Help with Water Pump

[salty joe]

Odd, though, that it's just for one wave pump and not the others.

I thought so too. Especially since it only chirps every few minutes. It reminds me of working with the old pumps when some were 'fussy' until we got everything nailed down. BTW, the old pumps do an excellent job as filter pumps.

Thanks, I'll try to get that new mod done today after work.

 

[salty joe]

That darn pizo still chirps every few minutes for the wave pump even after replacing R3-6 with 300K in the wave FSM. (It also has the mod from post 2279) Maybe chirping a little less often-I never timed it so I'm not sure.

Having an alarm on the eight tide pumps is a huge plus. Thanks for making that work.

 

[alec_t]

Hmm. Can you monitor the Rsense voltage for the fussy wave pump to check what it does before and during that chirp? It would also help to know how it differs from the Rsense voltage of the OK wave pumps.

 

[salty joe]

I held my DMM probes across Isense and power ground terminal points on the fussy pump for 10 long minutes and no chirp. Everytime the pump turned on, for a split second I usually got 0.02-0.03V, a few time as high as 0.12V before jumping to 0.28V. I did not check the other pumps as long, but the initial V was mostly 0.02-0.03V.

The alarm system becomes less and less sensitive to an unplugged pump as the wave pulse in shortened. The fussy pump is the most sensitive, but even it does not trip the alarm when the pumps are cycled at about 1 second. The tank's empty right now so I can't say for sure, but it looks to me like I'll be using the wave at a shorter pulse length than the alarm can pick up.

 

[alec_t]

I held my DMM probes across Isense and power ground terminal points on the fussy pump for 10 long minutes and no chirp.

Murphy strikes again .

Everytime the pump turned on, for a split second I usually got 0.02-0.03V, a few time as high as 0.12V before jumping to 0.28V.

That split second is presumably the time it takes for the new controller to wake up each time it is switched on by the wave controller.
The FSM takes a few seconds before tripping the alarm for an unplugged pump, so cycling the pumps at ~1 sec should prevent the alarm tripping.

 

[salty joe]

I'm pretty surprised to need such a short wave pump cycle on such a big tank. It looks like the FSM won't work for the wave pumps due to the short run time. Which explains why there was no alarm with all wave pumps unplugged. My mistake for expecting a much longer wave pump cycle. I appreciate the effort to make the alarm work for the wave pumps, but this looks like an unforseen glitch we'll have to live with.

On the other hand, we have a working alarm for the absolutely critical filter pumps as well as the eight tide pumps. Thanks again for fixing the alarm for the tide system.

The extra new pumps should arrive in a few days. I think we're in really good shape. Thanks!

 

[alec_t]

Yes, the short run time for the wave pumps does make it tricky for the FSM to distinguish between the low current state while the new controller gets going and a persistent lack-of-current state due to an unplugged pump. Each time Vt for a particular channel is switched off (i.e. when its associated pump is off) the FSM channel has to re-initialise.
If you can live with the wave pumps not having the FSM function then ok. If not, it might be possible to modify/re-design an FSM specifically for the wave pumps.

 

[salty joe]

An alarm for the wave pumps would be nice. If you feel up to it, I'd be glad to give it a go. Thanks.

 

[KeepItSimpleStupid]

joe

Are you willing to TRY to place a very small value ceramic capacitor like 0.01 or 0.1 uf across Rsense? Don't hold it if at all possible.

 

[alec_t]

The alarm system becomes less and less sensitive to an unplugged pump as the wave pulse in shortened. The fussy pump is the most sensitive, but even it does not trip the alarm when the pumps are cycled at about 1 second.

Can you confirm if this is
a) Pump on 1 sec, off 1 sec or
b) Pump on 0.5 sec, off 0.5 sec

 

[salty joe]

With the fussy pump unplugged, it will trip the alarm down to about 1/2 sec. The other pumps trip the alam down to just under 2 sec.
I set the wave trimmer just to the point where the alarm would not sound for the other pumps.
Neither ceramic 0.01uf nor 0.1uf across Rsense seemed to affect the trip.

 

[salty joe]

I think I found the problem-there's conductivity between pins of the LM324 where there should be none. (I checked it against a new one)
I probably cooked it. A couple ICs ago, I started to cool the IC down with my wet sponge between joints and made a real effort to get the solder iron on and off real quick. So far, so good.
The wiring checked out from what I could tell.
I guess I'll wire the FSM to a new LM324 on a piggyback board and let the cooked one RIP where it died, just like the last IC I cooked.

I just finished the four PDMs for the extra new tide pumps. Fingers are crossed, toes are crossed and from now on, all my cooking is in the kitchen!

Thanks.

 

[alec_t]

Hope the new LM324 does the trick.

Neither ceramic 0.01uf nor 0.1uf across Rsense seemed to affect the trip.

I'm not sure what KISS had in mind there.
Regarding the FSM for the wave pumps, if the pumps will always be cycled with a period ~1sec then the values of R3-R6 could be reduced to ensure the Fault signal goes high if a pump is unplugged. Since the value is fairly critical it might be better to use trimmers (say 250k) in place of R3-R6. Those resistors could be supplied with either the respective Vt signals or with the +12V.

Fingers are crossed, toes are crossed and from now on, all my cooking is in the kitchen!

I've got mine crossed too.

 

[salty joe]

I don't have any 250K trimmers. Do you think a 100K trimmer with a paralell 150K resistor, or a 500K trimmer would do the trick?

 

[salty joe]

I meant in series

 

[alec_t]

500k would be the better of those two options (but more fiddly to set), since you may find the resistance need to be <100k. The big unknown is the start-up time of the new controller, on top of the start-up time of the pump. Set the trimmer such that the alarm just fails to beep each time the pump starts. The alarm should then chirp each cycle if the pump is unplugged.

 

[frank133]

great thread!

 

[KeepItSimpleStupid]

frank133

How long did it take you to read it? It's definitively the longest and most active.

 

[alec_t]

500k would be the better of those two options

On second thoughts the 150k + 100k series trimmer would be better. If it turns out that the minimum setting of the trimmer is still too high then the 150k can be replaced by a lower value (anything ~ 1k-47k). A snag with the 500k option is that inadvertently setting it to zero could damage the LM324.

Hi Frank. Welcome to the forum.

 

[salty joe]

inadvertently setting it to zero could damage the LM324.

.

Thanks, I'd have definitely set it to the min and max just to see what it did. I need to put my IC killing days behind me and change my ways.

Hi Frank. Welcome to the forum.

+1. These guys are incredibly talented and generous, aren't they?