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Thread: Flexmod P3 tech Q.

  1. #1
    Join Date
    Jun 2010
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    NW Montana, USA
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    11

    Default Flexmod P3 tech Q.

    I just got my Flexmod P3s in today (after building dozens of my own LM317 based drivers in the past). What a great driver! Very impressive. I'm using them with both a 200mW 405nM diode, and a 445nM Casio diode. However, I have a question that maybe someone (DrLava?) can answer. I am not using the modulation input (for testing purposes). The specs for the modulation + input (M+) say 0-5V analog signal. Unfortunately, I don't have 5V available. Would it be OK to hook it to V+ (input voltage is 12V regulated), or is it not a good idea to go over 5V ? Also, there is a PCboard pad labeled '5V' on the back side of the board. It doesn't appear to be documented in the instruction manual that accompanied the Flexmods. Is this a 5V output? It measures 0V when the circuit is powered up, so I assume it's an input, perhaps for TTL modulation (on/off) ?

    If it's not OK to use more than 5V on the modulation input, I suppose I'll have to wire up a LM7805L. I have a bunch of these handy little regulators, they're in the small TO-92 transistor package, good for about 100mA of clean 5V power.

    Thanks for any input.
    --
    Greg
    Those blue photons are the prettiest.

  2. #2
    Join Date
    Oct 2006
    Location
    Cleveland, Ohio
    Posts
    2,333

    Default

    Hi Greg, thanks for the on the driver! You can take the modulation input up to 16V directly and it will behave as if 5V supply were there. For 16-24V you'll need a 10K resistor to jump from V+ to Mod+. The input can take many thousands of volts very briefly in a static shock with no problem.
    You can ignore the pad marked 5V on the bottom, originally it had an intended purpose when using low voltage supplies but now it has none.

  3. #3
    Join Date
    Jul 2008
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    north carolina usa
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    216

    Default

    can i get full power out of the driver with only 3v blanking input

  4. #4
    Join Date
    Oct 2006
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    Quote Originally Posted by rgb-gas View Post
    can i get full power out of the driver with only 3v blanking input
    technically, yes, you can set the 'gain' adjustment to your desired current while the input is 3V, however you have to make sure that the input then never goes above 3V or the output current will rise above your set-point up to an additional 66% (5V vs 3V). 5V is the designed input safety cutoff above which higher input voltages will not increase output.

  5. #5
    Join Date
    Jul 2008
    Location
    north carolina usa
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    216

    Default

    thanks i will place order soon jeff

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