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S.C.A.R. 1000 (single coil assult rifle 1000j)

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Marko

Mon Nov 07 2011, 09:37PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hey guys

A ZVS/mazzili driver driving a PC power supply transformer in reverse can achieve continuous output of several hundred watts. I'm not sure why you all still prefer having trouble with all those misdesigned flyback or boost or whatever converters. I hope you can figure out how to build one after all this time!

One trick to use no matter what kind of converter you have is a simple feedback using a comparator with hysteresis. Your converter has to be designed to provide significantly higher voltage than you cap spec so you don't wait for minutes to charge from 380 to 400V if charging to 380 took few seconds.
You can use a voltage doubler (which would also come handy for limiting the current) on the transformer output.

Marko

Saz43

Mon Nov 07 2011, 10:28PM

Registered Member #1525 Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294

ben5017 wrote ...

I am trying to get my scr to work.... I hocked up 2.5 volts to it and still the resistance is 15 M ohms.... what am i doing wrong? link is to the spec sheet

On page 3, I_GT and V_GT are the values you're interested in.

At room temperature (25C), your SCR may require up to 3.0 volts and 150mA to trigger. Try increasing your voltage, and make sure your gate resistor is letting enough current through. But first, have you wired it up like this (from Barry's site)?:

ben5017

Tue Nov 08 2011, 02:21AM

Registered Member #3315 Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 156

saz, I didnt even notice that stuff on the right. I fugured max means maximun not max to trigger.... I feel like that could be worded much better. can you retry that link?

ben5017

Tue Nov 08 2011, 02:28AM

Registered Member #3315 Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 156

I jus tryen a one cell lipo at around 4.25 volts. I tryed it and nothing... i tried hookin the batter the other way and the resistance went up 15 M ohms to 35 M ohms? what would cause resistance to go up? when not on wouldnt the scr resistance jus be overload on the meter?

Saz43

Tue Nov 08 2011, 04:24AM

Registered Member #1525 Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294

ben5017 wrote ...

I jus tryen a one cell lipo at around 4.25 volts. I tryed it and nothing... i tried hookin the batter the other way and the resistance went up 15 M ohms to 35 M ohms? what would cause resistance to go up? when not on wouldnt the scr resistance jus be overload on the meter?

Sorry bout that, link fixed. Sounds like you might have your SCR hooked up wrong, check it out.

ben5017

Tue Nov 08 2011, 06:44AM

Registered Member #3315 Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 156

saz: thx for the help. this is probly a silly question, but my scr has 2 wires out of it and the diagram only has one?. I am tryin to learn as i go along.

Saz43

Tue Nov 08 2011, 04:35PM

Registered Member #1525 Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294

ben5017 wrote ...

saz: thx for the help. this is probly a silly question, but my scr has 2 wires out of it and the diagram only has one?. I am tryin to learn as i go along.

I asked the exact same thing on this forum when designing my first SCR coilgun. The red wire is simply another line to the cathode. The white wire is the gate to which you apply the trigger signal.

ben5017

Sat Nov 12 2011, 09:47AM

Registered Member #3315 Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 156

I Still cannot get my scr to work.. I register like 50 k ohms resistance on my scr ?? shouldnt it be in finite is is broken?

Saz43

Sat Nov 12 2011, 05:25PM

Registered Member #1525 Joined: Mon Jun 09 2008, 12:16AM
Location: America
Posts: 294

Can you give us a drawing, or a photo of how you have it connected?

ben5017

Wed Nov 16 2011, 09:46PM

Registered Member #3315 Joined: Thu Oct 14 2010, 04:23PM
Location:
Posts: 156

saz, one of my friends tryed hookin it up for me he is an EE and couldnt figure it out i took it apart after it wouldnt work... I tried every way to hook it up and fear i broke it somehow. Why would my multimeter read a resistance when the scr is closed? shouldnt it be infinite? If someone would be so kind as to make me a nice simple drawing.. I have limited EE experience so sometime spec drawings just confuse me even more. this is the last obsticle befor the SCAR1000 is ready to fire so any help is greatly needed

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