Melles Griot 561nm Lab laser

ultimatekaiser · Jul 6, 2014

Yeah it is coming with an omni 171B, but no power cord. It'll be arriving like yours: head, supply, and umbilical. but mine will have its keys and interlock. Just need to come up with 220V. My parents only have 110V 15A power receptacles

hwang21 · Jul 6, 2014

You snagged that eBay unit huh? I knew someone would grab it eventually... enjoy it! I was gonna get it but decided not to at the last minute a while back

ultimatekaiser · Jul 6, 2014

Which one? There's a few on ebay.... And this one is actually a university pull. Having a lab upgrade.

Sigurthr · Jul 6, 2014

208V is a pain to accommodate. There are some step up transformers for it, but they're hard to find and tend to be pricey. I know more than a few folks who use 240V step up transformers fed by a variac.

ultimatekaiser · Jul 6, 2014

yeah it says 220VAC on the label. I have a Rockstone step up/down transformer that is supposed to be 5000W, so I think I'll give it a go when it arrives. should come to about 2200W max, so it should handle it. problem is i'm not sure if my house is fused for 15 or 20 A. they're all 15A recepticles, but I'm sure the wire is 12 gauge so it shouldn't be a problem in that area, but if the panel is breakered/fused for 15A (1650W I think) then it might throw them...I may have to look. It's not uncommon to use a 20A fuse and still wire 15A receptacles into the wall. it still passes inspections commonly. I'll have to get with my father and see if the breaker panel is set high or low. if they're 20A fuses/breakers, then it shouldn't be a problem.

Sigurthr · Jul 6, 2014

If they're 15A breakers just parallel up two lines, make sure they're the same phase leg though.

Cyparagon · Jul 7, 2014

Nah, you should be able to run a 15A breaker at 22A for more than 2 minutes before it opens. (source) You should not be running ion lasers balls-to-the-walls anyway. If you need the power for a beam shot or something, 2 minutes is plenty. It seems silly to step-up to 220 when you already have that, but I guess I'm just lazy.

ultimatekaiser · Jul 7, 2014

Yeah I know what you mean cyp. I just want to run it upstairs, and it's the easiest way of doing it there. As for running it at max power, yeah I never do that. My ML uniphase is spec'd at 40mW but can do 120-130mW at max current depending on tube temp. But I always run it @ it's spec 99% of the time to maximize life and gas flow, and keep the temps down. My fan can't keep it cool at max for too long anyway. It's not uncommon for me to run it 20-40mW... Just enough to get all 6 lines in

But anyway, I'm gonna make a thread for it when it comes. Sorry for the thread de-rail, even if it is my own!

Keep an eye out for updates! On both these beasts!

Sigurthr · Jul 7, 2014

208V ≠ 220V. Most 220V appliances will happily run on 240V, which in the US is easily made from two phase 120V (single phase 240V). The two phases of 120V are 180deg out of phase. 208V comes from THREE phase 120V, where phase to phase of any 2 of the 3 phases is 208V. Appliances rated for 208V will not always happily accept 240V. This is often the case where there is an old fashioned stepdown or step up transformer internally that is not regulated, such as a filament supply transformer or B+ transformer. The excess voltage can damage the appliance's electronics.

Anyway I think somewhere above someone said the unit is actually 220V and not 208V, so kinda a moot point, but I didn't want to leave it uncorrected in case someone else was looking to run a 208V item on 240V mains.

Cyp is right about the breakers and Ion lasers though, but you should also keep in mind the wiring in your walls, old aluminium wiring can get quite hot.

ultimatekaiser · Jul 7, 2014

Yeah, it's a fairly new house so it's likely copper. But I might check to be sure.

Cyparagon · Jul 7, 2014

Sigurthr said:
The two phases of 120V are 180deg out of phase.

No, the two taps of US residential power are the same phase. It is single phase power. That is why they "add" together. If it were two phases 180 degrees out, they would cancel.

Sigurthr · Jul 8, 2014

Cyparagon said:
No, the two taps of US residential power are the same phase. It is single phase power. That is why they "add" together. If it were two phases 180 degrees out, they would cancel.

I'm surprised you'd mix up electrical phase mechanics with audio phase mechanics. Audio phases cancel when 180deg out of phase because the ear perceives the additive effect of the waves. In an electrical power draw system the load sees the differential between the phases. When 180deg out of phase the differential is at its maxima. If it were 0deg (in phase) there would be no differential voltage developed and no work would be done. This is the same as having both leads of a two conductor 120V mains appliance connected to the same Hot wire.

Here we see the standard US "240V Split Phase" (120V 2 phase) plotted voltage against time:

Here is the standard US Three Phase Power scheme plotted voltage against time.

Cyparagon · Jul 8, 2014

Yes, with respect to neutral, but that's not how it is used when in 240V configuration. In 240V configuration, it's with respect from one leg to the other. I think we only disagree with terminology and reference points here. Let me use DC as an example:

you: "you get 7.4V with a -3.7V and a +3.7V lithium" (referencing the center of the two as ground, unknown to me)
me: "that would cancel to 0V" (assuming ground is at the end, since that's where we physically put our DMM probe)

If you had one AC source, and put it "in series" with another AC source that was 180 degrees off phase, the second source would always cancel the voltage produced by the first... like two batteries end-to-end. That's where we got tripped up here.

2 phase implies 90 phase difference
split phase implies center tap.

Sigurthr · Jul 8, 2014

Ahh, yup, looks like that's what happened. Sorry for the misunderstanding!

ultimatekaiser · Jul 27, 2014

back on topic...update...got 6mW out of it today. seems to not mind as long as I've got it sinked and let it run for a while in a relatively cool room. the power I get seems to depend mostly on ambient temperature sources, and how long I run it, mounted on various materials.

crazyspaz · Jul 27, 2014

Yea, still though, It's probably worthless, you should just send it to me...

On a more serious note, have you tried getting in contact with MG themselves? Surely they wouldn't mind lending a hand?

Melles Griot 561nm Lab laser

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