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Internal to External Microphone Switch-over + remote focus and shutter control
  • I've been hunting through the net and found a simple circuit that will act as a remote for the GH2. It effectively emulates a half press and a full press.

    The circuit is here:

    However I find that with this, the external microphone is not enabled. I've been wondering if this is something a firmware hack could address or do I have to modify the circuit further.

    Listening to some test clips back it seems that the external microphone is contributing a little when the 'half press' button is operated, leading me to think that the mics are getting mixed through resistance.

    A possible experiment is to change the resistance between pins 3 and 4 to work out at which point it decides that the external microphone should be used.

    My application is a thumb operated remote on a 'FigRig' mounted GH2 with hopefully a Rode Video mic giving me more directional pickup.
  • 4 Replies sorted by
  • Did i understand it correctly, that there is an adapter to be able to use a remote AND an external microphone with the adaptor mentioned?

    Do you know where to buy the adaptor?
  • OK, so this morning I took apart a remote and substituted the resistance values until I observed various results.

    So, taking the resistance between pins 3 and 4 (i.e. the furthest from the tip of the 2.5mm connector) I found:

    50-40K --- the GH2 knows that there is an external remote
    10-4K --- the GH2 sees a 'half press' and initiates auto focus if an autofocus lens is attached, if not the 'QMenu' disappears from the screen.
    2.5-1.8K --- if you enter this value momentarily the GH2 will start recording
    330R - 0R --- the GH2 enables the remote microphone

    Further Experiments

    From To Result
    Open 2K Nothing
    Open 120R External Microphone Enabled
    4K7 2K Nothing (didn't expect this)
    47K 2K Starts recording
    2K 120R When Recording - Nothing :(
    2K 120R When Idle - External Microphone Enabled

    Therefore I deduce the following logic.

    a) For the remote function to work, the GH2 has to see around 47K before it will recognise any button press.
    b) For recording to start there must be a transition from a higher resistance to around 2K
    c) The external microphone can only be enabled from Idle (i.e. this cannot happen whilst recording)

    I therefore, therefore conclude that we'd need a firmware change to get the external microphone and remote functions to operate simultaneously.


  • is there any progress for this solution?

  • @Vitaliy is there any firmware options for remote and mic?