Help with Water Pump

[4pyros]

Try doing this in the 80's. Assume everyone had a FAX machine and lead for their pencils.

You would have to know someone in town to help and it would take a lot longer.
There would be more serious failures but that might be fun.
Talk about smelling the smoke.

 

[KeepItSimpleStupid]

Would the current increase enough without the rotor to trip the alarm?

Short circuit current would basically be the same. Some part of the coil would become an air inductor with the removal of the armature. Under that condition, the magnets would not be energizing a coil, but there is probably a spot on a 2 pole rotor where the motor would not rotate anyway and the IC might have to give it a little push, but the output is complementary. So, maybe my theory has a hole in it? If the hall effect sensor does not detect a magnet and the output is complementary, is one of the coils on? Or is it 1 sec on, 5 sec off? That's what happens when you sleep on things.

 

[alec_t]

Earlier, I suggested to just remove the armature. It's the equivalent of a stall and you won't get hurt or break anything when trying to force something that wants to rotate stopped.

I like the word 'just' . I thought the pumps were sealed units? Is removal straightforward?

Would the current increase enough without the rotor to trip the alarm?

I don't see why not. Coil inductance would be lower and the Hall IC would be stuck in one of its two toggle states, so only one coil would be driven.

Talk about smelling the smoke.

Please, no smoke!

 

[KeepItSimpleStupid]

I like the word 'just' . I thought the pumps were sealed units? Is removal straightforward?

Your right, I can't answer that since I did not get an armature to play with. Electrically, it has to be sealed. It also has to have a rotating shaft seal.

Yelling JOE!!

 

[salty joe]

Thanks for the final tests Alec. With a locked rotor, the alarm kicked in immediately-I did not even get the chance to count to one. I removed the pencils from the pump while the alarm was screaming, let the alarm finish screaming and then the pump took off like nothing ever happened. I was already done by the time I saw the remove the rotor option. Nothing was damaged. All pumps toggled along quite nicely.
KISS, we did talk about hooking up the trimmers when I had them wrong. They are good now. It's just that when the knob is pegged, there is a problem. Move the knob a tiny bit and it's fine. BTW, I took your advice and was consistent with the trimmers so that turning them clockwise increases resistance on all trimmers.
Sure am glad I put a copy of speed control in my documents. I’m pretty sure I have all the schematics saved. Speed control now. This is gonna be cool. Thanks you guys-you’re the best!
I hope every one of you guys has a Merry Christmas. And a happy, healthy New Year too!

Hey-I hear something... It would've benn super easy to remove the rotor... easier that sticking in 5 pencils? Jamming a pump is pretty easy stuff.

 

[KeepItSimpleStupid]

ArrrrrrrWssssssB
..........W*****B

In the above example the pins are A, Wiper and B. The resistance is the "rrrrrrrr". The other en would have a resistance of "ssssss". The "******" indicate that "ssssss" is shorted. So, if the Wiper is all the way to the right and the wiper lifts, you get the full value of the pot and not an open.

So, you have another tiny mod to do.

I do suspect that you will have to clean the rotor every so often and the voltage across the sense resistor will go up depending on the shaft friction.

Yippee!

Since this is now the 21st Century and we all have our Makerbots, we can send gifts over the "wire", right? The wave of the future.

 

[alec_t]

With a locked rotor, the alarm kicked in immediately

Good news. With the trimmer only a tad past minimum I did wonder whether it would be the trip or the Hall IC which kicked in first. Now we know.

Sure am glad I put a copy of speed control in my documents. I’m pretty sure I have all the schematics saved.

If anything's missing let me know and I can PM them to you.

ArrrrrrrWssssssB
..........W*****B

I thought that was KISS cussing at something, but I see now it's ASCII art

Merry Xmas all!

 

[salty joe]

The tide control has a 7812 voltage regulator. Will that one source of 12V feed the speed control modules, wave controllers, alarm module-in other words should I connect all 12V wires in all modules to the 12V source at the tide controller? The 7812 v reg is mounted to a heat sink.

 

[KeepItSimpleStupid]

The 7812 is good for an AMP, but the dissipation depends on the voltage difference. e.g. P = (20-12)/1Amp and that's like 8 Watts. So, pretend your holding an 8W nite light in your hand at full capability.

The amount of 12V is very miniscule and the most current you will be drawing will occur in alarm. Distributed regulation is good because the amount of heat is less in one spot. Less heat means more reliable.

For now, I think I would use a single 7812, but wire some invisible components so you can distribute the power a bit. The alarm module is quite independent, and that could be a logical break. An "invisible" component is one that you might add later.

Another possible, preferable and makes the most sense, is to have one 12 V regulator for each 20 V supply.

 

[()blivion]

~79 hours left till the one year anniversary of this thread. (And one week till the anniversary of the day I joined it.)

Late merry x-mas every one.

 

[4pyros]

What a hole year. Wow

 

[4pyros]

Another possible, preferable and makes the most sense, is to have one 12 V regulator for each 20 V supply.

Yes you will want to keep it some what modular.
Would it make sense to put the 12 volt reg on the same board as the alarm?

 

[salty joe]

Thanks guys. I will have eight pumps running and was planning on using two power supplies. IDK, but thought a single v reg might get overloaded. Did not realize the alarm would be a major consumer of 12v. Makes sense. Anyway, don't want two 7812s to get into conflict. Thanks Alec for pointing that possibility out.
Do you think one power supply and one v reg per four pumps is the way to go? Just trying to get a feel for the final layout.
I have a good start on the speed module, in a couple days I'll get a chance to get back after it.

 

[alec_t]

Do you think one power supply and one v reg per four pumps is the way to go?

Remind us what the ratings of the two '24V' power supplies are. Can't remember; do they have inbuilt current-limiting or fuses? Two pumps starting simultaneously would draw ~9A briefly.
BTW, since the power supplies are mission-critical, do you plan to have a backup?

a single v reg might get overloaded

No chance. As KISS says, the max 12V load is likely the alarm buzzer, the rest of the circuits/modules would only draw tens of mA in total. I would guess the alarm needs 100mA max (check its spec), unless you're planning to wake the neighbours.

 

[DerStrom8]

Wow, this is impressive. Probably the ONLY time I've ever seen a thread last an entire year and STILL stay on-topic!

 

[salty joe]

When I get home tomorrow evening, I'll check out power supply specs.
A backup would be nice. Any chance of rigging something up with a car battery after we get the water moving about?
Can't remember what the alarm draws, but it's not much. Will double check. So it sounds like just one v reg for the entire rig. Thanks all.
KISS I'm on an IPad and my fat fingers hit your - when I tried to hit your +. You get nothing but +from me. Sorry and thanks.+++++++

 

[DerStrom8]

When I get home tomorrow evening, I'll check out power supply specs.
A backup would be nice. Any chance of rigging something up with a car battery after we get the water moving about?
Can't remember what the alarm draws, but it's not much. Will double check. So it sounds like just one v reg for the entire rig. Thanks all.
KISS I'm on an IPad and my fat fingers hit your - when I tried to hit your +. You get nothing but +from me. Sorry and thanks.+++++++

KISS or me?

Hahaha, no worries, anyway

 

[salty joe]

Did not know I clobbered you to. Please add no glasses to fat fingers and little screen.

 

[KeepItSimpleStupid]

The one issue you want to avoid is an input to the CMOS IC's being driven when there is no power. The IC's can usually be driven a few mA max in that condition. I've never looked at everything pieced together.

Other than the aspect of modularity and two supplies, there isn't much to consider. The LEDs and the sounders are your big current hogs and here 20 mA is big and 100 mA is huge.

 

[KeepItSimpleStupid]

Shoo! Shoo! Get that car battery out of your head. After a couple of deep discharges, the battery will be useless. A car battery has plates that are very close together and as a result it has a High Cranking Amp capacity or a low series resistance. It also means that supherization or when sulpher precipitates out of the battery acid, it shorts the plates together. Result, dead irrecoverable battery or commonly known as scrap.

A "deep discharge" battery cannot provide high cranking amps because the plates are further apart.

Long term outages - think propane or natural gas auto-start generator. Short term, think UPS.

You do have about 6 motors at 1 amps at 20 V, That's 180 watts. Not so fast. They need at least 3 A to start, so your UPS has to be able to deliver 3*30*6 or 540 VA for that brief time that they all start. So, my math is wrong, 2 pumps are supposed to be off. This is where VA and Watts differ in their meaning. Staggered starts can prevent this large starting load. I forgot the heater and stuff.

So, do we have a new design issue? The system has to run off of 12V?