| --- Mon Nov 12 2012 | 00:00 | |
| Sync | bah still unsure what is the easiest and cost effective way to make vacuum chambers | 19:42 |
|---|---|---|
| Sync | favoring a brazed Al construction now | 19:43 |
| berndj | you building your own vacuum chamber? | 22:03 |
| Sync | yeah still on it | 22:04 |
| Sync | I need several too | 22:04 |
| berndj | pumps? | 22:04 |
| Sync | I have most types of pumps that are commonly used | 22:05 |
| berndj | what motivates against stainless steel? | 22:06 |
| Sync | the cost | 22:06 |
| berndj | they cost the same at my local scrap yard | 22:07 |
| Sync | I currently cannot weld Al which is annoying so I have to braze or oxyweld it | 22:07 |
| Sync | yes but I'm not going to use scrap metal | 22:07 |
| berndj | fair enough :) | 22:07 |
| Sync | (only because my local scrapyard does not have stainless in sizes I want) | 22:08 |
| berndj | can you TIG at all, or just not do it to aluminium, or not at all? | 22:09 |
| Sync | I do have a TIG welder | 22:09 |
| berndj | cheap one / fancy one? | 22:10 |
| Sync | it is a chinese one but it works reasonably well | 22:10 |
| Sync | but I almost finished my ac tig inverter | 22:10 |
| berndj | same here, but mine can only output DC, so probably can't do aluminium | 22:11 |
| Sync | I just need some better mosfets in the bridge to keep the losses low | 22:11 |
| Sync | you can do Al with a regular dc tig welder | 22:11 |
| berndj | i've been back-of-the-enveloping a diy welder too | 22:11 |
| berndj | i can't get it to work out cheaper than buying one :( | 22:11 |
| Sync | you just have to use DCEP and preferrably Ar/He mix | 22:11 |
| berndj | oh right, the DCEP trick | 22:12 |
| Sync | oh it was cheaper for me than buying one | 22:12 |
| berndj | with a giant fat tungsten electrode so you can just barely weld the thinnest sheet! | 22:12 |
| berndj | so, out with it then, what mosfets? | 22:12 |
| berndj | beefiest i've been able to find so far are IRF*2907* | 22:13 |
| berndj | * cost-effectively-beefiest | 22:13 |
| Sync | the 2907 have too low Vdss to have a good safety margin | 22:14 |
| Sync | I have FDH055N15A | 22:14 |
| berndj | i'm tempted to build an H bridge to chop up the DC output from my welder, but i don't know the welder well enough to know if it'll get angry about it | 22:14 |
| berndj | what open circuit voltage are you working at? | 22:14 |
| Sync | actually, I have not measured it | 22:15 |
| Sync | but it is around 60V iirc | 22:15 |
| berndj | mine hovers at about 75V | 22:15 |
| Sync | then your fets will be no good | 22:15 |
| berndj | dunno what limits it | 22:15 |
| berndj | yeah, 2907 is 75V i see now | 22:16 |
| Sync | I also have some IPW65R037C6 for the primary converter | 22:16 |
| Sync | the most costly semi in the thing is the SiC diode in the PFC | 22:18 |
| Sync | I currently combat some strange transients that kill my primary fets | 22:20 |
| berndj | oh and what's your capacitor bank like? | 22:24 |
| berndj | the caps i can find don't really seem up to the ripple current required | 22:25 |
| Sync | I don't have many caps in there | 22:35 |
| --- Tue Nov 13 2012 | 00:00 | |
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