[CLOSED] Starting gas for a pretty good price

Re: [Renewed feeler]Starting gas for a pretty good price.

Sigurthr said:

Yup, $10-15 of parts in it, yet it costs >$100 used!

I think our sentiment is probably shared by many other EEs out there though.

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Do you have a schematic? I might give it a shot if it's that simple.

Re: [Renewed feeler]Starting gas for a pretty good price.

There are several on Sam's Laser FAQs. you might try there first.

Re: [Renewed feeler]Starting gas for a pretty good price.

Atomicrox said:

Do you have a schematic? I might give it a shot if it's that simple.

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yeah I built one a long time ago. cost me about 30 bucks. but it wasn't quite as good or as reliable as an official one. but the price difference was definitely staggering compared to the same thing being $75 from MI.

Re: [Renewed feeler]Starting gas for a pretty good price.

There's several on Sams, but you can also do a standard constant current boost converter, a standard inverter and step up transformer followed by a rectifier and filter, etc. For the igniter you can go the pulse transformer route or my personal favorite RF ignition.

I'm quite fond of the flyback method too as the open circuit voltage will be enough to ignite the tube, and then once the arc is established the closed circuit voltage falls to normal ranges. You just need to adjust the PRF to achieve the current you are looking for with the RC filter to limit current and prevent arc extinguishing. It's basically a CV supply that uses a fixed series resistance to deliver CC. If the voltage isn't allowed to change then the current can't change either. The trick is in the logic to allow for an ignition voltage higher than the set point voltage, but that's not hard to do; just run a current sense resistor and when that is lower than the reference just disable the voltage feedback circuit. So basically you need a VCO, a FET driver, a FET, and two comparators for the entire active section. A few resistors, a HV cap, and a standard LOPT will complete the unit.

Btw, you can run HeNes on RF or even AC, but it degrades the electrodes unless it was designed for it. I once ran a large HeNe off of one of my SSTCs.

Re: [Renewed feeler]Starting gas for a pretty good price.

Interesting, thanks for the heads up! Will take a look at Sam's when I get some free time.

Re: [Renewed feeler]Starting gas for a pretty good price.

You say smaller then the one in that photo... But how small are they? As that one is pretty small! I wanted to get an open tube like the one in your photo to make a table lamp out of. Would these be to small for that?

Re: [Renewed feeler]Starting gas for a pretty good price.

Yep they're 6" long. like the ones in my avatar and tiny HeNe laser thread.

but rather than being flat metal endcap style, they are bell style tubes like my P122 in that thread above, which is about 9" long. If you want a slightly larger one, I also have a uniphase for sale in my B/S/T thread that is also new, but about 10" but the smaller diameter as well (pics in that same thread in fact) that is for sale for a bit more. just depends on what you want it to look like. these tubes are awesome for lamps, they're very tiny and lightweight and the beam is easily dealt with for that.

Re: [Renewed feeler]Starting gas for a pretty good price.

I would like 1 tube + psu please

Interested in seeing what I can accomplish with this little guy, as well as the other small one I've got that I will now be able to power

Re: [Renewed feeler]Starting gas for a pretty good price.

Sure thing bloom

Re: [Renewed feeler]Starting gas for a pretty good price.

Vortish just got a new He-Ne laser that is the cutest thing I've ever seen. It is in just like new condition with PSU and manual. I bought it for him, so don't think that he's spending his own money on this. I am about to ship it out to him, so I'm sure once he gets it he will post pictures of this awesome little laser.

Re: [Renewed feeler]Starting gas for a pretty good price.

Yes and I was a very nice thing for you to do. I personally love my little 6" orange

Re: [Renewed feeler]Starting gas for a pretty good price.

I assume I'm still in for one of these. I didn't talk about payment to get an atta boy, just wanted people to know that he didn't spend the money donated to his family for this purpose. It was my decision and I was glad to do it. Wait 'til you see this cute little thing! It is immaculate and looks like it was built yesterday. Laser, PSU and manual all together.

Re: [Renewed feeler]Starting gas for a pretty good price.

I meant to ask this last time I saw this thread bumped but how much plasma do these tubes show? I have one small bare tube red but there's only maybe an inch of actual bare tube.

Re: [Renewed feeler]Starting gas for a pretty good price.

Yeah they're fun little lasers. But still you went above and beyond, and that deserves some recognition.

Re: [Renewed feeler]Starting gas for a pretty good price.

Can I get in on this? I would like the tube + PSU + wallwart please. If you have stands, too, that would be great. Thanks!

Re: [Renewed feeler]Starting gas for a pretty good price.

No problem.