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Navrit Bal

Thu Nov 18 2010, 11:54PM

Registered Member #3323 Joined: Sun Oct 17 2010, 03:19PM
Location: West Midlands, UK
Posts: 116

Would this sort of diode with this kind of specification work for me

? I know some values are overkill here

GhostNull

Fri Nov 19 2010, 09:47PM

Registered Member #2648 Joined: Sun Jan 24 2010, 12:45PM
Location: Australia
Posts: 291

That's over kill alright. I don't think you'll get 4500amps kick back. A faster diode would be a better use of your money. I doubt you'll get over 300A kick back (check using the RLC sim) so a diode with a surge rating over 300A would likely be overkill.

Navrit Bal

Fri Nov 19 2010, 10:01PM

Registered Member #3323 Joined: Sun Oct 17 2010, 03:19PM
Location: West Midlands, UK
Posts: 116

I was mainly checking to see if these stud types would actually work, what about this then

Since I am a student, I can get a 5% discount from farnell, and free shipping

Double win!

Also, on an entirely random note, does anyone know where the phrase 'winner, winner chicken dinner' comes from ?

Pinky's Brain

Sat Nov 20 2010, 12:05AM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

That's way expensive ... if you really need near a 1000 ampere try this one.

Ghostnull is probably right though ... and for a couple 100 Ampere of surge current a P600x would suffice.

Navrit Bal

Sat Nov 20 2010, 10:21AM

Registered Member #3323 Joined: Sun Oct 17 2010, 03:19PM
Location: West Midlands, UK
Posts: 116

I think 5 of these

for Â£2 might be better.

Also what does 'Forward Voltage VF Max' mean and why are they usually around 1V ?

Pinky's Brain

Sat Nov 20 2010, 12:44PM

Registered Member #2901 Joined: Thu Jun 03 2010, 01:25PM
Location:
Posts: 837

Farnell has a lot of entries with plain wrong descriptions ... the Ifsm of that diode is only 200 Ampere in the datasheet. The P600J is cheaper and larger.

For 3A diodes the 1n5408 clones tend to be cheapest.

Vf is the forward voltage drop at common currents, for surge currents look at the IV graph in the datasheet though.

PS. if you do go with 3A diodes (Ifsm=200) you will need balancing resistors again, around 0.01 Ohm should suffice.

Navrit Bal

Sat Nov 20 2010, 01:27PM

Registered Member #3323 Joined: Sun Oct 17 2010, 03:19PM
Location: West Midlands, UK
Posts: 116

The higher values for this particular model

seem worth it for the extra 30p and this one is actually in stock

Just to be clear, I intend on using this in anti-parallel with the coil.

Also, can anyone give any advice on coil winding without a machine? Is there any particular technique to follow?

Artikbot

Sun Nov 21 2010, 02:29PM

Registered Member #3247 Joined: Mon Sept 27 2010, 09:42AM
Location: Spain
Posts: 137

I can say that the best winding way I've experienced (I use fairly thin wires though) is attaching wire to the barrel (through a hole and taped down), starting to wind pressing wire down to the barrel with my thumb, and when I reach the end of the layer, simply start turning backwards via gluing the first turn of the second layer to the last one of the first layer.

And keep doing that until the coil is ready.

With thin wires it works awesomesaucely to wind layer>cover with tape>glue the first turn>wire the layer and all over again.

Navrit Bal

Sun Nov 21 2010, 05:15PM

Registered Member #3323 Joined: Sun Oct 17 2010, 03:19PM
Location: West Midlands, UK
Posts: 116

Thanks, I guess the wire should be wound in the same direction? I think I'll probably have to do it you way, Artikbot.

Would it be better to use 4 450V computer grade capacitors with a total capacitance of 5.4mF instead of 105 photoflash capacitors at 330V (Only about 40 are actually marked with rated values) total capacitance is 16.8mF.

The only potential problem is my supervisor not wanting me to use higher voltages. My only arguments that I can think of is that it should work better because of lower resistance because of the massive amounts of solder that I have to use to essentially make wires to bridge the photoflash capacitors. Whereas if I only use 4 capacitors, I could use actual wire or aluminium bus bars instead of solder. Therefore I wouldn't have to rely on my dodgy soldering as well.

I measured my coil as 0.5 Ohms, but on Barry's inductor sim, it comes up as 40 milliOhms and inductance as 57uH, is my multimeter wrong ?

Artikbot

Sun Nov 21 2010, 07:38PM

Registered Member #3247 Joined: Mon Sept 27 2010, 09:42AM
Location: Spain
Posts: 137

Are you sure you plotted in wire diameter correcty?

Oh yes, you keep winding clockwise or counterclockwise all the time, never change that! You just move from left to right, but never change winding way!

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