Need some electrical engineering assistance

[BuckeyeDennis]

Thanks for the clarification. Posts 8-10 had me confused on that matter, but reading your clarification and re-reading those posts, I think I'm getting it. But, every time I think I've got it, I don't!

So, for the sake of education, say I'm using a battery charger with a car battery for electrolysis. The battery should be connected parallel - both leads from the charger to the battery, then both leads from the battery to the electrolysis setup (positive to the anode/sacrificial metal, negative to the cathode/part to be cleaned). To check the voltage with my multimeter, I would connect the leads across in parallel as well. To check the current (as measured in amps), I would have to break the circuit from battery to the cathode and connect the multimeter in series. Correct?

You got it!

[JPG]

Thanks for the clarification. Posts 8-10 had me confused on that matter, but reading your clarification and re-reading those posts, I think I'm getting it. But, every time I think I've got it, I don't!

So, for the sake of education, say I'm using a battery charger with a car battery for electrolysis. The battery should be connected parallel - both leads from the charger to the battery, then both leads from the battery to the electrolysis setup (positive to the anode/sacrificial metal, negative to the cathode/part to be cleaned). To check the voltage with my multimeter, I would connect the leads across in parallel as well. To check the current (as measured in amps), I would have to break the circuit from battery to the cathode and connect the multimeter in series. Correct?

Yes, but you need you need a low value resistor to provide a voltage for the the meter to read if using volts range. That voltage is indicative of the current flow and will be proportional the amount of current. By keeping the resistor value low, the effect of that added resistance will be small. However a small resistor with small current will provide a small voltage to measure.

If you have a current measuring capability with the appropriate range the resistor is not needed(connect the meter in series).

[ATTACH]23180[/ATTACH]

The circle with +,- are the places to connect the meter/resistor to measure each current. The polarity(+/-) should be as indicated, but ignore the one next to the meter leads(I drew that one bass-ackwards(sorry fer the confusion).

Hope this is not adding to your struggles with an unfamiliar subject.

[heathicus]

OK, things are starting to click now! I'm a visual learner which was why I have a hard time understanding electricity - I can't see it. But with that drawing, things that were said multiple times in above posts are suddenly making sense. I think.

So with a setup like above, I could use a single power source - battery charger and battery - to power all three tanks with a common voltage. Current (amps) would be adjusted by adjusting the anode and cathode - distance between them, amount submerged, or a combination of the two. My multimeter (which does have the capability to measure amps; it has a DC 10A setting and a DC mA setting) can be used to set it to the current we want to test.

One power source, one voltage, three tanks, three current levels. Right?

[JPG]

OK, things are starting to click now! I'm a visual learner which was why I have a hard time understanding electricity - I can't see it. But with that drawing, things that were said multiple times in above posts are suddenly making sense. I think.

So with a setup like above, I could use a single power source - battery charger and battery - to power all three tanks with a common voltage. Current (amps) would be adjusted by adjusting the anode and cathode - distance between them, amount submerged, or a combination of the two. My multimeter (which does have the capability to measure amps]

One power source, one voltage, three tanks, three current levels. Right?

BINGO!!!!!!!!!!!!!!

Three indentical(as near as can be) test parts(rusty rbar).

Three identical sacrificial parts(round is good).*

To vary the current by depth of submersion, do NOT change the test part. Only change the sacrifical part.

Making the test parts different depth violates the 'all three the same except voltage' requirement for the test pieces.

Good you will not need that resistor!



One 'final' concern. When he got 'approval' for this, did he state 'his' hypothesis? If so, the common voltage violates it. If so, adjusting the current violates it. His should only alter the voltage applied to each test piece setup.

However this setup will confirm 'your' hypothesis.(and 'our' common thinking) It will also provide different results for each test piece.(if stopped in time;))

* The sacrificial pieces do not need to be identical(shape/area) since they will be used to provide the current differences. Their area could also be varied.(variable submersion does that!)

I do hope he can/does alter his hypothesis!!!!!!

[heathicus]

He did not state his hypothesis when he got approval. To get approval, he just had to list the requirements (materials) of the project. And honestly, I wouldn't be surprised if his teacher didn't even understand it. I'm not just bragging when I say he's the smartest kid in that school and possibly even the smartest person. That's not to say he knows everything, but when he decides to learn something, he learns EVERYTHING about it.

[heathicus]

I'm still waiting on him to wake up so we can discuss the project. But I'm currently feeling confident in my understanding to explain it all to him. Thanks to you all for that!

If he doesn't get up soon I'm going to have to wake him up and potentially suffer the wrath of a prematurely awoken teenager! But time is short and we're burning daylight...

[heathicus]

He's up, we talked, he understood everything in about 3 minutes that it has taken me 3 days to figure out. Then he reminded me of the only rules that were given:

No live animals
No open flame
No batteries larger than a D cell.

(He still doesn't know if that is larger in physical size, or larger in output, but was told he could use multiple Ds.)

[BuckeyeDennis]

He's up, we talked, he understood everything in about 3 minutes that it has taken me 3 days to figure out. Then he reminded me of the only rules that were given:

No live animals
No open flame
No batteries larger than a D cell.

(He still doesn't know if that is larger in physical size, or larger in output, but was told he could use multiple Ds.)

An alkaline D cell can supply 1A for about 5 hours, and the voltage will decline from 1.5V to 0.8V while discharging. You would need 8 of them in series to get the initial 12V. So the wall wart is looking pretty good in comparison.

How about the PC power supply option?

[JPG]

He's up, we talked, he understood everything in about 3 minutes that it has taken me 3 days to figure out. Then he reminded me of the only rules that were given:

No live animals
No open flame
No batteries larger than a D cell.

(He still doesn't know if that is larger in physical size, or larger in output, but was told he could use multiple Ds.)

That will 'slow things down!'

Hate to say this, but, batteries could be provide different voltages(different series stack for each test). But IMHO that really introduces additional uncontrolled variability(available 'stuff' from different batteries)

[JPG]

With the minimalist power source, keep the test parts small. i.e. keep the area submerged small so the available current will do it's duty over a smaller area and thus be more discernable.

We know the charger/battery will work. We do not know the d cell effect. You will need to experiment re electrode sizes etc. to determine if enough current will flow to do any good! Do that experimenting on a fourth piece of rbar.