Help with Water Pump

[salty joe]

Thanks a whole lot, Alec. I'll study it and get it hooked up.

 

[salty joe]

On the speed module Mk1, C2 is 390n. Are n and pF synonymous?

https://stores.ebay.com/Tayda2009/_i.html?_nkw=390+capacitor&submit=Search&_sid=872591586

Also to set min speed calls for 100K log pot. Would a trimmer be OK?

 

[alec_t]

Are n and pF synonymous?

No. 'n' is short for 'nF' and stands for nanoFarads (1nF = 1000pF). 390n = 390000pF = 0.39uF.

Also to set min speed calls for 100K log pot. Would a trimmer be OK?

Depends how often you think you'll need to adjust the pre-set minimum speed. I was guessing the max speed would be set-and-forget (i.e adjust just once to give an average 18V or so across the pump), hence a trimmer for that; but you might want to tinker more with the 'feed' (min) speed, hence a pot. Your call. Doesn't matter greatly if the controls are log or linear. BTW, the principle of operation of the speed control is wholly dependent on the pump's commutation briefly dropping the pump coil current to zero or thereabouts between successive coil energisations, as per the two fan motors I tested the control with. There's a high probability your pumps will behave the same way as the fan motors. There's no guarantee, though.
Once again, it would be advisable to build and test one speed control before going into mass production The simulation assumed a max pump speed of ~ 3000rpm. So we may need to fine-tune some component values if your actual max speed is wildly different.

 

[salty joe]

Thanks, I'll look elsewhere for the right cap. Meanwhile I'll start in on the PDM15s.

As far as speed control-I'd like to slow the one pair of pumps well below 1/2 speed-just enough to keep the filter from getting stagnant.

I'm thinking all trimmers. I'm glad log or linear will do.

Thanks!

 

[KeepItSimpleStupid]

Joe:

BTW: Capacitor in SERIES obey 1/Ct=1/c1+1/c2....+1/Cn (similar to resistors in PARALLEL)

and capacitors in PARALLEL add: Ct=C1+C2+C3+...Cn (similar to resistors in SERIES)

so a 0.1 uf || 0.1 uf = 0.05 uf or 50 nF

 

[alec_t]

I'd like to slow the one pair of pumps well below 1/2 speed

I was able to slow the fan motors right down to a crawl.

 

[salty joe]

Joe:

BTW: Capacitor in SERIES obey 1/Ct=1/c1+1/c2....+1/Cn (similar to resistors in PARALLEL)

and capacitors in SERIES add: Ct=C1+C2+C3+...Cn (similar to resistors in SERIES)

so a 0.1 uf || 0.1 uf = 0.05 uf or 50 nF

That's good to know-interesting too, thanks.

I was able to slow the fan motors right down to a crawl.

That is absolutely outstanding. Should be perfect-thanks.

If I cannot make a combo of caps to equal 3.9uf with what's on hand, will this do for C2 of the pulse width section? I had no idea there were so many different kinds of caps.

**broken link removed**

 

[alec_t]

3.9uf

No! 0.39uF (390nF) is what you want. Plastic film type.

 

[salty joe]

Thanks for catching that. I knew I had to divide by 1000-I got no excuse....
I found a good deal on this cap, the voltage is 10x what we need, is that OK?
.39uf 250V POLY FILM MYLAR CAPACITOR

I also found a couple Piezo screamers-both are 12V, 110db, and reasonably priced. One calls for 110mA and the other calls for 200mA. Is one a better choice for this project?

 

[KeepItSimpleStupid]

Joe:

I made an error in post #1365. This is correct: "and capacitors in PARALLEL add: Ct=C1+C2+C3+...Cn (similar to resistors in SERIES)"

The rules for capacitors in series and parallel is just the opposite as those for resistors. Parallel caps add and series resistors add.

 

[alec_t]

I found a good deal on this cap, the voltage is 10x what we need, is that OK?
.39uf 250V POLY FILM MYLAR CAPACITOR

That will be fine (butwill be a bit bigger, physically, than a lower voltage one).

One calls for 110mA and the other calls for 200mA

110mA is comfortably within the 200mA max current spec of the 2N3904 transistor shown in the alarm section schematic whereas the second sounder would be right on the limit. Arguably (depends on sounder efficiency) the 200mA one should be some dB louder, but if you go for that then the 2N3904 should be replaced by a beefier transistor (e.g. 2N2222 or 2N2219A) or even by one of your FETs.

 

[salty joe]

The rules for capacitors in series and parallel is just the opposite as those for resistors. Parallel caps add and series resistors add.

Thanks for clearing that up.

That will be fine (butwill be a bit bigger, physically, than a lower voltage one).
110mA is comfortably within the 200mA max current spec of the 2N3904 transistor shown in the alarm section schematic whereas the second sounder would be right on the limit. Arguably (depends on sounder efficiency) the 200mA one should be some dB louder, but if you go for that then the 2N3904 should be replaced by a beefier transistor (e.g. 2N2222 or 2N2219A) or even by one of your FETs.

Thanks, I'll get the 110mA screamer and the caps ordered. The larger cap should be no problem because I gain a lot of space taking the piezo off the board.

 

[alec_t]

If 390nF is difficult to source use 330nF instead. That seems more common.

 

[KeepItSimpleStupid]

deleted

 

[()blivion]

Ah... Vietnamese, that explains why I was having trouble trying to translate it. I was thinking it was Chinese.

 

[KeepItSimpleStupid]

Just use translate.google.com and auto-detect language.

 

[salty joe]

Orange juice on the skin post bai or len dien dan crab weOr has hand grind dap dien dan enrich manhCam on tat ca.Ilayaraja melody 1 evlerin glad ve.
This is what I got. It's supposed to be English. Just doesn't translate?

Thanks Alec, the caps are on the way.

On the speed module, on U1a I asigned pin 2 for Isense, pin 3 for Iref and pin 1 for output. Energize pin 4 with 12V, ground pin 11 and install a 0.1uf cap between 4 & 11. For Uib, I assigned pin 12 for spd, pin 13 for input and pin 14 for output. Ground unused inputs.
I am confused by the 12V and ground wire at U1b. I wont get to the speed module for awhile, just wondering.

 

[alec_t]

It's supposed to be English. Just doesn't translate?

It's spam. Hopefully the mods will suppress it.

On the speed module, on U1a I asigned pin 2 for Isense, pin 3 for Iref and pin 1 for output. Energize pin 4 with 12V, ground pin 11 and install a 0.1uf cap between 4 & 11. For Uib, I assigned pin 12 for spd, pin 13 for input and pin 14 for output. Ground unused inputs.

All good. You're getting the hang of this electronics stuff!

I am confused by the 12V and ground wire at U1b

Sorry. Ignore those; they're only in the schematic for the benefit of the simulator. I should have removed them before posting the pic.

Edit: BTW those two spare opamps in the IC could be used in a second speed controller if it's convenient. Depends how 'modular' you want to go.

 

[salty joe]

All good. You're getting the hang of this electronics stuff!

That's nice of you to say, thanks. It's all pretty mysterious stuff to me and I appreciate the opportunity to work with electronics.

they're only in the schematic for the benefit of the simulator.

Got it-thanks.

Under the speed set section (SSS) on the speed module Mk1 schematic, it says (1 off, for use with 4 x PWS). What does PWS stand for?

When I try to search this thread, the seach box is covered up by the top of the first post on that page. I looked through the last ten pages but did not see PWS.

 

[4pyros]

The motor grounds on the PDMs or "Power Gnd" should go right to the 20 volt supply.