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Thread: Learn me something electronical...(Flexmod)

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    The best way to be certain is to stick your meter (in DC volts mode with max voltage setting above 24v) across the V- and V+ terminals and switch on. If you get a reading of 12v (pos or neg will depend on which way round you put the leads), then V- is 0v with respect to V+. If you get 24v then V- is -12v and FG is 0v with respect to V- and V+.

    If you get 12v in the above test, then G on the P3 goes to V- on the PSU. Do the same test on the 5V PSU and if you get 5v on the meter then link the V- of the 5v PSU to the V- on the 12v PSU.

    When you come to build your projector, I believe it is best practice to connect all the 0v terminals to one central point to prevent ground loops (I even did the base plates and PSU frame grounds on mine just to be sure). My P3's now only have 3 wires to each unit with the G points connected to a single common wire that goes to the central point. Works lovely!
    Cheers

    Colin.

    Anyone wanting to be a politician, should automatically be excluded from being one!

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    I've not had a chance to work on it further as we had several events this past weekend and I took my staff to an amusement park today but, I'm looking forward to getting back to this either tomorrow of Wednesday. Thanks guys!

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    Woo Hoo! Getting somewhere. I was able to set the O Bias at 150mA but, the meter I have with me probably won't go high enough to measure the current to set the gain. (My other meters are an hour round trip away.) However.... it's only a 2 amp 12V supply and according to buffo's sale thread:

    http://www.photonlexicon.com/forums/...ll-the-goodies!

    He ran them at 1.8 amps so... can I safely, just for testing, go ahead and hook them up and turn down the gain pot a bit without frying anything?

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    Next silly question... I went ahead and hooked the diodes up in place of the multimeter, without ungrounding the V+ M lead and at 150mA, I'm getting a lot more than just a faint beam... I'm getting about 101mW measured using a Laserbee. Uh... ? Shouldn't it be a barely perceivable beam?

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    Forget the last question. The middle pot turned down a little allowed me to get the O Bias down to where I have just a barely perceivable dot on the wall and it doesn't even make the Laserbee register anything. Now for the REAL power... do I live dangerous since it's only a 2 amp supply or go buy a (yet another) meter?

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    make sure you heat sink the big fet transistor on the flexmod before cranking the current up!

    Quote Originally Posted by Bradfo69 View Post
    Forget the last question. The middle pot turned down a little allowed me to get the O Bias down to where I have just a barely perceivable dot on the wall and it doesn't even make the Laserbee register anything. Now for the REAL power... do I live dangerous since it's only a 2 amp supply or go buy a (yet another) meter?
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    Done. And I've turned down the gain pot about 15 turns to start.

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    Success! No guts but... success. I slowly cranked it up to a little over a watt which overflows the Laserbee so I need to dig out my Scientec meter. Now is when I had a meter I felt comfortable trusting.

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    Quote Originally Posted by Bradfo69 View Post
    Woo Hoo! Getting somewhere. I was able to set the O Bias at 150mA but, the meter I have with me probably won't go high enough to measure the current to set the gain. (My other meters are an hour round trip away.)
    Does your meter have a third input point (lead connector, sometimes yellow). If so this is likely to be a high current only connection. You plug the Red lead in to it, set the meter to Amps on the range setting that seems to have two values (often written like a fraction or a division eg. 20m/10A). Be aware this connection is usually fused (most times found in the battery compartment) so it is a good idea to find the fuse and test it (with the meter on the ohm range and the lead back in the red connector) before you start.

    Good luck
    Cheers

    Colin.

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    Hi Colin,

    Not this meter. My good meters do but they're in my storage unit about 1/2 hour away. This is just a little basic $15 Radio Shack hobby meter. I normally have one of the good meters in the trunk of my car (I've got 2 or 3) but, I cleaned it out recently and left them in the storage unit.

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