Power Supply for Electrolysis

[Rick_B]

Free is perfect! I just wouldn't run out and buy a switching power supply for plating. PC supplies are plentiful and disposable. I approve of it in this case, there's nothing to lose and good insight to be gained.

If you were building it for a "customer", I'd get the *correct* power supply, but if you're still experimenting, then by all means! Put that PS on a power strip or other line protection with a 15a breaker, just in case the caps or the transistors don't like the salt bath load.

pontiac 428 - what is a "switching" power supply?
Rick

 

[Rick_B]

It'd still be expensive for a pipe in particular, but I've had more than one occasion where instead of a "container", it was cheaper to buy a "barely big enough" PVC pipe, and a cap, to make a "deep and skinny bucket". Never kept one long enough to know if it'd be an heirloom piece, but they work well for the amount I've ever used one. if you WANTED to use evaporust.... You could probably double cap a "displacer" piece of pipe on the inside to get rid of a bulk of the inside space within the workpiece that way. I know that's not what you're asking about, just throwing it out there.

On your electrolysis- Amps really aren't that relavent, WITHIN REASON. You can do a plenty good job with a two or three amp phone charger (you'll need to cut the USB end off of it.....) Another strong option is the old school, metal case, non safetyfied, "everybody used to have one" 10/2 amp, 6/12 volt battery chargers. The six volt, 2 amp setting is solid to just set and forget. If you go to a larger charger that doesn't have such a low setting, you'd have to measure it initially into clean water, but you can easily set that to "reasonable" simply by using the crudest guage (like built into most chargers) to control the electrolyte concentration. Amps and volts are gonna do their own thing and settle in where they want to be, but setting that up to just a couple of amps to begin with means it'll sit quiet and happy for you as it does it's thing.

I suspect you're going to find this is not going to be an overnight "set and forget" project with electrolysis. The inside and outside surface of the tube may well give you fits about preferential current paths, and need (or at least want, in terms of time to completion) some readjustment of the annodes as the project moves along.

I was wondering about that Jake - I've read that electrolysis is a line of sight type process so maybe I would need to lay it down suspended in a trough or as you said adjust anodes
Rick

 

[pontiac428]

pontiac 428 - what is a "switching" power supply?
Rick

Rick, there are two main types of AC/DC power supply, transformer and switching. Transformers have been around forever and obey all the classical rules. Switching supplies are newer, because they required the invention of high amperage, high speed transistors to react to changes in the line. They more or less work by "chopping" up the AC wave in timed pieces and rectifies that into DC PWM. They are electronically controlled on closed-loop feedback. Because the output is PWM generated and not a true constant supply, they can cause all kinds of problems in classical analogue circuits under certain conditions (welders used to be one example of incompatible systems, but they aren't a problem anymore as tech caught up) . The big caveat is that the most recent switching power supply tech is very good (if you're willing to pay for it). The gotcha is that the Chinese have a cheap version of that, too.

 

[Rick_B]

Rick, there are two main types of AC/DC power supply, transformer and switching. Transformers have been around forever and obey all the classical rules. Switching supplies are newer, because they required the invention of high amperage, high speed transistors to react to changes in the line. They more or less work by "chopping" up the AC wave in timed pieces and rectifies that into DC PWM. They are electronically controlled on closed-loop feedback. Because the output is PWM generated and not a true constant supply, they can cause all kinds of problems in classical analogue circuits under certain conditions (welders used to be one example of incompatible systems, but they aren't a problem anymore as tech caught up) . The big caveat is that the most recent switching power supply tech is very good (if you're willing to pay for it). The gotcha is that the Chinese have a cheap version of that, too.

Gotcha Thanks
Rick

 

[Rick_B]

So let's assume i get a power supply - picture a drill press column but 6" in diameter and 28" long and I want to subject it to electrolysis to clean up both the OD and ID. I was thinking of using a plastic trash barrel and standing it up but that doesn't seem to give the "line of sight" requirement. I think I might be better off laying it horizontal? Any thoughts?

Rick

 

[pontiac428]

In practice, it takes more than that. In the simplest sense it is a line-of-sight process, but Gauss proved that to be a little more complicated.

You will need to run a rod, wire, some kind of cathode inside of the tube. In a coaxial arrangement, the electric flux is radial, and given enough current density-time, will work. It won't matter how it is oriented, except for the bubbles acting as insulators. You can also make a cannon swab, wrap some wire around the end, clip your electrode to the wire, the other to the pipe, dip it in electrolyte, and wipe the rust out. Electrobrushing is a thing.

 

[ErichKeane]

Yep Ed nailed it again- something like this would work fine for small projects:
I don't know how much current you need- for tens of amps the one you linked would be cheaper than building it
You can add an external ammeter to any supply you buy; be sure it is an internal shunt type-more convenient
Some ammeters require an external shunt for measuring larger currents (more than 20 amps)

View attachment 447406

I might suggest putting a filter capacitor across the output terminals of the bridge rectifier. I would think a 'smoother' DC power supply would be better than one that keeps going to 0.

 

[graham-xrf]

@Rick_B Hi there
Have a look at another posting earlier today on this site
--> https://www.hobby-machinist.com/threads/homemade-nickel-plating-with-coins.106191/

It is a great convenience to have a variable voltage settable supply, as used by electronics hobbyists. Especially those which can have a current limit which you set by giving it a short-circuit, and then setting the knob. You can then turn up the voltage until the current limits, add on a little, and leave it to carry on plating.

Putting a whole 12V from a supply capable of delivering a big current without collapsing (20A) made a big mess. You can "turn up the current" to some amps, say 2A to 4A or so, if you are de-rusting. For electroplating or anodizing, then much more finesse is required.

You are clearly into bigger stuff, and it may have much more area, in which case, by all means, use more current. You know you have gone too far if the bubbles are forming too intensely. A thing as big as a drill press column might be better tackled by the method mentioned by @pontiac428. It's easier to say than to do. I used a big rag, and an old battery charger croc-clip, and I kept dunking it. I had used a little diluted battery acid to get the water conductive. This, by itself, somewhat cuts into the rust. I chose sulfuric over hydrochloric because I did not fancy chlorine gassing off. Also, stuff containing sulfur is not such a danger to the environment. You can pour it onto the ground.

To limit the amount of fluid I needed, even on the smaller parts I was involved with, I resorted to a plastic guttering down-pipe, with a wide slit cut along it's length big enough to admit the part. I blocked the ends with salvaged plastic ends as used on cardboard shipping tubes cut to fit, and glued on with hot-melt.

Here is a picture of a gash knocked up plating bath I tried back in 2021 to rust-proof a lathe spindle.

 

[pontiac428]

On the subject of plating, did you notice that @celsoari glaringly did not use a copper strike coat before nickel? I was surprised it worked at all.

 

[Nesse1]

I've got a cheap china made variable output power supply I use for my zinc plating kit. Having the ability to vary the current is a huge plus. As mentioned earlier in the thread, turn up the current until bubbles come off the part, and then sit back. I've also read that areas with line of site to the electrodes get better results. I've done the electrolysis thing before, but I prefer phosphoric or oxalic acid. It's cheap and works great.