Help with Water Pump

Thanks KISS-I never would have dreamed of scrubbing a circuit.
I like that idea Alec, by the time I read it, I was way into the second go round. I'll do it next time, thanks.

Just got done in fact and plugged it in. One LED is doing it's thing, and this time it's turning off completley when it's not on. Hope that makes sense.

I put my DMM on the operating LED's leads and it showed 23V or so, then a drop to about 2V, then back up to 23V so I can sorta see what's going on with this low budget DMM. No flicker ftom the other LED. Those leads show a steady 2-3V.

I have an opportunity to earn some money this afternoon so I'll run the diagnostics later. In the meantime, I left the controller running to see if the other LED starts operating later today.

I put my DMM on the operating LED's leads and it showed 23V or so, then a drop to about 2V, then back up to 23V

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Good. It's toggling as it should.

No flicker ftom the other LED. Those leads show a steady 2-3V.

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The second LED is permanently on?

No, the LEDs are hooked up with wire nuts for now. So are the pots.

salty joe said:

Those leads show a steady 2-3V.

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2-3V is not right. 1.8-2V is more like it.

Gotta run.

The second LED is permanently on?

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Sorry. I meant 'is the second LED permanently lit up' (while the first is toggling every 30 secs or so)?

2-3V is not right. 1.8-2V is more like it.

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What I would expect for the average LED when lit.

No, that LED is not on. no flicker, no nothing,
I realized what you meant and thought I had it edited. oops on my part.
I'm going to run diagnostics now.

I missed a conection and can't find wher it goes. I don't know about this attempt either. I need to walk away from this for a few days and think about how to get it right..... I'm out of some parts anyway. I am not going to give up on this-please don't give up on me.
When the parts arrive, I'll use your graph paper method Alec and for sure I will take more time. I'll also quit working when I get tired. I feel better already. ha ha and sorry.

I am not going to give up on this-please don't give up on me.

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We'll get there in the end

Thanks Alec, that's very cool of you.

Each pair of pumps is wired in tandem. The two 0.1 uf supression caps for each pair of pumps are right next to each other and straddle the + and - pump leads. Would one 0.1 uf cap work as well as two in this case? Or maybe one 0.22 uf for each pair?

The aim is to get the suppression cap(s) as close to the pump terminals as possible, to minimise RF interference. So individual 0.1uF caps are best, a single 0.22uF would be second best, and just one 0.1uF comes in third and wouldn't be so effective.

As close as possible really means at the motor. 0.1's in parallel with 0.01's can even be better. This is an area where paralleling different types play by different rules. Ceramics are best in this application BUT.... there are big BUTTS here.

OK, thanks. I have plenty of 0.1 caps. I also have a bunch of ceramic 0.01 caps.

No way can I get them by the pumps. Pump lead is the best I can do.

KISS, are you suggesting to insert a 0.01 cap on each leg of the 0.1 cap? Which would mean a total of four 0.1 caps and eight 0.01 caps.

Here is a 3 part article on bypassing: https://eetimes.com/design/analog-design/4009954/Choosing-and-Using-Bypass-Capacitors-Part-1-of-3-

I have to look at the schematic. Usually they are placed at/in the motor, possibly 2 or 3 in parallel.

Bypass caps, usually 1 are placed at power of each IC as close to the pin as possible.

KeepItSimpleStupid said:

Bypass caps, usually 1 are placed at power of each IC as close to the pin as possible.

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I can position the 0.1uf caps to make a 90 degree bend in the + cap lead at the Vdd pin and then go to 12V. The negative cap lead would ground near the Vss pin, if that matters.

I've got this sketched out the way it will go together. Great tip Alec-thank you. When the parts arrive, I think I have a much better chance for success. I was just putting parts together and ended up having to put things underneath and behind other things.

I'm thinking there was some beginners luck in the first build.

Thanks for the article KISS-I'll read it later.

Bypassising is an art and a wideband oscilloscope can help. Unfortunately "Bypass" has many meanings.

The two your looking at here is to bypass RFI , either entering or leaving. The brishes generate RFI and that's where a bypass cap is useful. The power line could contain RFI and thats where a little bypassing is useful. If this was a microprocessor based unit, then an RFI filter should be fitted to the mains.

Another form is Bypassing the power supply at the IC, When the IC switches, it draws a spike from the power supply. That CAP tends to dampen that spike. At high frequencies the leads of the capacitor act as an inductor, so now you have an LC circuit which is undesirable.

So yes, a 10 uf cap parallel with a 0.1 uf Cap ceramic is a 10.01 uf Cap, but it acts very differently with frequency. The 10 uF cap can do very little with a 100 MHz signal wheres the ceramic has a chance.

KeepItSimpleStupid said:

If the flux is left on, there is the possibility of corrosion. I'd do your final scrubbing with the IC's not in the sockets and then air dry out side in the sun. There was a recent discussion in a major test equipment group where boards coming in for repair were placed in a dishwasher.
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I'm going to solder the ICs to the board. No sockets. Is it safe to get ICs wet?

Speaking of dishwashers, my keyboard died suddenly, so I removed the keys and ran it through the dishwasher. It works like new! I thought it was a goofy urban myth.

Yep, it's safe to get IC's wet.

Well, I didn;t run a laptop keyboard through the dishwasher, but I did give it a good scrubbing and hung it outside on the line for a day. Soda isn't good for the keys.

Cell phones are is bit more troublesome to salvage, though. The LCD screens can be damaged by water. There is usually a tiny internal battery inside as well as the main battery. Removing the battery and rinsing in clear water is imperative and disassembling is recommended. Drying is accomplished by putting it in a zip lock bag full of uncooked rice. It must be thoroughly dry before powering up.

My parts showed up so I took another stab at the tidal simulation circuit. Unfortunately I'm still having trouble. At least this time it is built in an orderly fashion and I can quickly identify any part in the circuit. I'll run the diagnostics mentioned earlier in this thread either later tonight or tomorrow.

The LED is toggling but again the LED is not turning off completely. The voltage measures 24.4 and then toggles to 15.8. The LED on the idle set of pumps registers a steady 2.5 V. Not enough to make the LED glow or anything. That made me wonder if perhaps I did not hook up the 500 K. potentiometer for the flick control correctly. So here's what I did. I sent the negative side of the 0.47 capacitor (C 10) to pin seven of the 4020 integrated circuit. On the positive side of that capacitor,I connected a lead for the 500 K. potentiometer and a 390 K. resistor (R6). On the other side of that resistor I connected to pins eight and 12 on the 4093. For the other 500 K. potentiometer lead, I simply tied into 12 V.

The only problem that I know about was I had some solder connected across a couple pins on the 4093. I took a little screwdriver and scraped a groove in the plastic between those two pins. Am I correct to assume it's no use using a continuity tester for something like that because everything is so interconnected?

Shorts are shorts. They will show up as very low resistances. An ohmmeter check can generally be used to check for solder bridges. A single-edged razor blade might help you. There are some components that could prove difficult to test such as an N channel JET.

The diode test on your meter would be useful for solder bridges here too.

The voltage measures 24.4 and then toggles to 15.8.

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Voltage between which two points?

Am I correct to assume it's no use using a continuity tester for something like that

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Depends what your continuity tester is. If it's the Ohmmeter function of a DMM it should work; if it's a car bulb or fuse checker then it may not.