Help with Water Pump

As usual, I take a breather for a few hours and you guys fill the forum with more posts!

@ronv
Nice summary of where we're at.

Current limited FET switch. No current limit on initial start up.

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As ()blivion pointed out, there is instantaneous current-limiting in the later versions of my PDM design, which is effective at all times, including start-up. If the limit is exceeded for the trip time then the driver switches off....then retries later.

it may be easier to use some of the existing circuitry for the second controller

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I think we've established that the existing circuitry needs beefing up. Once we've got a workable driver then that would be applicable to both the wave controller and tide controller.
It would have been nice to 'dial in' the output voltage in the OEM controller to use as it as a test supply for a pump, but if the controller is likely to self-destruct ......?

@KISS
Shame about the OEM controller death. Wonder what caused that? What was the load?

Edit: To save finger-strain, can I suggest we refer to the OEM controller as 'OEMC' ?

So Close

alec_t;1068416[quote said:

As ()blivion pointed out, there is instantaneous current-limiting in the later versions of my PDM design, which is effective at all times, including start-up. If the limit is exceeded for the trip time then the driver switches off....then retries later.

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Right you are. I updated it. So that only leaves auto retry as an obstical to that one since Joe said adjustment is not critical. Joe, what do you think about a reset button instad of automatic retry of a stalled pump?

Also on the second set of pumps: Is this one off and one on 24/7? Full power as well?

Don't let me talk you into something you don't like. All the features can be met it just gets a little more complicated.

For example I could see where the pumps on high all the time might make the waves to high.

It would have been nice to 'dial in' the output voltage in the OEM controller to use as it as a test supply for a pump, but if the controller is likely to self-destruct ......?

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It would be really nice to have this data point for any of the options. Joe, could you do it if Kiss gave you instructions?

KeepItSimpleStupid said:

Here is a really interesting paper: https://www.advancedaquarist.com/2011/7/aafeature?gclid=CM2cmO-J9bACFVITNAodXXdt-Q

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Thanks, I had not seen that. Sanjay Joshi is a living legend in the world of reefing.

()blivion said:

Should be. Just don't run or start the vehicle while your doing it. You may want to disconnect one cable too while your at it. But if your careful it shouldn't matter.

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The pump took off right away when hooked to my 12V truck battery.
My next door neighbor has a riding mower. Do you want me to see if it has a 6V battery and if so, hook the pump to it?

Here's a picture of the tank. It is a super heavy duty plywood box that is coated with poured epoxy. It's been full of tap water for the last couple months. There are a couple sticks stuck in coffee cans with concrete. I'll tie strings to the sticks to see how different pump placement affects water movement. DIY is so much fun. Thanks for helping me DIY electronics, but here you guys are the DIYers, I'm just following. Having a lot of fun while I'm at it. This is crazy amazing incredible stuff. Thanks so much.

So that only leaves auto retry as an obstical to that one since Joe said adjustment is not critical.

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I thought auto retry was preferred over manual reset and speed adjustment wasn't critical

Do you want me to see if it has a 6V battery and if so, hook the pump to it?

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That would be useful. My betting is that the pump will start ok on 6V, but slightly slower. Get your stop-watch on it, Joe. Oh, and don't flood his mower .

alec_t said:

I thought auto retry was preferred over manual reset and speed adjustment wasn't critical

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Auto re-try is definitely preferred.

The ability to slow down the pumps for feeding would be nice, not critical.

I'll see if the mower is 6V and fire up my cell phone stopwatch.

The mower is 12V. But I'll see if my other neighbor still has their electric toy car that runs on 6V.

OEMC back from the dead

Which means, the probable failure was due to a CMOS hiccup due to a spike or a regulator glitch or evan a logic glitch. Those will recover with time or with little help. In some cases an item can "break and then leave the batteries out for 6 months and it will suddenly work again.

The weird part was that the regulators were not warm and there was no load and my supply was definitely in current limit (3A max). I also didn't scope anything or look for a frequency at the switching regulator.

With an unregulated 24 VAC supply, it does put the controller at risk without some sort of TVS (Transient Voltage Protection) at the input. I wasn't using one, but it does suggest an issue with the OEMC. Transients.

When I did apply power, I typically broke the power connections rather than let the supply come up on it's own, but I did do both. This sort of reminds me of a microprocessor based system I was building with a single board computer. It worked just fine using a switching power supply, but failed miserably on a linear supply. The processor reset didn't have an good edge. I was able to change a part to the schmidt trigger version and all was well. The parts were socketed.

24 * √2 = 33.9 V. This is close to the max limit of 35 V of the 7805 and close to the 40 V limit of the 2576 of 40 Volts.

The "general fix" is to short the power supply pins with nothing connected. I've recovered a few things this way. It is a documented phenomena, but I didn't try it.

I had a clock that died in my car during a jump and the dealer wanted $350 for a new clock. Fixed using the method above. A guy had a bike compute that he drug across a rug in his van. Fixed using the method above. Another guy had an HP calculator that was using "commas" for a "decimal point". Fixed in the same way.

Tentatively, the OEMC comes up at the lower voltage providing the power supply caps have discharged completely. A short glitch will make it continue where it left off.

@Joe

MMMM! With extra pumps and an alarm, try this on for size.

With the 4 pump system, just knock off the one that fails an have an alarm. Assume that two pumps don;t fail unless the tank springs a big leak. At least there is water movement.

With the dual pump system, if a pump fails sound an alarm and use the other pump. Ignore the two pumps that operate at the same time failure mode.

rationale:
The pumps could be fragile and would be stressed the most everytime it starts. The most likely cause of a pump not starting would be that it needs cleaning.

Alarms need to be heard until silenced. Then an indicator is needed.

It might be advisable to provide a dry contact closure for an alarm condition. The future purpose would be an automation system that might respond to that. A use could be say a wireless alarm system that sends a signal to the bedroom.

When an alarm is silenced, you are normally in "trouble mode"

More sophistication, which we are trying to avoid could provide a generic alarm, a trouble alarm and "pump failure tide" and "pump failure wave", "Power fail wave", "Power fail tide"

Later, when Joe has some extra cash, systems are available that send cell phone TXT messages. You rarely have exta cash with a hobby.

Again, they don't have to be implemented now, just have the ability in the future. If all it takes is to have a connector taht would go to a sophisticated "alarm module", that's cheap. You may have a simple module now and a more sophisticated one later.

My vote is to not pump retry, but a variation

My vote is to "not retry to restart the pump", but to disable it in a way that water movement still happens for the likely reason for rotor lock is needing cleaning and restarting is a potentially damaging time for the pump. If it tried only few times (even once) to restart, that would be better, but more complicated.

Something we never discussed, but the "HOOKS" may be there already. Monitoring the voltage across the FET sense resistor is an indication of current and it also an indication of "torque" which means it's an indication of how much friction the motor is seeing. It could be part of a regular PM or just like vibration testing is used for preventative maintenance, this could be used too. Bringing the test points out to a simple rotary switch and banana jacks is a simple way. Adding a <$20 meter and power supply from ebay is a way of making it nicer. Just setting the meter to read 100% when they are new at the operating condition would be OK. Then, once in a while the meter could be rotated via the selector switch to look at the operating pumps. Further sophistication might have an LED that's illuminated next to the positions with operating pumps.

I know that the focus is to get a pump module to work and efforts for the sillyness need to be abandoned for the most part, but if it's easy go for it.

Easy could be: Make sure there is room for a connector that goes across the sense resistor. Make sure there is room for a LED driver for the operating pump. You don't have to implement anything. Just anticipate.

Alarms, the same way: Just anticipate.

In some cases an item can "break and then leave the batteries out for 6 months and it will suddenly work again.

The "general fix" is to short the power supply pins with nothing connected. I've recovered a few things this way. It is a documented phenomena, but I didn't try it.

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I'm sure I don't need to tell you this. But sometimes when you trip a safety or something similar happens in a device, the quiescent current can be low enough to remain powered for up to several minutes by the devices filter capacitors alone. There are also other times that this can happen. For example, anything with RAM can exhibit this phenomena. This whole problem is why most reset procedures say unplug your device for >30 seconds. I have seen all sorts of stubborn behavior with devices because of this (My WRT54G for example). If it happens to you again, you can try to short the power supply pins like you said. However, sometimes shorting the power supply pins isn't enough because there are rectifying diodes before the capacitors. Such as in common wall adapter powered devices and our OEM pump controller. With this in mind you may have to short the capacitor directly. But then again, this may not be happening at all.

ob() said:

This whole problem is why most reset procedures say unplug your device for >30 seconds. I have seen all sorts of stubborn behavior with devices because of this

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Proper reset generators are expensive. Transient protection is expensive. That's the only reason. I once had a major scientific manufacturer of a Multichannel Analyizer (A device that puts voltage pulses in bins and counts them) The Y axis is counts and the x-axis is bins. The X-axis in this case was keV or thousands of electron volts.

One of their board kept blowing up at $1200 dollars to repair. Fortunately, they did supply a schematic and there was absolutely nothing at the input side. This was their lowest end analyzer and we were essentially building our own EDS unit or (Energy Dispersive X-ray Analyzer) (. https://en.wikipedia.org/wiki/Energy-dispersive_X-ray_spectroscopy). The SEM (scanning Electron Microscope) was probably from the 70's at the time and was made from a bunch of 741 OP-amps. Later we got a real SEM and a real EDAX with service agreements and fancy software. But at the time, we were interested in the % composition of three elements. We did use an EDAX detector and low-noise amplifier.

Anyway, the MCA company told us that it wasn't covered because the instrument requires 120 V 60 Hz and obviously we were not supplying that. A $100 surge suppressor, with a connected equipment warranty, solved that problem.

FET Power

Actually we never got all the way down once I started looking at the correct FET.

Check my numbers, but it looks okay. Toasty, but okay.

Probably a good idea to keep the motor voltage high enough to fully turn on the pump FETS.

@Joe

In that one mode, would slowing the pumps be equivalent to bursts. I don't think so, but I thought i would ask. I'm not talking about the "flicks".

Slowing the pumps down for 5-10 minutes at feeding time lets a smaller percentage of food get swept passed the surface overflow into the filter. So just a slowdown. If it's not easy, I say forget it. It's not critical.

No luck on the toy car battery, but I called a guy who rebuilds antique tractors with 6V batteries and he told me to bring the pump to his place. He can only see me evenings and this is a crazy busy week. I'm shooting for Tue.

In post #778 you said

Joe said:

One for tidal simulation that would control two opposing pairs of pumps (4 pumps). One pair would run 6 hr and be able to be adjusted for about 30 sec on, 5 sec off.

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Burst mode here would not be the same as changing the speed, right?

Right, they would still run 30 sec on, 5 sec off but at a slower speed for lesser volume at feeding time.

@Joe
Do you own a stupid timer such as this one: **broken link removed** ?

The tripper can be set for 15 min on/ 15 min off and thus can EXERCISE the pump module.

You would also need a relay with an AC coil that would plug into the timer.

That would give you a chance to initially concentrate on a pump module. But, You also have the controller that worked properly too. The long interval timer with a sub-interval timer and flick.

The timer could exercise a pump(s) ON/OFF at 15 minute intervals.

The controller is almost looking like micro material with a rotary encoder and an LCD or something, but the pump modules have to work!

ob(): Do you want to go off in one of the microprocessor forum and design a micro based controller with Joe's permission.

Maybe do some selection of parts, pseudocode, cost estimation etc. But no real code. Just Brainstorming.

BTW, I have a Superpro and two ARMEXPRESS development kits from here: https://www.coridiumcorp.com/Products.php I just have to start playing. The virtual world is easy. I also have a PICAXE in pieces. e.g. never tried building or connecting to it. Wanted to get my feet wet. The SuperPro is shipping a floating point Basic now and I upgraded my firmware to support it.

Disable program - turn OEMC into ~10 Volt supply

@Joe

Let's see what you can do with the Solder wick. All you have to do is unsolder two connections and lift those leads.

Connect your 24 VDC supply using any polarity to the 24 VAC input.

You can probe the jack, but alternately:

The (-) of the DC-OUT Jack is the same as the (-) of your 24 VDC supply.
(+) DC-OUT is also available at the band side of the BIG DIODE near the fuse.

The two other resistors that I have shown may need to be changed if we change to a variable supply. Somewhere in this thread is the post size and calculations.

But, a 10 Volt supply that doesn't vary is a start.

You might also pick up a solder sucker and an extra tip from Radio Shack. https://www.radioshack.com/product/index.jsp?productId=2062745 The performance of these things is always poor, but they do work. Clean it after every desoldering session. When the tips wear it will no longer work, the plunger will stick out of the tip, so it always makes sense to have a spare.

I'm shooting for Tue.

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My company already did 9 shows on Saterday with 9 more to come on the 4th.
I havent seen my laptop in days.
Have fun and be safe.
See ya after the 4th.