Help with Water Pump

[salty joe]

I don't want to further complicate things. I was just wondering if a fuse was going to be installed to protect each pump, could the fuse simply be replaced by a reset button. Shoot, unless something got stuck in the pump I can't imagining blowing a fuse. Plus the pumps have a cover so nothing large can get in. A fuse is plenty. But thanks anyway for that link 4pyros.

My power source arrived today. It looks pretty cool. It has a pot to adjust outgoing DC volts. Where the AC comes in there a ground symbol, an N and an L. Can anyone tell me does the hot wire connect to the N or the L? There were no papers or instructions.

If I hooked the power supply to a jack to fit the connector on the pump, could I use my multimeter to determine how much amperage it draws and use that to determine the best size for a fuse?

To do the soft start it looks I'll need 4 resistors 1K, 4 diodes 1N4148, 4 resistors 33K, 4 capacitors47u and 4 timers. Did I get that right, Alec? What kind of timers do i need?

Thanks all.

 

[()blivion]

My power source arrived today. It looks pretty cool. It has a pot to adjust outgoing DC volts. Where the AC comes in there a ground symbol, an N and an L. Can anyone tell me does the hot wire connect to the N or the L? There were no papers or instructions.

Kinda dumb that it didn't come with at least some wiring instructions (/- Anyway the "Hot" should be the "L" or "live" if our terminology is synchronized. Alternately the N terminal goes to the wider blade/slot of your electrical plug, the skinnier blade/slot goes to the L, and obviously the ground pin goes to the ground terminal+case. However, it will prolly work with N and L wires switched unless you have the neutral wire in your house grounded, then it *MAY* trip a breaker. It may also freak out your GFCI breaker if you have it wrong. Unless something is somehow way non standard, then it's not going to be critical.

Now if your not sure and you want to test it... and this is not the safest thing, but it's my tried and true method for testing things when I don't fully trust them. Wire it up the way you think is best with as many circuit protections as you can cram in *OBVIOUSLY NOT WHILE IT'S PLUGGED IN*, Stand way back and plug it in; then quickly pull it back out in one quick motion, not even trying to run the device. Do this while being careful to touch only plastic. If there is a problem it will trip one of the several layers of protection or give you some indications that it's going to. If not. . . plug it in for longer and longer each time. Alternately you can use the switch on a power strip instead of plugging it in and pulling it back out. It should be obvious that things are good when you reach < 5 seconds and nothing bad happens. Do this at your own risk though, and use common sense not to touch anything electrically conductive and so on. You may want a fire extinguisher and a helping hand that knows CPR near by too. (very unlikely to actually need them.) A freshly electrocuted healthy person can almost always be saved with the proper application of CPR.

Low voltage panel mount breakers. Something like these?
**broken link removed**

I'm thinking that's what hes saying. They use them in serge protectors/power strips. I have a few of the individual units too. They are usually for use at = or < 10A (and of course < 120v.) The advantages to these devices is that they can blow more than once and you can reset the circuit quicker when it happens. I'm not sure if they trip faster than fuses blow, on the contrary it seems that my power strip takes quite a while to trip when I over load it.

If I hooked the power supply to a jack to fit the connector on the pump, could I use my multimeter to determine how much amperage it draws and use that to determine the best size for a fuse?

Not with your average multimeter, no. You would need to sample the starting conditions 100's of times for each and every pump using a shunt based ampere meter and a peek detector. Then do a statistical analysis on the resulting data to figure out exactly what fuse rating would be ideal. It's easier and close enough to just guess then use trial and error. 5 amps per pump is my educated guess for a decent fuse rating, going on the safe side of course. Keep reading. . .

I don't want to further complicate things. I was just wondering if a fuse was going to be installed to protect each pump, could the fuse simply be replaced by a reset button. Shoot, unless something got stuck in the pump I can't imagining blowing a fuse. Plus the pumps have a cover so nothing large can get in. A fuse is plenty. But thanks anyway for that link 4pyros.

Yeah, fuses are cheaper and easier to come by anyway. And under normal operation your not going to blow what ever is installed. Even if you do your not going to want to be able to just "flip a switch" back to the on position right away, because if it does blow out something is almost definitely wrong and needs inspection and retesting before you power things back on for real.

If it were my choice, I would use INSULATED female quick connect terminals and car fuses (the slot style, not the glass tube style). You can normally get both items at even the smallest of hardware stores, for less than $10 total. These fuses are closer rateing to the voltages we are using in this project also. Plus in one trip and for the same price you can get an assortment of sizes to fine tune the over current "blow out" point. Id say five amps per pump (orange color normally) is a good fuse size starting point. I wouldn't go over 15 amps per pump, or there is no point in having fuses at all.

Do note also that fuses are typically installed to protect from *FIRE* and not meant to protect one from electrocution (including your aquatic inhabitants). GFCI breakers as well as other techniques are for protecting one from electric shock. Also, both fuses and breakers have a 50/50 chance of protecting the up stream system from permanent damage caused by down stream failure. Note though that this is not really the intended purpose, just a common consequence of their use. You shouldn't rely on it, a fuse for the whole controller should be installed for this reason. About 15~20 amps should do. For this connection you could use one of the mini breakers instead if you really want to.

Finally when your building this circuit, if any thing blows right away, suspect wrong wiring first. After you CAREFULLY inspect things and it seems good, THEN you can up the protection devices rating by 5 amps. If it still blows/trips the protections then AGAIN check the wiring, ONLY BETTER THIS TIME. Only after you have exhausted all these things should you suspect faulty parts. I wire at least one thing backwards just about every time I make a circuit, comes with the territory.

Until next time. . .

 

[salty joe]

Thank you Alec and ()blivion for coming up with a soft start.

I'm looking at the schematic from post 176 and am not sure if the part labeled "timer" is a component or just a label. It seems to me if it were a component, it would have more than one wire hooked up to it. But I learned a long time ago that things are not always as they appear. Especially when treading in unfamiliar territory. Any help here would be much appreciated.

Maybe just one fuse where the DC enters the circuit would be my best bet. Would the fuse be connected to negative DC since it is carrying the electrons?

Am I correct to assume that only 1, or only 2, or only 3 pumps could be run with this circiut?

I appreciate the safety cautions. I respect all things electric. I have a bunch of GFIs in paralell in the fish room, so there is safety and half the tank does not shut down if something trips a GFI.

BTW, I was working on a friend's house who does stained glass work and he is going to loan me his big round magnifier with built in light, this thing is floor mounted with a swivel-it's gonna be nice when I solder.

 

[alec_t]

am not sure if the part labeled "timer" is a component or just a label

Sorry for the confusion. It's a label, referring to the group of components U1a, C1, D1, D2 and the pots U2, U3.

Maybe just one fuse where the DC enters the circuit would be my best bet.

Provided a soft-start circuit is used a single fuse should be ok.

Would the fuse be connected to negative DC since it is carrying the electrons?

The electrons flow from the DC negative line via the circuit to the DC positive line, so it matters not whether the fuse is in the negative or positive line. Fuses aren't polarity sensitive.

Am I correct to assume that only 1, or only 2, or only 3 pumps could be run with this circiut?

The circuit was designed for 4 pumps and has 4 independent control modules accordingly. It will work happily with fewer than 4 pumps connected. Any unused module will draw negligible current.

big round magnifier with built in light

I envy you that. As I get older I think I might have to invest in one of those! Components these days seem much more fiddly than when I were a lad.

 

[salty joe]

Thanks.
The 33K and 1K resistors are both available in 1/2w and 1/4w.

The 47u capacitor is available in 50v and 16v.

Can you guys please tell me what parts will be best for this soft start?

 

[alec_t]

1/4W resistors are fine (they are only dissipating microwatts!). 16V for the caps is too close to the 12V you'll be using, so go for 50V. (As a rule of thumb, cap voltage rating should always be at least double the working voltage.)

 

[4pyros]

(As a rule of thumb, cap voltage rating should always be at least double the working voltage.)

25 volt caps would be fine too.

 

[salty joe]

Parts are on the way. Thanks.

 

[salty joe]

The parts for the soft start got here today. The jacks arrived a little while ago & I lucked out-they're the right size.

I'm gonna re-read this thread, practice soldering tiny things, try to figure out the arrangement and this weekend start to make a module of this controller. Hope so anyway. It has been really interesting to learn a little electronics, thanks all for the help. Crunch time!

 

[alec_t]

Hope the build goes ok. Keep us posted.

 

[salty joe]

I thought I was ready to solder, then I started reading and got confused again.....geez.
In the scematic from post 99, the capacitors that are polarity sensitive are shown with a rectangle and a solid black rectangle. Does the solid black rectangle represent negative? I figure it must because it always faces ground, but need to be certain.

Concerning the four CD40106. All four of them will have pin 7 connected to ground and pin 14 connected to the 12V coming from the timer supply. Then depending on which pump module, pins 1 & 2, 3 & 4, 9 & 8, and 11 & 10 get hooked up. So each CD40106 will have 4 pins connected. Is that right?

Oh, and thanks for the tip awhile back about hooking all the pots up the same way so that I can operate them in a consistant manner.

 

[alec_t]

Does the solid black rectangle represent negative?

Yes. It's the standard European symbol.

Concerning the four CD40106

No. You need only one CD40106. It contains six Schmitt inverters: you will be using four (one per pump module), leaving two unused. Check the datasheet. Module 1 involves pins 1 and 2, module 2 involves pins 3 and 4, etc. Pins 7 and 14 are ground and +V respectively, for all four modules. The input pins of the two unused inverters should be connected to ground.

 

[salty joe]

OK thanks, it's amazing one tiny chip can do so much.

I looked at the datasheet and noticed from the functional diagram that all the even numbered pins were grouped together. I also noticed on your schematic that odd numbered pins always went to ground. But then it seems like everything is connected to ground at least in a roundabout way. Anyway, what I'm not sure about is of the four unused pins (5, 6, 12 & 13), are all four unused pins considered inputs, or only pins 6 & 12, or what?

 

[alec_t]

I looked at the datasheet and noticed from the functional diagram that all the even numbered pins were grouped together.

As you noted, that's for function. (The actual pin-out is different.)
In the datasheet each triangle shape represents an inverter. The input is on one edge of the triangle and the output is the little circle (denoting inversion) at the opposite apex.
Pins 1,3,5,9,11 and 13 are all inputs. Pins 2,4,6,8,10 and 12 are all outputs. So unused pins 5 and 13 should be grounded. Do NOT ground pins 6 or 12 or bad things may happen to the IC! Take anti-static precautions when handling the IC.

 

[salty joe]

Thank you sir.

 

[salty joe]

I got the timer supply soldered. I think the solder joints are good. They seem smooth and shiny. I tugged on a few of them and they are tight. The leads from C2 and C3 were long enough to reach pin 1 from the 7812 regulator, so I wrapped the leads from those capacitors along with a hookup wire for the pump around the regulator pin and soldered them together. I hope this is not bad practice.

I was going to keep rolling, but am not sure if it makes a difference how the jack for the pump gets connected. I determined which tab on the jack connects to the pin & which connects to the "not the pin". Does it matter which gets hooked up to regulater? The third tab on the jack goes to ground, right?

That's the best I could do with my camera.

 

[alec_t]

I hope this is not bad practice.

If it works, it works .

Does it matter which gets hooked up to regulater?

Yes. A power jack with three connections includes a switch, which you don't need here. Inserting a plug in the jack opens the switch. You need to use a multimeter to identify which tab becomes disconnected by the switching action and make sure you don't use that one. Not knowing your pump's peculiarities I can't say which connection +V should connect to. In many appliances the central pin of the connector is +V, the sleeve is -V (ground); but you can't guarantee that. The effect of transposing the two required tab connections is that the pump will run backwards.

The third tab on the jack goes to ground, right?

NO. Don't connect any of the jack terminals to ground.

 

[salty joe]

Thanks for the info on the jack. Thanks also for the tip to use a long wire for ground. I can see where that's going to make this build easier.

 

[salty joe]

I just soldered the mosfet by twisting the source and gate together with a wire ran to ground. I don't understand how the hookup works on the other side of the mosfet. Was going to install the soft start, but got stuck. Can you help out for this hookup, please?

Is that little figure that looks like a bolt at the mosfet the symbol for gate?

 

[alec_t]

I just soldered the mosfet by twisting the source and gate together with a wire ran to ground.

Oh dear. Only the source should be connected to ground. The FET gate (check the datasheet for the FET you have, to identify the gate terminal and indeed all three terminals) should connect to the pots and appropriate IC pin. The 'bolt' symbol is in fact an arrow-head symbol and represents an internal diode inherent in the FET. Ignore it. The FET drain terminal connects to the pump. My schematic shows g,d,s to help you.