Newbie question about step down voltage

If you don't care about the energy cost and if the current through your material is constant, you can put a resistor in series. Not very elegant, but very easy. Multiple diodes would also work (use them in pairs to allow both current directions) and they are more stable in terms of voltage drop.

 

The resistor should be rated for the expected power value and have the right resistance value of course, everything else does not matter. It also does not matter on which side you put it into the circuit.

The rods are connected to your power supply. And the water connection is like a resistor as well.

 

The resistor is always in series with the cell, so it will always reduce the voltage applied to the cell. Resistors do not care about the direction of current.

It does not make sense to say "the polarity switches to this side" - the voltage is always applied between the two sides, so everything that changes is the direction of current and voltage.

 

It won't act as a fixed voltage limit, but it will always reduce the voltage applied to your cell, independent of the current direction.

Then something else is wrong.

 

Dividing your resistance into 2 separate resistors will make not a jot of difference in a series circuit like this.

I suspect the timer switching every 2 minutes may have been implemented with DC in mind? It will achieve nothing different to were it not present when you are using AC. What is your source of 12V AC?

What do you dissolve in the water to make it conductive before hanging the rods in it?

Do you have a web link to point to where you are following some instructions?

 

That does not make sense.

Please show a sketch of your setup.

There is no "3V resistor". The voltage drop at the resistor will depend on the current. Which current do you have in your setup?

 

And the outcome being that after some hours you end up with a tiny pile of silver "dust" under one rod? Is that it? While your reversing timer may well evenly share the effort between the rods, you may just end up getting half as much silver from each, so no net gain? Was this something you devised, or is it standard recommended practice? Does one rod liberate a white fog of miniscule bubbles into the water---if so, then indeed periodic reversal is a good technique.

The best way to drop the voltage from 12.3V to 9V here is not with a resistor, but with a couple of rectifier diodes. You'll need 4 or 5 diodes, the type you would buy to make a low voltage power supply. Rated at 50V or 100V and 1 amp will be good and robust. Connect them in series, and place them in one of the leads where polarity does not reverse. Measure the voltage across the silver rods to see how close to 9V it becomes. Each diode loses about 0.7V at low current. These are better than a resistor here.

Can you explain how you concluded that it will perform better with 9V? What probem are you seeing the 12.3V cause?

 

Back in post #2 in this thread, mfb pointed out you can pair each diode with a parallel one that's reversed then it will conduct in both directions, showing 0.7v drop regardless of current reversals. So you need 8 to 10 diodes now. Almost any sort will do, I just recommended power diodes because they have stronger leads and are more likely to survive an accidental touching of the silver rods! Open up the power supply from a junked VCR or desktop computer box and you'll see big diodes you can carefully salvage using a pair of sidecutters. (First short out big capacitors in case they have held a charge, if recently used. Make sure it's unplugged from the mains!!) Don't bother trying to straighten out the leads of diode you salvage, more bending can weaken them. Just solder them into two strings, one going one way, the other in the reverse. Good luck!

We'll recognize you as the blue-skinned guy who doesn't suffer from winter colds & flu??

 

Have you tried hanging 6 or 7 rods in the one jar and powering all in series? Use something inert to keep them from touching, and I think you'll put 3 times as much silver in solution for no extra time or effort. The 12.3v may be a perfect match for half a dozen rods!

You didn't answer my Q as to whether in operation a stream of white gas can be seen drifting away from either electrode?