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Will1234

Tue Jul 17 2007, 02:40AM

Registered Member #846 Joined: Tue Jun 19 2007, 08:04PM
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Posts: 40

The Q-Switch is out and I'm certain that it is out of alignment so I will try to address this in a day or so. If the Q-Switch is gone the rod loses its ability to get a peak pulse doesn't it as the Q-Switch kept everything bottled up until the time was right. Following this logic, am I likely to notice a drop in output when running from the same PFN capacitor as before? Is there a rule of thumb or something that will let me know where I now sit on the power curve as opposed to where the Q-Switch had me?

Now what everyone kept telling me was inevitable, more power. You mentioned that the flash tube should be good up to about 200J and the cap is rated at 900V. Never having seen a flash tube or capacitor explode first hand one first hand, I'm not sure what precautions to take. Is the fact that the tube is in the chamber and the old PFN cap is still in the partial metal cylinder of any value if either explode?

...

Tue Jul 17 2007, 03:24AM

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

The flash tube will probably not explode too destructively, you might crack the glass or blow out one of the electrodes. The tube is shot, but the laser is fine. As to the cap, if it dies it is trash... But really it is way more cost effective to use electrolytics for high power shots...

The power should actually go up by removing the q-switch, but the ball of flame produced will be notable smaller, due to the lower peak power. At 20j you probably won't see much of an effect on the target unless you focus the beam down to a decently small spot.

Will1234

Tue Jul 17 2007, 11:21PM

Registered Member #846 Joined: Tue Jun 19 2007, 08:04PM
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I was concerned that if the cap were in the metal housing and it expoded does it become a shaped charge at that point or is it a fairly mundane event??

...

Wed Jul 18 2007, 12:46AM

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

There isn't more then 30J of energy stored in the cap, so even if it were to explode all of the sudden it wouldn't be to deadly... IIRC, I overvolted one of the caps and then it started to make a crackling sound, but didn't explode.

Will1234

Wed Jul 18 2007, 08:11PM

Registered Member #846 Joined: Tue Jun 19 2007, 08:04PM
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Posts: 40

I'm getting ready to pull everything apart and realign it. One thing I noticed with the rod when i had it out the first time is that it appeared to have a light 'frosting' dust layer on it. Not completely obscuring the color of the rod but noticeable. Shouldn't the length of the rod be as clear as the end faces or at least not looking as if it were frosted?

...

Thu Jul 19 2007, 01:24AM

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

The sides of the rod are ground ('frosted') only the ends have been polished/coated.

Will1234

Fri Jul 20 2007, 01:01AM

Registered Member #846 Joined: Tue Jun 19 2007, 08:04PM
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Posts: 40

All is back together and working. I have a second PFN in hand, as long as the caps are similar is there any inherent danger in connecting the two in series and discharge them both in the same setup? If in series, does the max charge for both caps acting as one double to 1800v? If so, I can run my 1300v power supply unencumbered and drive the lamp harder.......

...

Fri Jul 20 2007, 02:58AM

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

You would definantly want to put both caps in parallel.

Will1234

Tue Jul 31 2007, 03:28AM

Registered Member #846 Joined: Tue Jun 19 2007, 08:04PM
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Posts: 40

Currently everything is connected as you described and working with 1 cap. I am noticing that triggering the lamp isn't consistent with what appears to be any cap voltage up to 1100v. Could it be that the trigger cap is losing its charge somehow losing its charge? The main cap charging power is on at these times so so I don't see how this could be the case. Could I put a 100v diode in the + side of the cap charging lead to see if it would make a difference? Also wondered about using the SCR to dump the trig cap...?

...

Tue Jul 31 2007, 05:32AM

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

I very highly doubt that cap is loosing charge, but to rule that out just (while the main cap is discharged) connect a voltmeter to the trigger cap, charge up the main cap, note that voltage is speked 250v.

More likley is that the tube is started to show signs of abuse...

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