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Thread: I made my first arch - now i have a 27plug problem

  1. #21
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    Default Re: I made my first arch - now i have a 27plug problem

    Quote Originally Posted by smartalec View Post
    bugger david saying 1.5mm , i only have 2mm in stock.. might have to go for a drive to get some more.

    how much current can you pull from them type of d-sub plugs? at 24v dc ?
    2mm heatshrink may be fine too. Try a small piece and see if it shrinks down nicely.

    D series pins are usually rated for 1 Amp.
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  2. #22
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    Default Re: I made my first arch - now i have a 27plug problem

    sweet you saved me the drive david, its too hot to go out anyway 31c here now thats 90f over there (that would melt the snow for them) mmm cold snow..aarrrr

    ive posted pic's on how i made the arch, is this how people are doing there archs or did i do something different.

    1amp..mmm didnt know that, but would u get crosstalk if all pins were loaded with 24v with 1amp pulling on them?

    i know the 8pin din plugs did well doing 2amps at 36v a couple of yrs ago.
    (my rewired icecle lights)
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  3. #23
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    Default Re: I made my first arch - now i have a 27plug problem

    The current rating is per pin. If you used one pin as a common, you'd be limited to 1 Amp total. Paralleling spare pins for the common will get you more total current capability.
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  4. #24
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    Default Re: I made my first arch - now i have a 27plug problem

    Quote Originally Posted by David_AVD View Post
    The current rating is per pin. If you used one pin as a common, you'd be limited to 1 Amp total. Paralleling spare pins for the common will get you more total current capability.
    so im basicly going for 37 pin plug then , so i have 1amp per channel.

    also i only did 20 green leds per 25cm segment, is that too little?
    the red has 30 legs per segment, way the big W leds are wired
    Over 50000ch last yr

  5. #25
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    Default Re: I made my first arch - now i have a 27plug problem

    im going to end up using a 37pin d-sub plug,
    ive also been measuring on the led lights i got.
    an it looks like they dont even use 100ma.
    So ive made this circuit up, i think its correct, please tell me if its wrong
    the chip is rated for 500ma up to 50v DC
    designed to connect off the renard64.

    pcb board.


    sch pic.


    thanks
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  6. #26
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    Default Re: I made my first arch - now i have a 27plug problem

    A few things:
    - The 500mA rating is further limited by total package dissipation - check the data sheets.
    - You need to beef up your ground traces (and the light supply traces - see below)
    - You have the flyback diodes tied to "Vcc" but there's no Vcc on the board. Since you are just driving bulbs, you can leave them unconnected
    - The ULN2803 are sinking drivers. They pull their output pins to ground. The other side of the lights need to be connected to a supply voltage, not to ground. Tie the middle pins on the DC37 to V+ and add a connector to source this voltage to the board. Watch the current rating on your input connector as 16 channels * 100mA = 1.6A

    /mike

  7. #27
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    Default Re: I made my first arch - now i have a 27plug problem

    thanks for the help, i'll get around to fixing it in a couple of hrs.
    anything else i might of done wrong?
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  8. #28
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    Default Re: I made my first arch - now i have a 27plug problem

    OK
    now i seem to be having problems getting the gnd an vss rails fatter,
    but i think this ver should be correct??
    it's been awhile since ive done electronics.
    sch

    pcb


    thanks for the help.
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  9. #29
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    Default Re: I made my first arch - now i have a 27plug problem

    The diode pin on each ULN2803 should go to the positive rail. (Vss in your diagram) BTW, Vss usually refers to a ground or negative power rail. It would be better to use Vcc or V+ IMO.

    This may have been mentioned already, but the ULN2803 are active high inputs I think but the controllers for most SSRs use active low don't they? If that's the case, your ULN2803s will just sit there. If you added pull-up resistors on each input to the 5V line and inverted the controller logic it should work though.
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  10. #30
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    Default Re: I made my first arch - now i have a 27plug problem

    Quote Originally Posted by David_AVD View Post
    The diode pin on each ULN2803 should go to the positive rail. (Vss in your diagram) BTW, Vss usually refers to a ground or negative power rail. It would be better to use Vcc or V+ IMO.

    This may have been mentioned already, but the ULN2803 are active high inputs I think but the controllers for most SSRs use active low don't they? If that's the case, your ULN2803s will just sit there. If you added pull-up resistors on each input to the 5V line and inverted the controller logic it should work though.
    my mistake, im using the Vss an the +power rail

    so you meen i need to install iverters just before the ULN?
    Last edited by smartalec; 02-02-2010 at 07:47 AM.
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