Relay suggestion for my project

Discussion in 'The Projects Forum' started by AutoLuxLexES, Jan 20, 2013.

  1. AutoLuxLexES

    Thread Starter New Member

    Jan 20, 2013
    3
    0
    Hello all,

    I am working on a bluetooth project. I plan on hardwiring a bluetooth receiver to a factory stereo to keep that simple original look. I was talking to a professor the other day about suggestions for relay( circled in red), and he suggested that I use a solid state relay. In my search for one, I cannot seem to find anything that fits my needs. I would like to go with a SSR as it should be smaller than an automotive EMR. Please recommend one for me.

    A little about the project. original source will be 12V, with a 5 volt regulator to power 2 usb female receptacles. 1 usb(usb at top of pic) will be for charging or whatever, but the second usb(bottom of pic) will be connected to the bluetooth receiver. The plan is to take a 8.3V signal when the tape button is pushed to activate the relay and power on the second USB. So pretty pretty much when i press tape button, bluetooth will turn on, if the tape button is not pressed, the bluetooth will be off.

    As for the LED, online resistor calculator suggest that I use 1/8W 150ohm resistor, but I can get 1/4W 150ohm resistor from school. Can I use the 1/4W resistor instead of 1/8W?


    [​IMG]


    Thank You,
    Charley
     
    Last edited: Jan 20, 2013
  2. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,769
    969
    Is the tape button momentary?

    and yes its never a problem to use a higher wattage rated resistor.. It will just run cooler. I always multiply the required wattage x 2 for a safety factor
     
  3. AutoLuxLexES

    Thread Starter New Member

    Jan 20, 2013
    3
    0
    Hello Mcgyver,

    Yes, I believe the tape button is a momentary switch or a sort of momentary switch because if i press the CD/FM button, the tape player will shut off, but that may be because of circuitry design.

    Charley
     
  4. atschirner

    New Member

    Jan 23, 2013
    2
    0
    You can replace the relay with a correctly rated SCR. Even if your trigger signal is momentary an SCR will continue to conduct until the incoming power is removed. I'm guessing that would happen when you turn the key off. If you need a device that follows the incoming signal on and off go with a N channel FET in the ground side of your USB connector. Good luck, AT
     
  5. AutoLuxLexES

    Thread Starter New Member

    Jan 20, 2013
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    0
    Im not familiar with what an SCR is. I am going to search around for now, but could you please shed some more light on this SCR?
    My professor did also recommend an N channel MOSFet, but said that I should stick to SSR since it will be easier. I am in no way an electrical person, but I do try to learn and perform my own projects the best that I can, especially when it's something that I haven't seen many others do.

    Thanks
    Charley

    BTW, Mcgyver, are you on hidplanet?
     
  6. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    969
    No not on hidplanet.. Thats just someone pretending to be me ;)

    Wikipedia has all the information you should need on an SCR/SSR,etc..

    Do you need latching? Or do you really want it that when you are holding down the tape button the USB is on. As soon as the button is released the USB will turn off?
     
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