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Will1234

Tue Jun 19 2007, 08:12PM

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

Hi everyone,

I ran across a few posts concerning the SSY laser and PFN. I have an SSY, PFN, and Trigger board but am unclear about the PFN connections. The SSY to PFN connections are pretty straight forward but am unsure about where to apply the energy capacitor charge voltage.

The other thing concerns charging the capacitor to the desired voltage and firing the lamp. When the lamp is in the process of firing the charging current the energy capacitor needs to be either diverted or paused so it doesn't go into a dead short. How have any of you made the PFN connections and dealt with the charge current while firing?

Any information anyone can provide will be Greatly appreciated.

Will

...

Tue Jun 19 2007, 09:20PM

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

Let me start out by saying that you made a great choice by getting a ssy-1 laser, you won't regret it--just as long as you have a good pair of od5+ yag googles.

As to the PFN, I prefer not to use the PFN as a whole circuit, but rather strip out the revelent pieces (main cap, inductor, trigger cap, trigger transformer, connectors for the flashlamp) since most of the parts are unnecessary.

The main cap is a pain to get out, you pretty much have to take a saw/grinder and cut a few slots in the aluminum frame (woodworking tools work great) and break it apart), but it works just fine to leave it in the frame. Just unsolder the extra parts and throw them in the junk pile. Then wire the cap->inductor->flashlamp, and then use a high value resistor (1meg is fine) from the + of the main cap to the trigger cap (the big yellow one on the trigger board), and then wire the trigger transformer (in series with a momentary switch) across the trigger cap. Give the main cap 700v and hit the button in series with the trigger transformer.

As to shorting out your charging supply, the supply need to be able to withstand a dead short anyway since the cap will show up as a dead short when you start charging. The standard solution is to just use a current limited supply, or add a resistor in series with it.

As to the high currents, so long as you use >16awg wire and solder all of the joints you will be fine.

Not sure if you found my thread yet, but I posted my results here

Will1234

Tue Jun 19 2007, 11:39PM

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

Thanks so much for your reply. Once I get a few minutes I'll pull everything together and digest everything. I hadn't seen your post yet (not sure how I missed it) but will study it as well. Thanks for now, I'll be back in a couple of days.....

Will

Will1234

Wed Jun 20 2007, 04:23PM

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

I'm so pumped about getting this up and running that I took a few days off work to dedicate to it. I'm ordering a second PFN from Meredith that I will autopsy and remount the parts similarly to how you did. For now, I really want to get the stock PFN up so I can drive the pump at a fast pulse rate.

Specific to my confusion surrounding the PFN connections:

It looks like the vacuum relay is in a normally closed state and has to be opened to actually charge the cap. Is this correct? Is it opened by applying current (about 24v) to the relay?

One connection is labeled +900v (P1-9) on the schematic I have from Sams FAQ and assume that this is where the capacitor charger + is applied. Is this correct?

Is the connection labeled Ground (P1-13) referring to the ground (-900v) of the +900v charging current?

Another is labeled Logic Trigger (P1-3) I have read will need a 'logic level signal (low)' to turn on Q1? Specifically, what is a low logic level signal? Is it +5 volts???

My biggest source of confusion is coming from my lack of understanding. Do each of the connections requiring power as input have independant gound connections or do they all share the same gound connection? Because of the voltages in use I have been unwilling to just connect everything and give it a try. Again, all of this (for now) is using all stock components, SSY1 head, PFN1, and TRG1.

And as before, any information or guidance you can provide will be Greatly appreciated.

Here are links to the diagrams I'm using.....

Will

...

Wed Jun 20 2007, 08:51PM

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

The vacuum relay is normally closed, so you either have to give it voltage(24v would probably work) or cut one of the wires going to the hv terminals on it.
The +900v terminal on the schematic is where you connect your charger (which, remember, has to be able to take a dead short)
The ground connection is the common negative terminal for the whole system (save for the vacuum relay), and is where you connect the - terminal of the charging supply. You should connect both of (pins 13 and 20) together.
To fire it you need to give it some voltage on the trigger pin (not sure how much, I would start with 5v, then 12v and then 24v) to charge the cap C3, and then when you pull it low (0v) it will discharge the transistor(Q1) into the SCR (Q2), which will dump cap C2 into the trigger transformer and fire the laser.

Will1234

Wed Jun 20 2007, 11:09PM

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

Fantastic, I'm starting to shake I'm getting so excited.....

Just saw your signature. LOL. My favorite signature of all time (so far):

"There at 10 types of people in the world, those who understand Binary and those who don't"

Will1234

Thu Jun 21 2007, 04:00PM

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

I was able to unmount the vacuum relay and operate it with a 9v battery. I'm planning on charging it via a 9v battery and a second (fail safe) momentary switch. More to follow........

Will1234

Mon Jun 25 2007, 05:37PM

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

I'm back..... I have a 1300 VDC 30mA capacitor charger in hand. Because the SSY1 capacitor is 950v I don't think I want to try a direct connection. Does anyone know how I can pull the charger down to the 700v - 900v range?

W

...

Tue Jun 26 2007, 05:50AM

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

It it was designed for charging caps (ie, it puts out a constant 30ma regardless of if it is putting out 1v or 1kv) then you don't need to do anything. Just put a voltmeter on the cap and make sure you don't overcharge it (the cap will probably take 1200v, however you run the risk of frying the internal q-switch with shots with >700v)

If not, you need to add a resistor in series with it, if it is going to complain if you try to draw >30ma from if you would need a .5meg resistor (you are dropping 1300v at 30ma, so use v=ir), which will need to be able to dissipate the full 40w that supply can put out (at least for short periods of time).

Will1234

Fri Jun 29 2007, 02:43PM

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

Real life keeps interrupting my fun! I opted to fall back and regroup a little. Back to dismantling the PFN and TRG. Everything has been pulled apart and I'm in the proces of re-assembling things as you described but am not sure about the resister you mention.

"Then wire the cap->inductor->flashlamp, and then use a high value resistor (1meg is fine)"

Does the Wattage of the resister matter?

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