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Timed Start Up Controller?

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  • Timed Start Up Controller?

    Hey guys, I'm having a pain in the *** time trying to solve a simple problem. I have an ADATA AE800 portable wireless hard drive. I plan on dismantling it and hardwiring it into my car so it turns on when the car is on. However, the power button needs to be held down for 2-3 seconds for it to turn on and start Wi-Fi. So I need a start up controller that detects 12V and sends a trigger that holds for 2-3 seconds instead of just on/off. Is there an easy solution to this? I can set the hard drive to turn off automatically after 5-30min of idle time so turning off isn't an issue, though it would be nice. It seems all of the start up controllers and PSUs just send a quick pulse to turn things on.

    Thanks ahead of time!
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  • #2
    You could use a relay with a 555 timer circuit or capacitor circuit to latch your relay for the time required.

    On a normal relay you have a coil side and the Switched side. So you have 4 different connections. You could have polarized connections for the coil but not necessarily. Polarized meaning one needs to be + and the other -.

    In a latched relay you ground one side of the relay and you trigger the other side with the +12 volts. To make it a latching relay you put a jumper between the switched +12 and the side you are putting +12 to on the coil. This works because once the switch is closed and providing +12 volts it will basically be turning its self on. You then break the connection by disconnecting this jumper. You can disconnect the jumper with a simple 555 timer circuit or a capacitor driven timer. If you do a google search for 555 timer you can find many simple circuits to accomplish this. Just make sure you are aware you need to do it for a +12 volt system. You might be able to find a capacitor circuit that works better. This should be a very simple and easy to build circuit.

    Old Spark may chime in with the correct values and correct circuit.



    • #3
      I was faced with a similar issue and ended up using something called a cube timer. It was essentially a solid state time delay relay. It was made by NCC, the delay (how long the switch was closed) is set by a resistor between two leads on the cube. I think it cost around $25. I probably still have it in a box somewhere, I'll dig it out and see what it was. I was able to set it to close the relay for 3 seconds on energize of the cube.

      Edit: Wow, those things are damn expensive now.

      May be better off with redheadedrod's idea of building your own. $50 for a cube timer is a bit outrageous.
      Last edited by Tidder; 04-22-2014, 08:05 PM.

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      • #4
        I think this would be a good solution for you but with a larger cap say around 10000uf should give you about 3-6 seconds SNO