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Thread: To TELEK. Sproggy2.7 ATX

  1. #1
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    To TELEK. Sproggy2.7 ATX

    I just finished building the sproggy 2.7 ATX version found in your site and think that there is an error in your component layout :
    The LM340 Strap should be linked to the +12V coming from the remote (going to the relay) and not to the +12V of the circuit as it is in your layout. Is it right.(I have modified the circuit and now the relay clicks, it didn't before the modification)
    Another question , have I to put a heatsink for the LM340.
    PS : I Haven't yet cheked the various output voltages and delay, will let you know how it goes as soon as done.
    Thanks.

  2. #2
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    No, well, it depends how you want the PSU to work.

    My reasoning was that if you were going to use anything other than your car ACC line for the remote (for example your radio remote out) then you cannot draw the +5VSB off of the remote line (because it can take up to 1.2A on spec and 2.4A total). If you use a shutdown controller as well then you can still leave the remotes attached to your radio (or anything else that provides a low amperage remote signal, or low amperage switch with small wires).

    If you are going to use a shutdown controller, then there is no need to use the remote lead at all, just tie both of them together.

    If you are going to use the ACC line for remote then yeah, you can just tie the LM340 to remote instead of the unswitched +12V in.

    However I think that it would be better to add in a single 2N2222A (current limit of 600mA which is > 500mA ATX spec) and then attach the remote line to that, and leave the LM340 attached to +12 unswitched. But it's really up to you I guess.

    How are you planning on powering your PSU? Directly to +12v unswitched and ACC or through a shutdown controller?

    Part of the reason that I left the connection as a jumper instead of a trace was so that you could decide yourself where you wanted it to go. If you want to switch it to the ACC line then it's relatively easy to do so without changing the PCB itself.

    Do you have a digital camera? I'm really anxious to see how this works out and how it looks. I'm a little worried about traces being too close together and too thin so I have been modifying the layout a bit to allow for a larger seperation between traces and thicker traces. Make sure to tell us how it goes?

    What modification did you do to make the relay click?

    It you can, put a heatsink on the LM340 as it would be advisable (it'll burn off up to 3.5W if you use a full 500mA ATX spec or 7W if you go crazy and use the full 1.0A available. I don't think it's absolutely necessessary as you should never really use more than ~200mA or so on that rail (but the 100mA that it was set to before was nowhere near enough) which should be enough to operate without a heatsink. Check the PDF file for that component to see what they say. Better safe than sorry, I put both those 2 components right next to each other so that you could easily add a heatsink to the both of them.
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

  3. #3
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    I am planning to power my PSU directly from the ACC througt the relay by using a remote button and the remote line is also supplyed from the ACC).

    The modification I talked about is wiring the LM340 to the remote line.(When wired to the unswitched 12V like in your layout it didn't work).

    I am confused by what you said about putting a heatsink for the 2N3904 since the mine is a small one (looks like a transistor) without heatsink holder.

    Now i have checked the voltages, everything is OK except the 5V standby wich is at 12V? What is happening?
    As far for the powergood, what is its normal voltage.
    Thanks for helping

  4. #4
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    Now it's OK for the powergood (3.3V). The only problem remains with the 5V standby wich is in fact at arround 10V?.
    The LM340 I'm using is an LM340 T15. May this be the problem. Have I to use a normal 78L05 regulator.

  5. #5
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    Again me, My problem comes from the LM340 T15 wich have to be LM340 T5. I'll replace it tomorrow.
    What about the heatsink for the 2N3904?

  6. #6
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    I really don't think that the 2N3904 needs a heatsink, but you can if you want.

    I forgot, the main reason why I put it off of the +12V is because if you want to be able to leave your computer in S3 STR (suspend to ram) mode then you cannot put this on the remote, it must be put off of the +12V unswitched.

    LOL you're right, I should have attached the LM340 to the unswitched +12V, but I put it on the other side of the relay... oops!
    IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.

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