Need help making a line in cable

Discussion in 'General Electronics Chat' started by derk, Jun 17, 2009.

  1. derk

    Thread Starter New Member

    Jun 17, 2009
    2
    0
    Hello,

    I need to fabricate a cable where I can run a signal from an PA system OUTput to a microphone input. Its a Panasonic BB-HCM381A network cam and a older PA system, which I assume will have an RCA style output jack.

    Panasonic tech support would only tell me I that I needed to make a cable with an IN LINE RESISTER, a 3.5mm connector and an RCA connector.

    My questions are:

    1. What kind of resistor do I use? Type, model etc? What I would need to know going to a store and asking for one.

    2. How do I figure out which wire of the two wires do I add this resistor to?
    Do I need to attach the resistor to so that one end is connected to a particular end of the cable? Or does it not matter how I insert the resistor into the line of the cable?

    Thank you:)
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You need to pad the signal level down to a microphone level. This sounds kind of kludgy - can you get at the input signal to the PA amp? - it's lots closer to the microphone level. Especially if the PA amp is a 70 volt type.
     
  3. derk

    Thread Starter New Member

    Jun 17, 2009
    2
    0
    Excuse my lack of understanding, I'm not familiar with words like "pad".

    Are you saying that perhaps I should find where the mic signal is going into the PA system and use that signal to go into the webcam?

    Thank you:confused:
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    That approach would possibly be better. The signal level would be predictable, unlike the PA output that would vary with the gain setting. It is hard to predict success without knowing the type of input the webcam expects.

    There are several types of microphone with different output levels. The camera probably expects a microphone input, though, and you may get lucky and have the "right" one.

    Padding a signal means reducing its magnitude, usually with resistors.
     
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