Use PWM to control your Jebao DCT pump using brushless motor controller from ebay

karimwassef · Jun 27, 2016

Ok. I got the 2" version. I'll need to get my arduino to count pulses. The flow of the 1" is too low. The max for the 2" is 2700gph and that's close to what the DCT15000 runs at

karimwassef · Jun 27, 2016

d0ughb0y said:
I take it this does not have any metal part in contact with water right? This would be a nice addition to a controller.

Yup!! Going to experiment. I'm thinking this is key for critical loops like main circulation and then maybe to capture flow in test setups (like testing my surge!).

stage3-s4 · Jun 27, 2016

karimwassef said:
Ok. I got the 2" version. I'll need to get my arduino to count pulses. The flow of the 1" is too low. The max for the 2" is 2700gph and that's close to what the DCT15000 runs at

Yea I figured the 1" may not flow enough. I'm never going to need more than 900GPH on my 40 gallon tank so the 1" was fine. This thing will deff have a pretty significant pressure drop though. It seems very restrictive.

They also make a digital display if you just want to use it to read flow rates directly without a controller.

d0ughb0y · Jun 27, 2016

I can see why the flow can be restrictive.
I found this picture of what the inside looks like. Looks like it has a metal shaft.

At higher flow rate, it might be negligible, but I imagine this will be another thing you have to take out and clean periodically. I don't know if it is feasible to use this permanently installed. Maybe it is, only time will tell.

I just cleaned my return pump yesterday (so I can figure how to replace the ehiem pump with the jebao pump) and the valve above the union is completely stuck, and when I put my finger to see why, it feels like a lot of calcium build up. So the flow meter might get that as well over time, and may need to be removed for a vinegar bath. If you are able to read the flow, then you will probably know when its time to clean it. And you are right the stainless steel shaft should be fine. The MJ pumps have been used in saltwater for a long time and these have steel shafts. I think my MJ pump has been in saltwater for over 5 years now.

karimwassef · Jun 27, 2016

Looks like a typical powerhead cleaning job. They all have SS shafts. Just need two unions and a standby fitting that's the same length during maintenance

I may not put it on my main flow, but on the aux I keep in place in case the two primary pumps fail.

I have three DCT15000s. I prefer to buy cheap and add in redundancy. So, even if one pump fails while I'm traveling, the likelihood of all flow stopping is minimal. Same with pH probes, surge loop actuators, etc...

I still have a few single points of failure but I'm slowly adding massive redundancy where I can.

Still haven't figured out how to do that with my Apex. I have two of them, but I have to physically disconnect and reconnect the other in case of failure... Redundancy is the only path to cost effective quality and uptime IMO

but that's probably an aside for your other thread.

karimwassef · Jun 27, 2016

So .. Last check: is this correct?

<a href="http://s1062.photobucket.com/user/karimwassef/media/0_zpsrjd6cvue.png.html" target="_blank"><img src="http://i1062.photobucket.com/albums/t496/karimwassef/0_zpsrjd6cvue.png" border="0" alt=" photo 0_zpsrjd6cvue.png"/></a>

d0ughb0y · Jun 27, 2016

yes that is correct.
you are quite handy with making all those illustrations.

right. I agree. I just edited my post.
also agree that this would be similar to what apex is offering at a fraction of the cost.

btw, I calculated the RC time constant based on specs of the mosfet, 3400pf and 510ohm, is about 1.8us and will work with freq up to 90 khz. The motor controller chip pwm is 20khz. I have to look at the signal in an oscilloscope to see if the capacitance is really affecting the output voltage or not. Most schematics for this version of driver I found use 10ohms resistor and mosfet with 1300pf input capacitance, so the RC time constant difference is quite significant.

stage3-s4 · Jun 27, 2016

I'm going to try running this flow meter on my main return of pump of my tank. If it ends up getting clogged up and not function in a 1 year or 2 I can just replace it for $10.

I'm curious to see any upgrades you will have for the green motor board. Hopefully something easy will turn up.

d0ughb0y · Jun 27, 2016

If I can figure out how to use the signal pin to get the RPM info out of it, it can be another way of measuring flow. the flow should be directly proportional to the rpm. this will eliminate the need for a mechanical flow meter.

Karim, can you post front and back picture of the stock controller board? I want to see if they use TO-220 or the smaller TO-252 mosfets like the stock 50watt controller.

stage3-s4 · Jun 27, 2016

d0ughb0y said:
If I can figure out how to use the signal pin to get the RPM info out of it, it can be another way of measuring flow. the flow should be directly proportional to the rpm. this will eliminate the need for a mechanical flow meter.

Karim, can you post front and back picture of the stock controller board? I want to see if they use TO-220 or the smaller TO-252 mosfets like the stock 50watt controller.

I would be for that as well. You would obviously have to calibrate the signal to amount of flow which may be easier said than done.

d0ughb0y · Jun 27, 2016

this is the commutation signal from stock jebao controller at the lowest setting (70% duty cycle)

6 commutation = 1 revolution and takes 80.56ms. So that's 60000/80.56=745 rpm
I got to say, the signal from stock jebao controller board is clean as a whistle. The one from ebay board looks like completely random signal. This is one reason I am still considering building a controller from scratch.

stage3-s4 · Jun 27, 2016

d0ughb0y said:
this is the commutation signal from stock jebao controller at the lowest setting (70% duty cycle)

6 commutation = 1 revolution and takes 80.56ms. So that's 60000/80.56=745 rpm
I got to say, the signal from stock jebao controller board is clean as a whistle. The one from ebay board looks like completely random signal. This is one reason I am still considering building a controller from scratch.

Do you have a screenshot of the ebay controller?

d0ughb0y · Jun 27, 2016

I did not save the data for the ebay controller. for the stock controller, I soldered the test points, so I got a clean reading.

I got lazy on the ebay board and just used crappy ic test clips and the signals were not as clean. I have to solder wires to the test point and capture the data again.

karimwassef · Jun 27, 2016

d0ughb0y said:
If I can figure out how to use the signal pin to get the RPM info out of it, it can be another way of measuring flow. the flow should be directly proportional to the rpm. this will eliminate the need for a mechanical flow meter.

Now that is an EXCELLENT idea.

d0ughb0y said:
Karim, can you post front and back picture of the stock controller board? I want to see if they use TO-220 or the smaller TO-252 mosfets like the stock 50watt controller.

ok. I really didn't want to open it, but for science and the common good.. I will.

karimwassef · Jun 27, 2016

stage3-s4 said:
I would be for that as well. You would obviously have to calibrate the signal to amount of flow which may be easier said than done.

Actually, the flow meter you found would make it easy to calibrate the pumps..

karimwassef · Jun 27, 2016

d0ughb0y said:
I did not save the data for the ebay controller. for the stock controller, I soldered the test points, so I got a clean reading.

I got lazy on the ebay board and just used crappy ic test clips and the signals were not as clean. I have to solder wires to the test point and capture the data again.

yes. the connections can make a big difference.

stage3-s4 · Jun 27, 2016

karimwassef said:
Actually, the flow meter you found would make it easy to calibrate the pumps..

Oh yea true. I guess you could use it just for that and then remove it once its calibrated.

karimwassef · Jun 27, 2016

karimwassef · Jun 27, 2016

Looks like DPAK TO-252

karimwassef · Jun 28, 2016

Opening up the stock controller, I can't help but think it would be easy to hack and use an arduino to signal up and down and then take the gate signal off one of the FETs to create a counter of cycles (~flow counter).

Use PWM to control your Jebao DCT pump using brushless motor controller from ebay

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