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LAN_403

HV Enthusiast

Sun Mar 02 2008, 02:45PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Austin wrote ...

What about this one EVR? i'm trying to download a manual / specifications however im not finding anything... probably because it is so old.

Just ask the seller. If he can't answer it, then at least have him to take a close-up of the controls so you can determine if it has what you want.

Also, be careful of double posts.

wrote ...

R21 is a 3W, 1.6 ohm resistor. Using Ohm's laws, I just did a couple quick calcs and...
The formula for power is E^2 / R sooo
12V^2 = 144 / 1.6 ohms = 90 watts!!! How is that 5W resistor supposed to handle that? I must be missing something or something is wrong.

Yes, something is definitely wrong. The test procedure that is. You simply need to insert a variable DC voltage source across capacitor C31 (i.e. 12V) which is the input to the LM3914 display IC. This will allow you to set the display chip to full scale.

Also, the 1.6 ohm resistor is sized properly.

But instead of telling why, i'll you guys figure that out - so put your thinking hats on!!!

Dan

Austin

Sun Mar 02 2008, 06:29PM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

I am not an electrical engineer but does it have something to do with setting the Overcurrent potentiometer to a low voltage (ie 2.95v = 300amps) for initial tests?

Wirenut

Sun Mar 02 2008, 07:18PM

Registered Member #141 Joined: Sat Feb 11 2006, 01:14PM
Location: Southern California
Posts: 96

Is it because the voltage from the CT is actually low-duty-cycle AC?

HV Enthusiast

Mon Mar 03 2008, 02:40AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Wirenut wrote ...

Is it because the voltage from the CT is actually low-duty-cycle AC?

Yes.

Ultra7

Wed Mar 05 2008, 11:36PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Okay, in looking for the IGBT's, I noticed that you guys bought them all up.
No one has any left unless I want to pay $40+ apiece for them.

Sooooooooo. . . . .

I was looking at these.
HGT1N30N60A4D

I noticed that they are not all that different, accept that the 40 is rated for 200A with a 55 fall time and the 30 is rated at 150A with a 58 fall time.

With the active current limiting board, wouldn't I be able to use them safely or would need a complete overhaul of the system?

HV Enthusiast

Thu Mar 06 2008, 12:26AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

yes, those are fine.

Ultra7

Thu Mar 06 2008, 01:26AM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

Cool, I just bought 6 of them then, that leaves me 2 spares to blow up.
At 10 bux a pop, i figure I'll be able to save some money at least. . . .

Austin

Fri Mar 07 2008, 10:26PM

Registered Member #1169 Joined: Wed Dec 12 2007, 09:16AM
Location: Portland OR
Posts: 251

The secondary is just about done, just need to add a few more coats of the minwax.

This was my first attempt at making a secondary. It turned out alright however leaving it outside over night to dry must have caused the wires to bunch up and overlap just a little. It was very tightly wound and the bumps were not there the night night before.

Has anyone ever experienced this before? Also will these bumps cause a major problem? Below are some pictures of the secondary.

I would also like to thank Anders M. For sending me an extra modulator board. Without the help and support from you guys the construction of this DRSSSTC may not be possible.

Taken after I left it outside to dry

Taken before I put it outside!

...

Fri Mar 07 2008, 11:24PM

Registered Member #56 Joined: Thu Feb 09 2006, 05:02AM
Location: Southern Califorina, USA
Posts: 2445

The windings loosened up when you let it sit outside because pvc shinks when cooled, but copper doesn't (or at least to a much lesser degree). I wouldn't worrry about them, it is mostly a cosmetic defect.

In the future, it is best to wind the secondary when it is nice and cool (like leave the former out overnight) and paint it after it has warmed up so that the pvc will expand a little and help tighten up all of the windings

HV Enthusiast

Fri Mar 07 2008, 11:49PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Looks fine to me. I don't think it will be a problem. In fact, i can't really see any problems that you describe anyways in your pics.

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