Oxidation problem of copper strips in ESL

[chinsettawong]

Hello,

I recently found a problem with my ESL. The copper strips which I put around the ESL for biasing the diaphragm turn green and do not conduct very well. Indeed the climate in my country is very humid. What should I do to prevent this oxidation?

Wachara C.

[geraldfryjr]

I had given that problem some consideration when I built mine 7 years ago and decide to use aluminium foil tape.
They still work today and no corrosion problems have ever occured.
Resistance factor?
At an esl's voltages, it isn't going to make a bit of diffirence.

[chinsettawong]

Hi Jer,

Thanks for your advice. I've never thought of that. Maybe that's what I should do. The attached picture shows how serious my problem is.



Wachara C.

[geraldfryjr]

I like your stator material can give me the dimensions of the holes and such,I like the looks of hexagons better than circles and I think it would allow a more consistant thicker coating without closing them up as much.
I also had this in mind, that if I were to use copper, was to get a home gold plating kit to coat the copper with.
Maybe you could do that instead of having to tear everything apart.
Or if you do choose to redo everything the gold coating will not corrode and you can still easily solder to it, something you can't due too well with aluminium.
I was thinking of doing this to my tig wire stators before I clear coat them as copper is pretty but gold would be better with the added benifit of anticorrosion. jer

p.s. sodium hydroxide (lye) will clean that copper to a super bright finnish without etching or disolving it.

[vmk]

Sorry to hear about your problem with the copper, sometimes it seems that you really need a long fuse with these ESL's.

You could maybe try leaf gold? Might be tricky to contact to HV-supply though, but if you use foam tape and connect that to some sort of a terminal it might work. Don't really have any experience with that stuff, but I know it's pretty thin...

[geraldfryjr]

vmk,if that is real gold I would like to find a supplier here in the states.
I had found that web site a long while ago and the only true metal leaf I can get is pure copper or aluminium in sheet form.
It would be nice to get some of those 6mm rolls for some diy ribbons. jer

[chinsettawong]

Hi Jer,

The hexagon stators certainly look nice. But they might not have the hole size that you like to have. Here in Thailand, the smallest hole I can find is 6 mm and I think the holes are too big and the open area is too much. The efficiency is therefore quite low. I now have to use 9.6KV of bias voltage for my panel with 3 mm spacer to sound loud enough for me. I use 1:150 transformers and a 300 watts class D amp.

I'm thinking of using black ink to draw a line for biasing diaphragm instead of using copper. In my experiment, the conductivity is not too bad with this ink. What do you think?



Wachara C.

[mavric]

would it be wise to clear coat the copper ? or will that lock in moisture and deteriate anyway, or just keep an eye and keep em clean? never thought about that untill i saw the pics. Mav

[chinsettawong]

Hi Mavric,

The problem is that you need to make the copper conductive. With clear coating, of course you can prevent the oxidation problem, but there won't be conductivity on the copper to bias the diaphragm.

Since you are making your new ESL, why not take this problem into your consideration and choose a nice and long lasting material for this purpose? Let's think about it.

Wachara C.

[mavric]

10-4, i have allready purchased the copper and was looking for a way to protect it, lithium grease,, something to coat copper with no adverse effects.
so YES, lets think about it. i have not apllied mine yet, so this will be good info for anyone reading.