RF transceiver / receiver module

Discussion in 'The Projects Forum' started by learningslowly, Oct 31, 2010.

  1. learningslowly

    Thread Starter New Member

    Aug 8, 2010
    5
    0
    Hello all and thank you for taking the time to read this and help me. I have a circuit that i pulled out of a LED strobe. It is a RF reciever for the matching key fob. The model number on the circuit is SR9915 V3.2 The circuit has 7 pins, theres a positive, a negative, one unused pin(I dont know what its for) and 4 output pins. Now my problem is that when the circuit is powered on the outputs are active negative, and when a LED is connected to +5v and the negative of the led is connected to one of the 4 pins the led will light up continuously until i hit the corresponding button on the key fob, it will then turn the led off as long as i hold the button down but when i let off the button the led lights back up. What i need is a circuit that will convert that closed circuit to an open circuit so the led will stay off when the device is on but when the button is pushed it will turn on and stay on until i hit the button again to turn it off. And i need to do this on all 4 channels. I used a LED just to explain but i will actually be using a transistor to power a relay on each channel. I want to be able to have the relay constantly off while the device is powered on but when the button is pushed the relay close and stay closed. Is there a circuit i can use to do this? I dont have a schematic for this since it was pulled from some chinese led strip but if it will help i can provide pictures and i will include a link to a page i found bout this chip. Thanks in advanced!

    http://translate.google.com/transla...r9915+rf&hl=en&rlz=1T4TSNB_en___US356&prmd=iv
     
  2. learningslowly

    Thread Starter New Member

    Aug 8, 2010
    5
    0
    I forgot to mention, if it is any help there is one main large IC on this circuit and its model is SC2272-M4.
     
  3. marshallf3

    Well-Known Member

    Jul 26, 2010
    2,358
    201
    Depending on how much LED current you need 4 units of a hex inverter IC will reverse the behavior and it can be used to drive small transistors f you need more current.

    The other way would be by using simple PNP transistors on the outputs.
     
  4. 5&under=sorcery

    New Member

    Jul 4, 2010
    28
    0
    The SC2272-M4 is a momentary contact unit, so that much of what you have is correct. I had a receiver that used that DIP just as you want it to so it is possible, but if your IC circuit that is driving the event can't be modified, will this work? You don't say what your voltage or power source is but if power consumption isn't an issue (not running on AA batteries or something similar) you could use a 2-pole relay that is always pulled in. You wire your transistor to the pole that closes upon button activation, the normally off. In other words, the relay is always ON but the switched circuit you need is available on the normally OFF side of the relay. If this is strictly low voltage DC via battery, this idea won't work due to the power consumption, but if you are taking your power initially from house mains or something like that the power consumption issue would be irrelevant.
     
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