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Thread: Experimentonomen´s first argon.

  1. #1
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    Laser Warning Experimentonomen´s first argon.

    Yesterday my first argon laser arrived, i bought it for just 160-170USD shipped from australia.

    Heres some pics, the box:


    After removing a rainforest worth of newspaper, this is revealed:


    Out of the box and sitting on my laptop:


    Some numbers:


    BeO warning sign:


    Filament connections:


    Peering down the OC:


    The HR:


    And this is a video of testing out number of turns for the filament winding, a nice orange glow can be observed through the OC, tho the camera seem to think its white:

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    The reason the camera picks up the orange as white, is because most of the light emitted is in the infrared range. Incase you were wondering

    Looks like a nice laser

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    Heres the schematic of the current regulator i plan to use, if it will work in reality remains to be seen.



    I also plan to add a NE555 based 1Hz flasher to the overcurrent LED to make sure it gets the users attention, i may even add a latching circuit that kills the power to the tube in an overcurrent event.

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    You need to add ignitor protection to the mosfets.

    steve
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    =mixedgas;131976]You need to add ignitor protection to the mosfets.

    Also add a .5 to 1 ohm resistor on the anode side of the tube to get the I/V curve in a more positive region.

    I assume you know to center tap the cathode transformer.

    steve[/QUOTE]
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    Mixedgas, i have all that covered.

    The tube have now found a home it likes and is moving in:





    However the box will be cleaned up and repainted black, also i´m going to make some flaps to direct the air flow through the fins before it enters the fan and drill holes in the bottom and sides for air to enter, tho i have my doubts about that moldy computer fan, but its all i have for now, except a 48V fan currently living in a large 3phase smps.

    I´ve bought a Laser Drive Ar Ion ignitor board so the passbank protector may already be in place there, otherwise i´ll just put a 10µF and 100nF cap in parallel between the filament transformer centertap and the DC bus from the psu, that should catch the ignitor pulse and keep it away from the passbank.
    Last edited by Experimentonomen; 01-14-2010 at 06:41.

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    Thats not the normal way of protection. Usually a 60-90V 5 watt zener across the fets with 100 ohms in series, and a 1N1190A (1100V, 40A) blocking diode on the anode feed. Most lasers have the blocking diode in the head and it doesn't show on schematics. JDSU/Spectra put it in the PSU. Lexel uses a 1 microfarad 600V mica cap designed for RF bypass from the anode to the negative rail. The ignitor itself will not catch the pulses, and needs the cap as a RF return.

    For most tubes, your fets in parallel, ie your ESR , needs to be equal to be a 5 to 7 ohm resistor.

    Your basicly making a lexel 75 supply with fets. In fact if you used a IR540 linear FET in the To3 can, it can drop in directly in a lexel PSU, provided you replace all the NPNs with fets. Hope you have a big heatsink!

    Steve
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    Quick progress!!

    I like your driver schematic too - Steve, would this design be able to power an ALC60 head up to 10A? I actually have a cathode transformer for one here ... but I lack all the other bits and bobs that are needed to power the tube.

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    Im making a psu similar to sam´s sg-il1 and he uses the 10-0.1µF caps between the cathode and the DC bus, no zener, im gonna use IRFP450´s or some igbts on a forced air cooled heatsink.

    Btw that 1N1190AR diode is a 600V diode from what i can see in the datasheet.

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    Quote Originally Posted by Experimentonomen View Post
    Im making a psu similar to sam´s sg-il1 and he uses the 10-0.1µF caps between the cathode and the DC bus, no zener, im gonna use IRFP450´s or some igbts on a forced air cooled heatsink.

    Btw that 1N1190AR diode is a 600V diode from what i can see in the datasheet.

    I'm the guy who helped SAM build the SG-il1. I'm the principle contributer to the ion laser chapter.Use the zener. trust me... IGBTs dont go linear very well. Keep the fets all mounted close together so they track. By track, I mean if one starts to heat up, it will back off its conductance and the two next to it will pick up the slack. If you can keep them thermally close together, it prevents hotspots and avoids popping fets. I'd place a fuse in the tail of each fet at about twice or triple what the fet would be conducting. The Fets fail shorted. 220-330 ohm resistors in each gate lead would help reduce the peak load on the opamp and reduce clipping. At any given time I'm responsible for 12 of these linears from air cooled to 35 amps 220, so I'm suggesting adding parts that should be there. lexel uses 1 follower opamp for every 4 FET gates on the more modern PSUs. First test after building is to make sure the FETS are biased FULL on before the ignite spike hits them.

    Steve
    Last edited by mixedgas; 01-14-2010 at 08:13.
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