HV connections

General discussion of laser machines

HV connections

Postby pixpop » Fri Dec 18, 2009 7:50 pm

Hi, I'm new here. Just getting back into a project that I put on hold a couple of years ago.

My current question is: What's the best method for attaching HV leads to the electrodes of the laser tube?
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Re: HV connections

Postby bdring » Sat Dec 19, 2009 12:30 am

Hey pixpop...welcome to the forum,

I would have loved to have had a magic solution, like a connector thingy, but here is what I did. The electrode on the tube was a stiff, small dia. rod. The HV wire was also quite stiff. I read that soldering was bad and could compromise the seal, so I avoided that. I put the HV wire along the electrode so both were in parallel. I then took the smallest gauge bare wire I could find (like 36awg) and "lashed" the two together. I then covered the connection with silicone fusing tape. This stuff is great. It is excellent for HV and makes a high strength seal.

I hope your tube is still good. I hear they don't have the best shelf life.

Keep us posted on you progress.

http://www.rescuetape.com
self_fuse_tape.jpg
self_fuse_tape.jpg (10.08 KiB) Viewed 11106 times
Bart
"If you didn't build it, you will never own it."
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Re: HV connections

Postby pixpop » Sat Dec 19, 2009 4:09 pm

I did find a connector that I think will work, but haven't tried it yet. I'll post some pictures of it. I wanted a connector so it would be easier to disconnect & reconnect tubes.

I like the fusing tape idea. Never heard of that before. I'm going to get some and experiment.

I'm not worried about the tube. I bought it too soon, before I was ready for it. At the time I was unaware of the limited shelf life issue. It's only a 15 Watt tube, so no big loss. Maybe it will work well enough to test my power supply.

A poster on CNCZone indicated that it is OK to use a power resistor as a dummy load for testing, so that's also useful info. He shows a picture of a 200K wire wound resistor that was recommended in place of an 80 Watt tube.

See here: http://www.cnczone.com/forums/showthread.php?t=95634

Thanks for the info.
pixpop
 
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Re: HV connections

Postby pixpop » Sat Dec 19, 2009 5:11 pm

Here's the connector I was planning to use, unless I find something better:
Image

It's quite high quality. Both ends are open. The side with the little hole is for the wire. The other side is meant to grab onto a metal post sticking out of a circuit board. It has phosphor-bronze metal fingers inside that actively clamp onto the post. It's a crimp termination for the wire, but I would probably solder it.

Image
About to connect...

Image
This is the point where the fingers inside just begin to grip. At this point, it will no longer fall off if you tip it upside down.

Image
Here it is seated all the way down. At this point it is quite a strong bond, and will not come loose accidentally.


The connector is made by Mill-Max, and their part number is:
0368-0-33-01-13-27-10-0

I obtained them from Mouser. The Mouser part number is 575-036800

Here's the data sheet. It shows other connectors that might work as well.
http://www.mill-max.com/images/products/pdf/159N.pdf

Of course I have no idea how this will stand up to repeated temperature cycles, but I expect it will be OK.
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Re: HV connections

Postby bdring » Sat Dec 19, 2009 7:45 pm

The connector looks good. I have a lot of MILL_MAX connectors, but they were all a little small. That sounds perfect.

It sounds like you have a plan for the load. We use power loads at work for our HV stuff. Laser tubes usually have a start voltage and a run voltage so I did not want to guess at an appropriate load. They must fire all power supplies up at the factory on a load, so it will probably work.
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