Newb needs help with a relay

Discussion in 'The Projects Forum' started by techtrino, Jul 23, 2010.

  1. techtrino

    Thread Starter New Member

    Jul 23, 2010
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    Hey Guys

    All new in here so dont be to hard on me.

    I am building a DIY Vidock, thats taking a ordinary pci-e graphics-card and hooking it up to your laptop.
    Now I am using a standard ATX PSU to power my GPU, and I am putting it all in a nice lille Lian li case.

    The problem is:
    The case has a momentary switch, which is nice and I want to keep it, but I need to be able to turn on the PSU without a motherboard.
    So... I want to use a small 5V relay as the PSU has a constant on 5V line (purple lead). Simple I quess. But I dont know enough electronics to make one.
    Would one of these do it?

    http://cgi.ebay.com/Relay-Board-1-R...tem&pt=LH_DefaultDomain_0&hash=item3a5c4f6dd4

    Simple for you guys I know:rolleyes:
     
  2. windoze killa

    AAC Fanatic!

    Feb 23, 2006
    605
    24
    You don't really need a relay. If you short pin 14 (/PS_ON) to a ground pin that will trick the power supply into thinking it is plugged into the motherboard. Now when you press the switch it will work fine.
     
  3. techtrino

    Thread Starter New Member

    Jul 23, 2010
    8
    0
    Which switch? I know about the "paperclip" trick, but then the psu is on all the time, I would like to turn on the psu with the switch on the case
     
  4. tom66

    Senior Member

    May 9, 2009
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    You need a latching switch, one you can push and it stays down. Otherwise, if you want to use a normal push button switch to turn it on and off, you will need some kind of set/reset logic. The logic could then go to an open collector NPN, and the circuit can be powered off the standby 5V line.

    You are trying to connect a full power PCI-E card to a laptop slot? Good luck, you'll need it, you're dealing with very fast frequencies and you will likely have way too much capacitance for it to work properly. Each lane in PCI-E is clocked up to 1 GHz and you may have as many as 16 lanes where you need to eliminate cross-channel noise and interference, you must also have minimal capacitance to get a good signal and a distance of no more than a few inches. Otherwise, it won't work properly, if at all. Also, I'm not sure, but aren't laptops compatible only with a few cards?
     
  5. techtrino

    Thread Starter New Member

    Jul 23, 2010
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    Yes, will the one I link to do the job?

    Nja, there is a lot working done on the DIY Vidock, nothing new, and it works, I dont need luck ;)
    I will be looking at 50% performance of e.g. a gtx460, which is very fast on my x201 :D
     
  6. tom66

    Senior Member

    May 9, 2009
    2,613
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    That's not a latching switch or relay circuit.

    As said, you will only need a switch, which when pressed down, stays down.

    If this is unavailable, let us know, I'll find a set/reset circuit.

    I am curious how the DIY Vidock works.
     
  7. techtrino

    Thread Starter New Member

    Jul 23, 2010
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    0
    Well I would like to keep the momentary switch on the case, so I thought all I needed was a relay to keep the power on or off :S

    So what do I need, preferably something already build, as if I need to get parts etc, shipping and customs fees etc will be quite expensive (I live in Denmark and we have a customs fee of 30usd + 35% tax on everything from outside of the EU)

    Here is a link to where we discuss the DIY Vidock, quite easy actually, almost plug and play
    http://forum.notebookreview.com/gaming-software-graphics-cards/418851-diy-vidock-experiences.html
     
  8. tom66

    Senior Member

    May 9, 2009
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  9. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Not quite true. You can use a flipflop to toggle the output on each trigger input. I am working on a circuit at the moment and will post it when I finish it.
     
  10. windoze killa

    AAC Fanatic!

    Feb 23, 2006
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    Here is a bit of a circuit. Bit of a rush job but I think it might work.
     
  11. techtrino

    Thread Starter New Member

    Jul 23, 2010
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    0
    Thank you, but did I mention that I am a bit of newb, I dont know how to read a diagram like that, other that there are different resistors etc :)
    Are there no commercial available solutions? It just seems odd that you can buy all these momentary switches but no "flip flops"
     
  12. tom66

    Senior Member

    May 9, 2009
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    You can buy flip flop chips and the circuit windoze_killa posted uses one.

    There are unfortunately few other ways without resorting to a microcontroller.
     
  13. techtrino

    Thread Starter New Member

    Jul 23, 2010
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    0
    Yes, but I dont know how to build it even with a diagram and the flip flop :(
     
  14. BMorse

    Senior Member

    Sep 26, 2009
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    It is not that hard to replace a switch in the case, if you are out shopping for a relay, why not shop for a replacement switch that will fit in the case, then your problem is solved! Since you can not really read schematics and such (not trying to put you down, just going by what was said) I believe the easiest method to accomplish this is to find a latching switch to replace the one on the case, since no matter what type of flip flop circuit or latching relay circuit people come up with, I believe it will still be way over your head to get it built..... stick with looking for a replacement switch, then maybe someday when you are a little more experienced you can build a different circuit..... remember K.I.S.S. .......

    B. Morse
     
  15. Melchior

    New Member

    Feb 2, 2008
    9
    1
    Its possible that my ATX power slave may be useful here;

    If there is a 5 volt supply from the laptop then you can use my circuit to control the 'slave' PSU. (USB power possibly ?)

    http://forum.allaboutcircuits.com/showthread.php?t=41025

    Otherwise its building the usual Flipflop (toggle) circuit.
     
  16. BMorse

    Senior Member

    Sep 26, 2009
    2,675
    234

    It may help if the OP can replace the switch with a latching one, if he keeps the momentary switch in the case this circuit will still not work, since there still wont be a way to keep the input on to the optocoupler without a latching switch....

    B. Morse
     
  17. soda

    Active Member

    Dec 7, 2008
    174
    13
    To latch a relay is a easy task. Connect the relay to the power supply as you did it in the first place. Connect now the wafer of the relay to the +v side of the power supply and add a link between the NO (normally open) contact and the +v side of your relay. This will latch the relay until you power off the computer. See it's easy and you don't need any transistor circuits for the job.
     
    Last edited: Jul 26, 2010
  18. soda

    Active Member

    Dec 7, 2008
    174
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    Have a look at this diagram then you know how to connect the relay
     
  19. BMorse

    Senior Member

    Sep 26, 2009
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    Ok, this will turn it on, but how will he turn it off without unplugging the main AC power cord??

    B. Morse
     
  20. soda

    Active Member

    Dec 7, 2008
    174
    13
    BMorse, that is so, so all I can suggest is to add a PTB switch on the supply line and then he just have to remember to reset the relay each and every time he power down the computer.
    Fix it in a small plastic box with a red led indicator .Connect the led to the other side of the relay so when you press the switch, the led turn off and reset the relay all in one action.
     
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