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magnetomotive

Sun Jul 26 2009, 07:58AM

Registered Member #267 Joined: Mon Feb 27 2006, 09:44PM
Location:
Posts: 46

Arcstarter wrote ...

Yea, some of them look cold, but i assure you they are not. I heat most joints for about 2-3 seconds after i melted them, after flowing. The blur is pretty bad, and the solder i am using is not great, i dont think. I got some different solder made for electrical connections and it shines much more. It flows a bit easier. I am think my dad got the wrong stuff, which is weird. The flux also sometimes leaves that brown/black crap on the top of the joints occasionally, but i could wipe that up.

Your dad probably got acid core flux (as opposed to rosin core flux). Acid core flux is meant for pipes or other metals that are very dirty. Or maybe its lead free solder, which is more difficult to solder with.

Steve Conner

Sun Jul 26 2009, 10:19AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

hvguy wrote ...

Ya, carb cleaner is great stuff, it's like the duck tape of solvents, looks great shot through a lighter too

Just don't look at the MSDS

whatever you do! If it contains methylene chloride, you get all sorts of toxic compounds when you burn it.

hvguy

Wed Jul 29 2009, 07:45AM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

It's quit the chemo-cocktail, almost as bad as burning PVC in an enclosed room

It might also be useful to point out how horrifically bad solder flux (and leaded solder) is for you. I spent far to many years inhaling solder fumes, I use a filter system now and would highly recommend them to everyone.

Arcstarter

Sat Aug 15 2009, 09:52PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Well, some progress has been made.

I made the halfbridge with the Semikron superfast IGBT. It does not look good, but there is nothing that should cause any bad operation... I hope.

I also finished the driver board, just about. Just need the 15v regulator and the filter capacitor for it. There are about 6 decoupling capacitors along the 15v rail, and probably 2-3 on the 5v rail. I used a SMD capacitor too, which look like crap. But, it's fine. I also need to get a new jack for the interrupter, someone threw mine away.

The last picture is the bridge output wire, that goes to the capacitor. It was lietz that is around 5x 12 gauge. I separated the 5 bunches of wires, stripped the insulation by heat and dremel, and tried to place the bunches of wires perfectly horizontal. I cleaned, roughened, and fluxed the copper. I heated the two with a pencil torch, and melted the solder. It did not work well, because the wires when not aligned right, so i had to push them down with a drill bit, and it just all kind of went to hell after that

. It is continuous, though.

1250373156 1225 FT72509 Drsstc Driver2 001

1250373156 1225 FT72509 Drsstc Driver2 002

1250373156 1225 FT72509 Drsstc Driver2 003

teslacoolguy

Sun Aug 16 2009, 01:17AM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

Hmm, that looks pretty good but i think it could be better. The snubber cap should be extremely close to the bridge at all possibilities and with same length leads. The snubber lead inductance puts all kinds of nasty spikes in your switching waveform that can kill your igbt. Also i dont think you need 10uF, i would start with as little as 2uF and look at your switching waveform to see how bad the ringing is. I also see some 10/12G ring terminals that look to be going to a future bus cap. I highly suggest you use aluminum or (even better, copper) bus bar between bus cap and igbt and as always keep everything extremely short.

hvguy

Sun Aug 16 2009, 06:03AM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

Ya, I completely agree here. You need bus bar or large wire (8ga at least) going to your DC buss cap. This cap is your real source of power for the pulse, not the small bypass cap. Copper bus as short as possible would be ideal. The rest looks good...

Arcstarter

Sun Aug 16 2009, 03:12PM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

Well, i simply cannot find copper strapping, and i do not think i will have any extra copper pipe to flatten out. Remember? This is a 40$ drsstc. I have not even spent the money yet, so far it is free (other than the trades).

It is not going to get any better until i can get some money. And regarding the snubber cap, i cannot think of any way to mount it *any* closer with anything i have. I am sure i could solder a longer lead to the existing lead, but that would be worse than the copper strapping. It would have to be just as long. Any ideas? Help me out here guys :P

It is the only suitable capacitor i have for snubber. Also, why use 2uf and then go up? Extra will not hurt, and it'd be easier to get it on the first try.

If i get 2 foot sparks i will be pretty satisfied. Nothing but a couple trades, and no money spent. Though, this being the case i am not spending a ton of time on making it look good and be all perfect, which may come back to haunt me...

Edit: I will use some very thick lietz, if that is any better. Or, this normal copper wire that is about as thick as the lietz, which i would prefer...

Another edit:

The snubber cap should be extremely close to the bridge at all possibilities and with same length leads.

Of course i agree, but i am thinking it is not too far to cause problems? One of the leads is less than an inch from the terminal, and the other is about 2 or so inches. However, it is thick so resistance is not a problem, but would it be too much inductance?

hvguy

Mon Aug 17 2009, 04:48AM

Registered Member #289 Joined: Mon Mar 06 2006, 10:45AM
Location: Conroe, TX
Posts: 154

Don't worry about the snubber cap, it will work where it is, it's just not ideal. Use anything to connect your bus cap, it should only be 2" or so which is not a significant resistance/impedance. Some 8ga would be fine, but don't you have a new neighborhood or store being built somewhere around you? You can always raid the construction dumpsters for short lengths of copper pipe... or you can PM me for some strap.

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