Help with Water Pump

[salty joe]

The two pumps on speed control for the filter (with battery backup) will have a dedicated 15A power supply.

There will be six pumps in the tank (4 on the tide control and 2 on the wave control). Eventually, 5 pumps are bound to start simultaniously for about a 22.5A draw! Can two 15A PS be used for these six pumps, or do I need a min 18A PS dedicated for the four pumps on tide control?

 

[alec_t]

Eventually, 5 pumps are bound to start simultaneously

By my reckoning the max is 3 (ignoring the filter pumps, which will have their dedicated supply), since only 2 are on at any time for the tide function and only 1 at a time is on for the wave function.

 

[salty joe]

I counted the flick function on tide control.

 

[alec_t]

Ahh. Forgot that. However, that shouldn't be a problem. By my reckoning, statistically it's only ~ once per hour that the 1/2 sec flick for the inactive pump pair is likely to coincide with start-up of the active pump pair. The 15A supply will probably be quite happy with ~18A for 1/2 sec. But if, instead, it shuts down or current-limits for that 1/2 sec then it just means one flick is lost and the start of the active pair is delayed ~1/2 sec....no big deal.

 

[salty joe]

Great, it sounds like the whole system can be run with the two 15A power supplies I have.
I just finished a new PDM with a 470u cap and snubber between the pump leads and a diode added to the LED. With the PDM hooked up to the tidal controller, the LED on the PDM lights up then blinks off and back on at about 5 sec., then at 11 sec. the pumps starts running. I timed it several times and it was consistent.
The first time I hooked it up, I crossed Vt with signal ground. Did I probably fry an IC? Also, the pot on the tidal controller that controls how long the pump is off between toggles is no longer working correctly-the longest off time is only a few seconds.

Edit: I hooked the PDM that is all beat up but working to the the tide controller and the tide controller is OK-what a relief.
Tomorrow, I'll go over every connection on the new PDM and find my mistake. Do you think sending 12V to Vss ruined the IC on the new PDM?

 

[alec_t]

I crossed Vt with signal ground.

Do you mean (a) you touched the two together, or (b) you had them reversed? If 'a', then you probably got away with it. If 'b', then the IC in the PDM would likely have fried.

the longest off time is only a few seconds.

It was designed to be ~5 secs. Are you getting that? Do you want it >5 secs?

 

[salty joe]

I mislabled the terminal points and had the Vt and signal ground reversed. %$#&! Switching out the IC will test my soldering skill.

The pot that controls "off" on the tidal controller gives me anywhere from about 11 sec off down to next to nothing. It's just right.
Thanks.

 

[KeepItSimpleStupid]

I looked at the ckt too and thought that there probably would not be any damage or a wiring error.

Since it never worked look for other signs of damage. Take a look at the voltages at the IC pins. They pretty much should be aproximately at Vcc or signal ground. If they are at Vcc, measure the voltage from Vcc to that pin. I'll worry if the values are EXACTLY zero except for the GND pin on the IC. Wait long enough for the motor to at least start once or twice. Toggles and blips are, of course OK.

Vcc = 12.00
1. 11.9 (0.10)
2. 12.00 (0.00)
3. 300 mV (out a)
4. Blip (100 mv, 11.3 V) or brief Blip
...
7 0 GND
...
14 12.00 (vcc)
I made up pin numbers and I/O

I waited for Alec to respond first.

 

[salty joe]

Just saw your post KISS. Anyway, I managed to switch out the IC and the driver works as planned. But it was sorta brutal-I lost the little copper soldering rings and just soldered the wires to the IC pins. It aint real pretty So I'm still chasing the elusive really nice, almost perfect soldering job. I realized when I started this last build I was getting low on diodes and such so until the parts arrive, hopefully in a few days, I won't be soldering.
It is satisfying to fix something that frustrated the heck out of you, isn’t it? When the parts arrive, I’m gonna get these right. Might even double check the labels I put on the terminal points.
Thanks for all your help guys.

 

[KeepItSimpleStupid]

Gee, I'm surprised you didn't use sockets. Machine pin sockets are expensive, but are extremely reliable. Glad the swap fixed it. Too bad, you didn't try actual troubleshooting.

With that chip the logic levels are so close to Vss and Vdd, but exactly equal would be very difficult to obtain unless shorted. That was the plan, anyway.

 

[alec_t]

Glad you sorted the problem out.

I lost the little copper soldering rings

That's where strip-board has an advantage over dot-matrix board; a strip is unlikely to become detached.

It is satisfying to fix something that frustrated the heck out of you, isn’t it?

Yes, it is. Electronics projects can be frustrating at times (as you've already discovered over the last year or so!), but getting something working as planned is rewarding. It's what keeps us hobbyists going.

 

[salty joe]

KISS, early on, somebody mentioned that a lot of problems arise from the use of sockets. The kind of problems that often show up way later. That's why I solder the ICs.

I got these two PDMs done, but the alarm did not work on one of them. I looked at Q3, but could not see a problem. As I was comparing voltage from one PDM to the other, I found a discrepancy and my problem at R 11. I forgot to run 12V to the R11/cap/diode junction. Thank you Alec for having me check that resistor. Both PDMs work as planned and all voltages are consistent for both PDMs.

Here’s a pic of them. My battery died, so I did not take a shot of the back. It’s pretty much a jumble of wires, but the soldering is not too bad.That little map of the physical component placement for the PDMs is a big help. Six more PDMs to go. Thanks guys.

 

[KeepItSimpleStupid]

Proud of you Joe. They look really nice.

Are the trimmers touchy to adjust?

Sockets can be a curse or a blessing. These sockets https://www.digikey.com/product-detail/en/110-93-316-41-001000/ED3316-ND/14041 are called machine pin sockets. I never had any issues at all with them. As you can see, they are quite pricey. These are also gold dipped. There is never an issue with these.

 

[ronv]

Looks good Joe!

 

[alec_t]

Good work, Joe. Neat.

I did not take a shot of the back. It’s pretty much a jumble of wires

It would be! Just have the fronts on show when you're giving visitors guided tours of the system

 

[salty joe]

Wow, thanks for the kind words.
It's pretty easy to get a fine adjustment with those trimmers , at least for this project.
My friends are blown away when I show them the controllers etc. and I always tell them about my high powered, creative online friends who put this together, I'm just running the soldering iron.
Thanks guys, we're closing in on this-thanks for hanging in there with me.

 

[salty joe]

I built two more PDMs and one works but the other sounds the alarm immediatly. I looked at the trimmer and looked around-I wonder if you guys could maybe take a stab at a good place or two to look before I decide to spend a couple hours going over it with a fine toothed comb and maybe find the problem or cut my losses and pitch it now. The good news is, it's the first PDM on the board. So I built the next PDM on another board. Today, I'll add another PDM to that board.

 

[alec_t]

the other sounds the alarm immediatly

Was that with or without the pump connected?
Check the volts at the trip test switch first. Should be >0 ! Then check at Isense and Q2 collector. Thereafter, the points mentioned in posts #1759/1760.

 

[KeepItSimpleStupid]

It's probably best posting the suggested test points or better yet, the comparison of them on a good PDM, same conditions.

e.g. No motor attached

See if you swapped any of the transistors. The 3904 for the 3906 or vice versa. See if Q1 is shorted. Remember, I forget what they are, but you have a few conditions to meet/connect when testing the PDM's by themselves.

 

[4pyros]

Joe;
Your boards look nice.
Keep up the good work.
Everything you wanted to know about electronics but were afraid to ask...LOL