PSU calculations

[kickn]

Okay - thanks for that - sorry if this is going to frustrate you but what do you think of these:

I know the voltage isn't variable but I thought it was the amps which impact how quickly the layer is created and volts is the possible depth of the layer?
http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=3836386869

a bit overkill
http://cgi.ebay.co.uk/ws/eBayISAPI.d...tem=3836557270

What I want to avoid if possible is getting say a 2.5A psu that takes 4 hours to anodise the part with. I don't have 16hours per unit to spend

I completely appreciate what your saying though about time and money. Unfortunately I have more time then money right now LOL

[Fibergeek]

Neither of those is suitable; the first one is an AC/DC type, the wrong kind for this. the second won't go over 8V, which is too low.

Wait a few days and look again. Or look at the for sale adds in your local newspaper. You'll find what you like, be patient.

[kickn]

Thanks fibregeek - I think my confusion is coming from not fully understanding the requirements. Is 12v the absolute target? or is there a range of say 10v to 14v?

The reason I put the one with only a current control in there was because I thought that it was the current you adjusted and monitored?

So what does varing the voltage impact? I think I understand how the current is working (in a very basic sense anyways).

If I did want to anodise all 4 parts at once (for time) then I would need a 14v 30a psu right? I know there are cooling issues but I would of course deal with that.

Thanks again

EDIT:

Okay - i'm working out the forumlas based on LCD right now to get a good handle on things so please ignore the rather stupid statements above.

Can you tell me how though you work out the potential voltage required? I can see how to work out the amps but as I see it PAR will increase and then decrease - is there a way to formulate the potential maximum? or is this just based on tests?

Just on the psu front how about this one:

http://cgi.ebay.co.uk/ws/eBayISAPI.d...e=STRK:MEWA:IT

I'm still looking around

Thanks

J

[Fibergeek]

A power supply like that one is what you want.

We determined at the start of this thread that you needed a minimum of 27.4A to anodize 4.56 sq.ft. at 6ASF. This corresponds to a maximum Voltage of 13.2V. We also agreed that you should have some margin, so we bumped up the maximum Voltage to about 15V. This will require 27.4A x 15V = 411W. This is going to get expensive.

We then agreed that a reasonable compromise would be to do the anodizations 1 piece at a time. Since the largest piece is 1.98 sq.ft. the power requirements are now 11.9A and 15V, which is 11.9A x 15V = 179W. This will cost less.

If you had a 10A power supply, you would need to reduce the current density to 6 ASF x 10A / 11.9A = 5 ASF. 5 ASF is within the LCD range so this will be OK.

When all of this makes sense to you; and you understand how to adjust the process without getting into trouble, you can optimize it to suit your particular application. At this point, you can make the necessary process adjustments to speed it up considerably, and you will know how. Or maybe you will decide that that it will be too expensive and you will live with the anodization time. Either way you will be successful.

[kickn]

Well - i just won the auction - a bit more then I would have wanted to spend but if it gets things going then hey!

My gameplan is to get this going with single pcs in a reasonable timescale and then move from there into 4 pcs (by wich I should have gotten around to buying/building a bigger supply)

I have a good idea now of how things are working - thanks for all your help

One question I do have though is how to calculate the potential max voltage. I was reading the manual but I think I was missing something.

By my numbers this should take about 70mins @ ASF 5 right?

Am I also correct in my understanding that the electrolite solution is 5% solphuric by volume?

[Fibergeek]

Good for you.

5 ASF would require 72 minutes, 70 is close enough.

The easiest and cheapest way to make LCD electrolyte is a mixture 1 part commercial battery acid to 3 parts distilled water by volume. You add the acid to the water and not the reverse of course.

[kickn]

If you can tell me the percentage it would help as I already have a couple litres of 98% sulphuric acid here Thanks!

[Fibergeek]

I copy and pasted this from one of the stickys at the top, you should read these when you get the chance.


Concentrated sulfuric acid; 100% by weight and volume.
Commercial battery acid; 35% by weight, and 19.2% by volume.
"Professional" electrolyte; 16.5% by weight, and 9.4% by volume.
Caswell's 1:2 electrolyte; 6.4% by volume.
LCD electrolyte; 4.8% by volume.

[neilfj]

If you're using 98% sulfuric, there is a slight difference between % by weight and % by volume....but not enough to matter much.

You'd mix about 5 - 5.5 ml of acid to each 100ml of distilled water. This will give you a 4.8 - 5.2% final concentration, which is fine for LCD.

There are methods to determine this exactly, but its really not worth the effort as LCD has a wide range of concentrations in which it will work.

[kickn]

Thanks everyone for your help

I'll give this a shot once I get my new kit and let you know how it goes!

Thanks again!