Help with Water Pump

[alec_t]

I'm dying to know what's in that file.

The .asc file is just a text file listing components/values/connections for the LTSpice simulation. Nothing exciting, and not needed if you don't use LTSpice.

Is it safe to assume that the three +12V "flags" go to the Vdd pins on the three ICs? Is it also safe to assume that it does not matter which "flag" goes to any given IC?

Correct. The flag just indicates 12V is present along the wire it's shown on.

Will the 40106 get hooked up like the last circuit? Moving from the flat side of the triangle to the circle at the point of the triangle 9-8, 1-2, 3-4. Bring 12V to pin 14 then ground all unused odd numbered pins?

You will only be using 2 (U1a, U1b) of the 6 inverters inside the IC. The symbol for an inverter is a triangle with a circle at one apex. The circle denotes inversion in any logic circuit and here is shown at the inverter output point. Let's say use pins 1 and 3 as inputs, pins 2 and 4 respectively as outputs. Pin 7 is grounded. Pin 14 is +12V. Ground unused input pins 5,9,11,13.
For the CD4093 it doesn't matter which of its four gates you regard as U2a, U2b etc; just remember your choice. Pins [1,2],[5,6],[8,9],[12,13] are inputs; pins 3,4,10,11 are outputs. Pin 7 is ground. Pin 14 is +12V.

I'm having a little bit of trouble finding a .33 uf cap for C10

Try 0.22uF or 0.47uF or anything close, and change R3 to 470k or 180k accordingly (better yet, make R3 a 500k trim-pot, which would allow adjustment of the 'flick' time).

would .33 uf 1000V work

It certainly would, but is OTT and may be more expensive.

 

[salty joe]

Thank you Alec. 500K trim pot it is. Thanks for all that good info. Ordering parts tonight.

 

[salty joe]

Emitting color: Blue
Diameter: 3mm
Lens color: Water clear
Usage voltage(V): 3.2-3.4
Current(MA): 20

I want to use these LEDs to indicate when the pumps are running. Unless I've got this way wrong, the pumps will run on the 24V exactly as it comes out of the power supply.So I guess a resistor is needed for the LEDs. Is there a rule of thumb for something like this?

I tried to measure the amps coming out of the power supply by putting the multitester on DCA 200m and inserted the probes according to the manuel. When I touched the probes to the + & - of the power supply, it sparked. I don't think I fried anything, but something isn't right.

 

[KeepItSimpleStupid]

Yep, Rule of thumb, by example:
The resistor needs to be less than (24-3.4)/20e-3 ohms. You can do the math, then pick a value that's close.
You can recalculate I by using I = (24-3.4)/(The R selected) although it should not matter much.

Since P = (I^2)*R, you can check the power required for the resistor. The resistor wattage has to be greater than what you calculate. 1/8, 1/4, 1/2 and 1W are typical wattages available.

Measuring current
It's very likely you blew the current fuse in the DMM.
You evidently noticed that there are different connections to the test probes when measuring current.

To measure current, the ammeter is inserted in series with the load, so you pull the wire to the (+) of the supply and effectively "splice" the ammeter into that lead.


Measuring

 

[salty joe]

Yep, Rule of thumb, by example:
The resistor needs to be less than (24-3.4)/20e-3 ohms. You can do the math, then pick a value that's close.

OK, I follow the supply V (24) - usage V (3.4). That yields 20.6. Now, divide 20.6 by 20e-3 ohms. I assume the 20 is the 20 MA for the LED. What is e? It seems like amps and ohms are unlike terms so should not be able to add or subtract. What is the rule of thumb? Subtract 3 ohms?


To measure current, the ammeter is inserted in series with the load, so you pull the wire to the (+) of the supply and effectively "splice" the ammeter into that lead.


Makes sense. To measure the amps would the + wire need to be cut and the gap bridged with the DMM probes?




Since P = (I^2)*R,

What does I^2 mean?

It's very likely you blew the current fuse in the DMM.

How can I check the current fuse in my DMM?

 

[KeepItSimpleStupid]

To measure the amps would the + wire need to be cut and the gap bridged with the DMM probes?

Yes. The ammeter can go anywhere. In the positive lead or the negative lead. With the DMM, it won't matter what polarity you use.
"conventional current" flows from positive to negative.

[latex]P=I^{2}R[/latex]

P = Power (Watts)
I = Current (Amps)
R = Resistance (Ohms)

 

[alec_t]

Don't try measuring the current the power supply can provide. It's much greater than your DMM can handle! Just assume it's 'enough'.
If the maximum current range of your meter is only 200mA then you can't even measure the current a pump draws (which can be several amps peak). It's not surprising there was a flash and a bang. Presumably the power supply (which should have built-in overload protection) is still working? As KISS said, you probably blew the fuse (if there was one) in the meter. Unfortunately the fuse is unlikely to be readily accessible.
Rough calculation for the LED:
Don't run it at max current, so let's say 14mA (makes the sums easy). LED voltage ~ 3V, so resistor needs to drop 24-3 = 21V. So resistor value = 21V / 14mA = 21/0.014 = 1500Ω (1k5).

What is e?

'e-3' is short for ' x 10 to the power -3', in other words 0.001.

What does I^2 mean?

I 'to the power of' 2, in other words 'I squared'.

How can I check the current fuse in my DMM?

Set the meter to its maximum current range, connect the meter + probe to the +24V rail, connect the meter - probe to one terminal of a good old tungsten-filament mains-rated lamp (say 60W or 100W), connect the other terminal of the lamp to the 24V supply ground rail. If you get a reading > 20mA or so the fuse is ok.

 

[salty joe]

Thanks guys. Yes, lucky for me the power supply seems fine. Thanks for the DMM test. It was inexpensive, but still I hate to ruin things.
Can't wait for the parts to get here.

 

[KeepItSimpleStupid]

LED specs are sometimes difficult to read. I was taking you 20 mA as a "typical value". Only the datasheet knows for sure. Note that there is also a range for Vf. As time goes on, the LEd will lose intensity, but it generally doesn't burn out.

The current fuse or fuses can generally be taken out of the meter and tested using the resistance mode. If it reads infinite, it's bad. If it has a low resistance, it usually means it's good. Sometimes it isn't. That has happened to me twice.

 

[salty joe]

Ther will be times when I want to temporarily reduce water movement. Can I do this by turning the pot on the power supply to less than 24V without causing damage to anything?

 

[alec_t]

The power FETs typically need a few volts on their gate terminal to switch them fully on. If they are only 'half on' they may run hot (but against that if the volts are down the current will be too, so heating may not be noticeable). So providing you don't turn the wick down too far you should be ok. The 40106 will tolerate a wide voltage range.

 

[salty joe]

Thanks.

 

[salty joe]

How about a pot between the controller and the pump?

 

[alec_t]

Not very practical because of the 1-2A motor current. You'd need a very expensive high-power pot. Stick with lowering the supply volts.

 

[salty joe]

R3 is getting replaced with a 500K pot. To adjust the idle pumps to flick every 40-50 seconds, on the 4020 would pin 5 to C10 be the better choice? Or pin 7 to C10?

The parts got here today so I've been taking notes, trying to wrap my head around the tide schematic. Hope to start soldering this weekend. I'm pumped-pun intended.

I ordered a fuse holder and 10A fuses. I was going to install the fuse where 24V enters the controller. Is the placement and size of the fuse right?

 

[salty joe]

After looking at the 4020 datasheet, it does not look like any unused pins go to ground. Is that right?
You know you're hooked when you lay in bed thinking about how this or that part gets hooked up.

 

[KeepItSimpleStupid]

Only inputs are affected and that would be pins 10 and 11. I believe you have them connected to something.

 

[salty joe]

I believe you have them connected to something.

Yes, thank you.

 

[alec_t]

To adjust the idle pumps to flick every 40-50 seconds, on the 4020 would pin 5 to C10 be the better choice? Or pin 7 to C10?

Pin 7 would be best.

After looking at the 4020 datasheet, it does not look like any unused pins go to ground. Is that right?

Correct.

I was going to install the fuse where 24V enters the controller. Is the placement and size of the fuse right?

Fuse size and placement sound ok. The fuse is there to protect the motors and power supply. (Fuses in general act too slowly to protect most electronic components). Good luck with the build.

 

[salty joe]

Many thanks.