Synopsis:
Frugal Salty Joe (SJ) is building a salt water reef tank with live Coral. He built the tank too into a wall in his house.
SJ bought some 24 VDC pumps (underwater propellers, basically) off of ebay that ran off a 240 VAC to 24 VAC wall wart.
He wants to use the 24 VDC pumps to "make waves" and "simulate a tide"
SJ enlisted ETO for some help building a controller.
Initially, the problem seemed simple. A little CMOS Voodoo and a FET switch for 2 pumps at a time and your done.
alec_t bit the bullet and designed version 1 of the tide controller.
This is basically two pump pairs that run for an extended period of time and then switch. The pumps that are off, "flick" or turn on briefly so the fish won't get blown away when they turn on full force.
SJ built the controller and it worked for a few days to a week or so and one motor motor catastrophically died.
SJ dissected the motor (hammer) and sent it to me for some other analysis. The motor was powered by a 24 VDC, 6-10 amp supply with no protection, not even a fuse per pump. So, it let out the "magic smoke". There may have been fuse(s), but I think it didn't blow.
So, we found that it was a brushless DC motor and the failure mode is somewhat unknown, but one coil was shorted and solder melted where it should not have melted.
I think it uses a Melexis Hall IC and P-channel FET, and that the operation might be specified for 18 V max, but the application note says 5V to 24 VDC is permissible.. I found the inductance and resistance of the coils which allowed a better simulation. The OEMC, or OEM controller doesn't run the pumps for very long at full speed and the OEMC has some current limiting because it uses a Switchmode regulator with Imax of 3A and a peak current of 5A.
So, alec_t worked on another design with help, primarily critiques, from the peanut gallery ronv, me, and ()oblivion which requires a separate motor controller with protection for each motor.
There is a need for a FEED MODE" which slows the pumps for 15 minutes, so the discussion has a brief interlude trying to come up mechanisms for doing the feed mode. From modifying the OEMC, to a different switchmode regulator and finally alec_t's simulated and physically made design that is now an article at ETO.
Initially, the idea is to use four modified OEMC's to provide 18 VDC for the next test. I guess, we are not sure yet, if Alex's new control mode will be used for the upcoming test or not.
So, SJ went on vacation and came back and is procuring parts as we speak, so SJ can try again to see if the pumps can survive.
SJ has been asking good questions and he's not an electronics hobbyist, but does know which end of the soldering iron is hot and seems to be doing a great job.
So, we will be waiting for SJ to build a controller.
Don't know if it ill be with modified OEMC's or alec's new controller mode that reduces the average current applied to the motor, bit we are in agreement that the lowest voltage, probably 18 VDC or less is preferred.
So, we basically sit in "Hurry up and wait mode" until SJ builds something and can put it to the test.
If it doesn't work, we do have a "Plan B" which none of us like which would require replacing epoxied electronics in the motor.
The "tide sequencer" worked in terms of turning off and on the motors properly, but the motors didn't survive. There still is the design of a "wave maker" to deal with and a "feed mode" timer. Trivial in comparison as to what's been going on.
The thread is still on topic "Help with water pump"
Guys: make any corrections you may see fit. I wasn't participating in this thread in the beginning, but I then saw some struggling, so I offered help.
PS: This thread, I think, inspired me to look at aquarium filtering solutions for laundry lint. The device I chose was extremely effective, but I need to do some major plumbing to move it toward the back of the laundry sink instead of the front. On another related note, I manged to create an extremely usable silt filter for a residential drainage system that captures 99% of the silt by weight. At present, the working prototype has no bypass, but one can be added. Incremental cost without the bypass, $10, without shipping of parts. The prototype, about $80. I had to buy 500 thingys to get 3 and had to buy 5' to get 1.5" of the stuff.
Frugal Salty Joe (SJ) is building a salt water reef tank with live Coral. He built the tank too into a wall in his house.
SJ bought some 24 VDC pumps (underwater propellers, basically) off of ebay that ran off a 240 VAC to 24 VAC wall wart.
He wants to use the 24 VDC pumps to "make waves" and "simulate a tide"
SJ enlisted ETO for some help building a controller.
Initially, the problem seemed simple. A little CMOS Voodoo and a FET switch for 2 pumps at a time and your done.
alec_t bit the bullet and designed version 1 of the tide controller.
This is basically two pump pairs that run for an extended period of time and then switch. The pumps that are off, "flick" or turn on briefly so the fish won't get blown away when they turn on full force.
SJ built the controller and it worked for a few days to a week or so and one motor motor catastrophically died.
SJ dissected the motor (hammer) and sent it to me for some other analysis. The motor was powered by a 24 VDC, 6-10 amp supply with no protection, not even a fuse per pump. So, it let out the "magic smoke". There may have been fuse(s), but I think it didn't blow.
So, we found that it was a brushless DC motor and the failure mode is somewhat unknown, but one coil was shorted and solder melted where it should not have melted.
I think it uses a Melexis Hall IC and P-channel FET, and that the operation might be specified for 18 V max, but the application note says 5V to 24 VDC is permissible.. I found the inductance and resistance of the coils which allowed a better simulation. The OEMC, or OEM controller doesn't run the pumps for very long at full speed and the OEMC has some current limiting because it uses a Switchmode regulator with Imax of 3A and a peak current of 5A.
So, alec_t worked on another design with help, primarily critiques, from the peanut gallery ronv, me, and ()oblivion which requires a separate motor controller with protection for each motor.
There is a need for a FEED MODE" which slows the pumps for 15 minutes, so the discussion has a brief interlude trying to come up mechanisms for doing the feed mode. From modifying the OEMC, to a different switchmode regulator and finally alec_t's simulated and physically made design that is now an article at ETO.
Initially, the idea is to use four modified OEMC's to provide 18 VDC for the next test. I guess, we are not sure yet, if Alex's new control mode will be used for the upcoming test or not.
So, SJ went on vacation and came back and is procuring parts as we speak, so SJ can try again to see if the pumps can survive.
SJ has been asking good questions and he's not an electronics hobbyist, but does know which end of the soldering iron is hot and seems to be doing a great job.
So, we will be waiting for SJ to build a controller.
Don't know if it ill be with modified OEMC's or alec's new controller mode that reduces the average current applied to the motor, bit we are in agreement that the lowest voltage, probably 18 VDC or less is preferred.
So, we basically sit in "Hurry up and wait mode" until SJ builds something and can put it to the test.
If it doesn't work, we do have a "Plan B" which none of us like which would require replacing epoxied electronics in the motor.
The "tide sequencer" worked in terms of turning off and on the motors properly, but the motors didn't survive. There still is the design of a "wave maker" to deal with and a "feed mode" timer. Trivial in comparison as to what's been going on.
The thread is still on topic "Help with water pump"
Guys: make any corrections you may see fit. I wasn't participating in this thread in the beginning, but I then saw some struggling, so I offered help.
PS: This thread, I think, inspired me to look at aquarium filtering solutions for laundry lint. The device I chose was extremely effective, but I need to do some major plumbing to move it toward the back of the laundry sink instead of the front. On another related note, I manged to create an extremely usable silt filter for a residential drainage system that captures 99% of the silt by weight. At present, the working prototype has no bypass, but one can be added. Incremental cost without the bypass, $10, without shipping of parts. The prototype, about $80. I had to buy 500 thingys to get 3 and had to buy 5' to get 1.5" of the stuff.
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