I am posting this *before* I go down this path in the hopes that other (informed) DIY people can help fine tune my conclusions. I am more of a digital guy, so you old farts that are analog, please correct my limited analog knowledge.
I just recently bought the Gyre and love the flow, but not having the pump controlled by my controller is a really bummer. When you get used to your pumps slowing at night, shutting off at feeding time, or running in a preset pattern, going back to a manual controller just sucks.
I know they are coming out with a Apex compatible controller, but since I use 5V PWM in my DIY system, I would need to build an interface just to be able to use the Apex module when it is available.
This got me to thinking about how the Gyre is operating, and more importantly, how could I replace the current controller with something that I can interface directly to.
I am pretty sure I have figured out it uses a Brushless DC Motor(BLDC). I measured the resistance between the 3 pins of the cable and found that any 2 pins are 4.7 ohms, and if I short 2 pins and measure with the 3rd pin, this is 3.6 ohms. This would mean the coils are 2.35 ohms each and wired in a Wye configuration (as opposed to Delta). Everything appears to line up with it being a Brushless DC Motor.
After googling around a bit and looking at the various Arduino based DIY projects to control BLDC motors, I remembered that I had seen lots of Brushless Electronic Speed Controllers on eBay intended for the hobby RC field. Hmm, and these take a 5V PWM servo input, exactly what I have in my controller. If they would work, they would fit my requirements exactly.
So here is my plan, I am going to try to use a RC ESC to interface the Gyre to my controller. Depending on the model of ESC, they offer both forward and reverse rotation and run sensorless (just what we need for the Gyre). I expect I will have to run at a lower voltage than what the Gyre appears to use currently (24V) as the ESC's are all targeted at voltage ranges provided by battery packs (about 12V). The occasional ESC description on eBay lists the actual voltage range that it supports, but most just list the size of LiPro and/or NiMH cells it supports. I am thinking I might be able to get away with 18V (the highest rated ESC I found listed 22V as its limit).
There is also the question about limiting the current through the coils of the Gyre. All the ESC's support much higher current limits than I expect to need. 20A is the smallest common ones, with a few 10A ones as well.
The hobby ESC's are also normally paired with the outrunner motors that spin FAST (like 210K RPM). Have to see if the onboard microcontroller in them is able to adapt to do low speed control as well. Many of the ESC's are programmable, so you can tailor it to your specific need, I am just not sure if it will be adaptable enough to operate the Gyre.
I have not ordered anything yet, I thought I would bounce this off you guys first before I take the leap. Any feedback from guys with electronic experience, especially RC knowledge would be appreciated.
Dennis
I just recently bought the Gyre and love the flow, but not having the pump controlled by my controller is a really bummer. When you get used to your pumps slowing at night, shutting off at feeding time, or running in a preset pattern, going back to a manual controller just sucks.
I know they are coming out with a Apex compatible controller, but since I use 5V PWM in my DIY system, I would need to build an interface just to be able to use the Apex module when it is available.
This got me to thinking about how the Gyre is operating, and more importantly, how could I replace the current controller with something that I can interface directly to.
I am pretty sure I have figured out it uses a Brushless DC Motor(BLDC). I measured the resistance between the 3 pins of the cable and found that any 2 pins are 4.7 ohms, and if I short 2 pins and measure with the 3rd pin, this is 3.6 ohms. This would mean the coils are 2.35 ohms each and wired in a Wye configuration (as opposed to Delta). Everything appears to line up with it being a Brushless DC Motor.
After googling around a bit and looking at the various Arduino based DIY projects to control BLDC motors, I remembered that I had seen lots of Brushless Electronic Speed Controllers on eBay intended for the hobby RC field. Hmm, and these take a 5V PWM servo input, exactly what I have in my controller. If they would work, they would fit my requirements exactly.
So here is my plan, I am going to try to use a RC ESC to interface the Gyre to my controller. Depending on the model of ESC, they offer both forward and reverse rotation and run sensorless (just what we need for the Gyre). I expect I will have to run at a lower voltage than what the Gyre appears to use currently (24V) as the ESC's are all targeted at voltage ranges provided by battery packs (about 12V). The occasional ESC description on eBay lists the actual voltage range that it supports, but most just list the size of LiPro and/or NiMH cells it supports. I am thinking I might be able to get away with 18V (the highest rated ESC I found listed 22V as its limit).
There is also the question about limiting the current through the coils of the Gyre. All the ESC's support much higher current limits than I expect to need. 20A is the smallest common ones, with a few 10A ones as well.
The hobby ESC's are also normally paired with the outrunner motors that spin FAST (like 210K RPM). Have to see if the onboard microcontroller in them is able to adapt to do low speed control as well. Many of the ESC's are programmable, so you can tailor it to your specific need, I am just not sure if it will be adaptable enough to operate the Gyre.
I have not ordered anything yet, I thought I would bounce this off you guys first before I take the leap. Any feedback from guys with electronic experience, especially RC knowledge would be appreciated.
Dennis
