Help with Water Pump

[salty joe]

Collin55, thank you very much for that schematic. It shows 12v, my pumps are 24v but if that works I'm all for building it.
Boncuk, these pumps are for aquaruims and have no air bladder. Thanks.
Reloadron & ronsimpson, The time delay https://www.electro-tech-online.com/custompdfs/2012/01/70175105.pdf shows a mechanical life expectency of 10,000,000 operations but under full load only 10,000 operations. That's only a little more than a month at an operation every 30 seconds. What's the deal with the huge discrepency in operation life expectencies?
()blivion you have it right when you said "I think the different pumps need to NOT be synchronized with each other. And ideally the duty cycles would vary a bit over time." I'm thinking one controller will make two pumps do the same on/off cycle and another controller will handle two more pumps. They will be set about the same, but not exactly the same so sometimes all four pumps would almost operate simultaniously and sometimes almost opposed and most of the time somewhere in between. That would hopefully create random currents.

alec_t, Thank you for that schematic, I will study and try to understand it tommorrow.

If it would hold up for the long haul, a pre made time delay is attractive. On the other hand, I would really get a kick out of building one from scratch. Plus if I built it, I might get a clue as to why the schematic calls for certain parts in certain places. I'm leaning towards building one. Building things is fun.

You guys have been so helpful-I can't thank you enough.

Joe

 

[salty joe]

When this reef tank project is done would anyone be intersted in a picture?

 

[colin55]

It shows 12v for the circuit , but the relay can handle 24v, or 240v. You just need a 12 supply for the circuit.

 

[()blivion]

I would look at pictures if you post them when your done. Of the project and of the tank. I love reef environments, they are so attractive. But IMO to much of a pain to deal with and to high a cost. One little F-up and your $1000's of dollars down and left with dead pets and a broken heart.

You said:
"What's the deal with the huge discrepency in operation life expectencies?"

Relays use metal contacts just like a real switch, metal contacts wear out. For a brief time when the contact is either closing or opening, there is only a tiny portion of metal in the switch conducting power. Under low or no load, this is not a problem because there is not a lot of power going through the small contact area, so it doesn't heat up and you get your 10,000,000 operations (which is roughly JUST how many times the physical switch can open and close) With full power though, it starts to act like a welder or plasma cutter and burns the contacts every time it opens and closes. As expected this beats up the contacts more than normal and lowers the life time. I should also point out that those operating numbers are really just a shot in the dark that shouldn't be taken seriously. Real devices are effected by many many factors, It could last for as long as either number under either load condition. I personally wouldn't trust them.

Relays are an antique technology that's bulky, and prone to failure. If what your mostly after is long life, then you can't go wrong with all solid state instead (such is the case in alec_t's schematic). In theory solid state systems should never burnout from normal use. Just replace the heavy relay with a heavy MOSFET and some back EMF protection and your good to go. Any one here could point you in the right direction. I'm partial to salvaging parts myself, but you can buy them if your would prefer. Here is a good part from DigiKey.com: IXTP32P05T-ND. It will cost you 16$ + S&H for 10 of them. Mouser has an even bigger selection too. Go with the TO-3P package if you do get your parts from Mouser. A little more pricy per part, but they can handle WAY MORE POWER and are a little more forgiving should you F-up.

You shouldn't need a heatsink for the transistors. If they get hot something is wrong.

C U L8tor

*Edit*
Turns out I hit the buttons wrong in the search bar for DigiKey. They do have a good selection of transistors after all, including parts in the TO-3P package.

 

[salty joe]

You sold me on building my own. I remember keeping a file and a pack of matches for a feeler guage in my truck to clean and set the points when the truck started running rough. I don't want to trust a reef tank to a set of points. It's amazing how much better modern vehicles are, but I sorta miss being able to recognise everything under the hood, the ease of an engine rebuild, I don't miss all the mantainence.

 

[Reloadron]

Great Joe and if you need any help just return here or if you need direct help drop me a PM. Pictures when done!

Ron

 

[salty joe]

Thanks Ron, I appreciate that. I promise pictures of the circuit and then a little down the road of the tank.

 

[salty joe]

Here's 2 circuits for 2 pumps. You can control each pump separately. The chip has 6 gates. **broken link removed**

Collin55,
Does each circiut control one pump, or does each circiut control two pumps?

I noticed the 74c14 is hooked up differently, how does that affect what the pump or pumps do?

How would the pumps on/off be adjusted? Did not see a pot-at least not the one symbol I learned for a pot.

I think yours is an elegant circuit for achieving control with so few parts. I don't have it figured out yet, I'm working on it.
Thanks a million

 

[Reloadron]

You want to take a closer look at Alec's circuit.

However, to answer your question each of Colin's circuits would drive two pumps off the relays. However, it is a rough circuit, for example the value of the .1uF caps is much too low, note Alec brought it up to 100uF. Additionally Alec used transistors to switch the pumps on and off. The timing principal in both is the same. Both use 100K pots to adjust On and Off times. Alec using the more traditional pot symbol. The pots are the symbols in series with the diodes.

Does that help?
Ron

 

[colin55]

They are not .1uF
You may need 10u
I would only drive one pump per relay
They are trim pots

 

[salty joe]

Ron, that does help-thanks.

Collin, thanks for the update. Does your circuit allow for independent control of both run time and not run time? How come the IC is connected differently in the two schematics?

Alec, I had a hard time opening the updated asc file, but finally got it opened and printed. Wow, you not only made a schematic you also made a plan for the build. As a total beginner I need that. Thank you very much. The updated circuit will control one pump, is that right? On the first circuit that controls four pumps, can each pump be independantly controlled?

Joe

 

[colin55]

The 74c14 has 6 gates (Schmitt Inverters) Each trim pot controls the on or off time

 

[salty joe]

Thanks. How come the IC is connected in a different way on each schematic?

 

[alec_t]

The updated circuit will control one pump, is that right?

I don't recall updating my circuit. Mine controls 4 pumps.

On the first circuit that controls four pumps, can each pump be independantly controlled?

No. You specified that the pumps would be operated in pairs. U3 and U4 independently control the 'on' and 'off' times of the first pair (pumps 1 and 2). U5 and U6 independently control the 'on' and 'off' times of the second pair (pumps 3 and 4). It would, however, be a simple matter to extend the circuit so that all four pumps had independent control.

 

[()blivion]

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Edit: The following comments assume that your asking about the difference between the left and right side of colin55's schematic. And not actually talking about the difference between colin55's schematic and alec_t's schematic, which in fact uses a different but similar part. However, the point I make about needing to power the chip is still valid for both situations.
*********************************************************************

"How come the IC is connected in a different way on each schematic?"

It's not really connected differently, that's just a power wire for the 74C14 chip. It's omitted in the right side of the picture because one 74C14 chip has 6 "gates" (the triangle shapes) for every two power wires, so the left side covers it. The 74C14 is not quite like a resistor or capacitor that can just be inserted into a circuit some where and work. It needs to have it's own power to do what it does. Most schematics are less than obvious about that because it's considered common knowledge, even if I would prefer they didn't do that.

What follows is a link showing you the guts of the 74C14 and some different ways to hook them up. In the first picture you can clearly see that pin 7 is a power wire and is connected to ground, just like in the left side of colin55's schematic. Also, the commentary for the third and fourth picture down briefly explains colin55's circuit. You can ignore the rest of the web page.

http://talkingelectronics.com/ChipDataEbook-1d/html/74C14.html

 

[alec_t]

Here's the extended circuit to give separate control of both the 'on' and 'off' periods of four pumps completely independently. Note that the pumps are each represented here as an inductor in series with a resistor. BTW, the 'asc' file that you had difficulty opening is for running a simulation of the previous circuit in LTSpice.

 

[ronv]

Alec,
Since the 12 volts is only running 1 CMOS IC how about just a zener regulator?

 

[alec_t]

Yes, a simple zener reg could do it. I was feeling generous with the mA ;-)

 

[salty joe]

Thanks ()blivion for the explanation.
Alec, I saw the simulation of the previous circuit in LTSpice & thought it was another cicuit altogether, which kinda threw me- thanks for clearing that up. I'll probably build your schematic that controls the pumps in pairs first, the second one will most definitely be useful too.

 

[alec_t]

I'll probably build your schematic that controls the pumps in pairs first

In that case, here's a revised form of the 2-pairs circuit which includes IC pin numbers and constructional notes. It incorporates Ronv's suggestion for a simplified 12V supply.