Help with Water Pump

[salty joe]

@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.

I have a mechanical timer but no relay or coil.

@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.

Not sure which connections need desoldered. Could I just cut the input wire and connect it to my 24V DC supply?

 

[KeepItSimpleStupid]

Not sure which connections need desoldered.

Agreed. There either was no pic or the wrong one or the UPLOAD box is placed wrong. In any event, I swapped the file names on my computer and uploaded the proper pic. It should be clearer now in that post.

Could I just cut the input wire and connect it to my 24V DC supply?

I don't see why you couldn't cut it unless you want to sell the non-butchered controllers with or without pumps. I used alligator clips. You can cut the plug off the AC input cord, solder wires to the AC Input pads or use clips. It doesn't matter.

Check the voltage at the DC-out connector before connecting a pump!

 

[alec_t]

When the tips wear it will no longer work, the plunger will stick out of the tip,

Depending on tip shape you can sometimes overcome that by slipping a short length of small diam silicone rubber tube over the tip.

 

[()blivion]

ARGH!!!.... damn the Internets when it doesn't send me thread updates.... (-.-) Whatever.

When the tips wear it will no longer work, the plunger will stick out of the tip,

Yeah, the Teflon tips won't last long if you do a lot of work. Especially if your iron is extra hot. The silicon tube trick is a good idea. Really they should just come with a silicon tip. But then again the normal tips are not all THAT expensive. As for Joe, I can hardly see him burning up more than one. I got mine from Radio Shack (the cell phone store) for 10$ and it came with two tips.

If all Joe is doing is lifting two resistors though I would just say straighten whats hanging out, heat, then lift the part with a pointy tool. Occam's Razor at it's best really.

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

Hummm.... Agreeable but I need to think about this one. It's true that this project could be better served on a micro now that it is what it has become and could further be. But hasn't it been said once or twice (usually directly to me) that this board is about finished by now? I don't blame you for thinking about it though, I too clearly have kept coming back to this thought. Habit I guess. -/)

Anyway, you can PM me with what you had in mind and I'll definitely hear you out. And pointing me to the datasheets for the dev boards and the exact PICAXE you have would be cool too. Useful information. I'll get back to you for sure on this eventually.

Also, newhavendisplay has some good deals on caricature LCD modules in the "special offers" section. Let me know if you find something you like. Unless you have a better source for such things.

 

[KeepItSimpleStupid]

You guys got me curious about Silicone rubber: Here is an interesting datasheet: https://www.electro-tech-online.com/custompdfs/2012/07/rubber_e.pdf

Seems very reasonable.

 

[salty joe]

@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 cut those two resistors you marked and sure enough, there is 10.39V coming out of the jack.

I bought one of those Radio Shack soldersuckers awhile ago and could not get it to work. If someone wants it it's free. Free shipping too. Someone wondered what I had planned for the OEMCs. I have 5 untouched OEMcs. I only want the knobs for the pots. Anybody wants the 5 OEMCs they are free too. Free shipping.

I know that solder wick will come in handy KISS-thanks.

I connected a pump to a 6V battery and from what I can tell with my cellphone stopwatch, the time to ramp up to full speed is about .4 sec., the same time as 12V and 20V. I ran the pump 10- 15 times and a couple times the pump hesitsted for maybe 1/2 sec. I thought it might have been from oxidation on the battery posts so I scraped them shiny and did not see any more hesitation.

 

[ronv]

Yea!!!!!!!!!!
Lets build some.

 

[KeepItSimpleStupid]

The secrets to soldersucking are:
1) Lots of solder
2) Do it quick

#1, might be counter-intuitive, but it's true. You have to have a large thermal mass to start with, well not necessarily. I tend to remove what you can, then add solder. Get it nice and warm and quickly suck.

I did have a Radio Shack version and they don't perform well, but they do work.

You can use Solder-Wick in the same way. You might have to add solder to remove solder.

With the non-lead solder the temperatures are hotter.

 

[alec_t]

I have 5 untouched OEMcs. I only want the knobs for the pots. Anybody wants the 5 OEMCs they are free too.

Aren't you going to salvage anything else from them? Whichever version of the PDM you build I think at least inductors and ripple-tolerant low ESR caps will be required. The inductors aren't particularly cheap and we haven't established if you can easily source values around 50-150mH with a 5A or so current rating.

I connected a pump to a 6V battery and from what I can tell with my cellphone stopwatch, the time to ramp up to full speed is about .4 sec., the same time as 12V and 20V. I ran the pump 10- 15 times and a couple times the pump hesitsted for maybe 1/2 sec. I thought it might have been from oxidation on the battery posts so I scraped them shiny and did not see any more hesitation.

That's good news. Helps with the design.

 

[salty joe]

Aren't you going to salvage anything else from them? Whichever version of the PDM you build I think at least inductors and ripple-tolerant low ESR caps will be required. The inductors aren't particularly cheap and we haven't established if you can easily source values around 50-150mH with a 5A or so current rating.
QUOTE]
Ohhhhh. Thanks. In that case, the deal's off for the OEMCs.

Thanks for the tips KISS. I just found the solder sucker awkward and frustrating. I think I'll like a wick a lot better. Deal is still on for the solder sucker.

 

[ronv]

Whichever version of the PDM you build I think at least inductors and ripple-tolerant low ESR caps will be required. The inductors aren't particularly cheap and we haven't established if you can easily source values around 50-150mH with a 5A or so current rating.

Alec, I think the simple FET switch with retry now meets all the requirements. Doesn't it?

 

[alec_t]

I think so.

After further simulation I found adding the L and C as I suggested back in post #757 isn't such a good idea. With a pulsed input on the FET gate the L has the effect of slowing down the action of the desired current-limiting and results in excessive peak currents (albeit for only millisecs). So it's back to the previous arrangement, doing the speed control externally of the PDM by changing the PDM supply voltage.
Attached is a minimal PDM design with the following features, to get Joe started and allow speed control to be added later :-

Module applicable to wave or tide controller,
Cost-effective using components to hand or readily available where possible,
Constant 3A current limit to handle in-rush at start-up and rotor-lock afterwards,
Module trips off if current > 3A for given time (trip delay),
Adjustable trip delay,
Module off for 32 sec then circuit resets automatically for a retry,
Transient voltage suppression,
Power supply protection against reverse current,
An output for driving fault LEDs and an audible alarm.

This version may not have all the bells and whistles, but should give reasonable protection to the pump, the power supply and the PDM itself. Happy to correct any errors or omissions you guys may spot, and glad of any suggestions for which TVS to go for. If the resettable fuse proves elusive a 3A quick-blow wire-ended fuse (as per the OEMC) could substitute?

 

[ronv]

The only thing I might change is the current limit. Maybe closer to 4 amps so that there is enough voltage to fully turn on the FET in the pump.

 

[alec_t]

Perhaps. But if 3A is flowing in the pump isn't the pump FET already fully on? Steady-state (post start-up) running current (rotor free) is only ~1.2A, so the FET would be expected to be fully on at 1.2A.

 

[salty joe]

It feels like we're getting close. Thanks guys.
The best I'm going to be able to do for the next two weeks is get parts ordered and follow online.
Quite awhile ago I promised to chaperone a group of high school kids to Florida. We'll be on a redeye Friday to Fla. They really had to twist my arm....As soon as we return, we go to Lake Erie for our week of family vacation.

 

[KeepItSimpleStupid]

5 V or 12 V logic power? 5V allows using the OEMC without modification although you only need 1 logic supply, but 5V may make it difficult to fully turn on a FET.

So, speed control is basically power supply. OEMC or something else. In any event, the logic required would likely be:
1) System runs at low speed with no signals in
2) system runs at high speed with a signal in (NOT FEED)
3) Do the regulators have to be disabled when not in use? What effect would the above circuit have on turning the regulators on at the same time as turning the motors on?

Shouldn't Joe figure out what the minimum voltage he could run the pumps at and be satisfied? i.e. Try to stay below 18 VDC. I tried to call Melexis last Friday, but they, I guess were at lunch and I forgot to take that into account. I want to ask about the datasheet.

 

[ronv]

Perhaps. But if 3A is flowing in the pump isn't the pump FET already fully on? Steady-state (post start-up) running current (rotor free) is only ~1.2A, so the FET would be expected to be fully on at 1.2A.

I'm thinking about the initial start up or if the motor is stalled. 3 amps (in current limit) voltage to the pump is 6.45 volts and gate to source voltage maybe 6.1 or 6.2. But your probably right. As the FET resistance goes up so will the gate to source voltage.

 

[()blivion]

Happy birth day America!!!

Every one over the legal age make sure to get good and drunk today... OK.

(as for you foreigners, happy.... Wednesday... I guess)

 

[alec_t]

I'm thinking about the initial start up or if the motor is stalled. 3 amps (in current limit) voltage to the pump is 6.45 volts and gate to source voltage maybe 6.1 or 6.2.

Joe has confirmed the pump starts reliably at 6V, so we should be ok with a 3A limit?

BTW, I'll be off-air for a few days. See y'all next week.

 

[salty joe]

It was in the high 90s and humid when I left town and exactly the same in Florida. I like the hot weather, anything but bitter cold. I was worried about being a chaperone for a bunch of high school kids, but it was not too bad. Anyway, I am really glad to be home.

Is there any chance of reviving this thread?