that could be happening.
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Old Jun 09, 2013, 12:32 AM
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Quote:
Originally Posted by microgyros View Post
The AST2 mini pitch controller works well in X-tail boats with the TURNIGY mixer ultra small available from Hobbyking at $2.95.
There is no wait.They have been on sale since early 2012.

Back to micro escs.
Tom's two bidproduct escs which self destructed in his Aluminaut thread (where you announced) were only building blocks and not escs.
I told Marius on the 30th of January that the esc module would work on Tom's bench but will eventually blow up due to a missing part.
I do not understand, even when I contacted the company that sold it, they confirmed they are escs. So what do you mean by building block and what is missing?
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Old Jun 09, 2013, 02:36 AM
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Adam,whether your own project is for commercial sale or for your own use is not an issue for me and I am not offering any comment on that.I entered this thread with a specific point that there IS one already on the market that fits that boat and ones half the size again in existence.

Tom,the circuit is ok up to a point.If you lengthen the power supply wires without soldering a capacitor close to its feed then it will self destruct.
To me it is a building block whatever the supplier says.
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Old Jun 09, 2013, 04:18 AM
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Listen to Mike on this one chaps, he's forgotten more than anyone else on this forum knows about electronics.
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Old Jun 09, 2013, 07:22 AM
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Mesa Falcon Fld, Arizona, United States
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Subculture,

Is is not that anyone is not trying to listen, it is just that we are just trying to understand what he is saying. We have been trying to ask questions to understand, that is all. His posts are somewhat cryptic (I am not trying to be derogatory here, his posts are jus a bit hard to understand due to lack of info).

Adam
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Old Jun 09, 2013, 10:16 AM
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Quote:
Originally Posted by microgyros View Post
Adam,whether your own project is for commercial sale or for your own use is not an issue for me and I am not offering any comment on that.I entered this thread with a specific point that there IS one already on the market that fits that boat and ones half the size again in existence.

Tom,the circuit is ok up to a point.If you lengthen the power supply wires without soldering a capacitor close to its feed then it will self destruct.
To me it is a building block whatever the supplier says.
@microgyros
So I need a capacitor near the battery, what size capacitor would you recommend?
@subculture Your endorsement speaks volumes about microgyros and I respect your opinion. I wish he would have offered the capacitor suggestion earlier on when I was struggling with smoking ESC, but he did not and aeroengineer1 did. Aeroengineer1 offered to supply me with one he was having fun designing for his own use and to help me get the Aluminaut running. I know his heart in offering to sell it was not to become competition or offend anyone, merely keep cost down for his own use, but it started with him trying to help me.
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Old Jun 09, 2013, 11:32 AM
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Mesa Falcon Fld, Arizona, United States
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Tom,

I am running a 15 or 20uF tantalum cap on mine. For something this small, and the low amperage, I would expect this to be good for 6" of wire length at least, though it has not been tested. The larger speed controllers are running in the 200-800uF range, but they are drawing much higher current and have longer wire requirements. At issue is the self inductance of the power wires that feed the ESC. Twisting the power feed lines helps considerably as well as reducing the current through the wire. The wire length changes the inductance (making it higher for a longer length) at slightly greater than a 1 to 1 ratio. Current has a 1 to 1 ratio on the effect caused by the inductance. This is what I used as a ball park rule for sizing my cap.
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Old Jun 09, 2013, 12:43 PM
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Glasgow
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Tom,that is the cap value addressed and with the same value I would suggest.I did not offer that before in the sure knowledge someone else would. I did not see the actual mishap documented until yesterday.
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Old Jun 10, 2013, 02:50 AM
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Thank you to both of you!
I think I understood 72% of what was said, but with that knowledge I am dangerous! LOL
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Old Jun 15, 2013, 04:32 PM
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Grafton, Ohio
Joined Sep 2003
760 Posts
Im not quite sure if you have acheived a viable and marketable product yet...the chinese above kind of threw me! I want a Mini esc that doesnt exceed 1" by 1" and doesnt exceed more than a 1/2" in depth. I want proportional forward and reverse. I would like to have a low voltage cut off but it isnt completely necessary. I want this for 20 US dollars each or less. If you can provide, ill buy 10 to start with, with more later. believe it or not, their for model trains!!
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Old Jun 15, 2013, 05:12 PM
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Mesa Falcon Fld, Arizona, United States
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Ohio Mike,

This is going to fit the bill. It is smaller in each dimension than what you have listed by quite a bit. I was up till about 4AM working on it last night. I am trying to get the low voltage detection working. I will keep you updated.
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