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[b]I NEED HELP BUILDING A/V AB SWITCH WITH HEADPHONE JACK[/b

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by rlej1963, Jan 9, 2004.

  1. rlej1963

    rlej1963 New Member

    Joined:
    Jan 9, 2004
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    Location:
    Philadelphia, PA
    HAPPY NEW YEAR!!!

    I know this is a little long, but please read all as it will help to explain my delima. Thank You!

    I hope you can help me... I am a graduate of electronics school (back in 1984), however, I never really got to utilize any of the skills learned in electronics engineering technology. Instead, because I went to electronics school, I was hired to work with a large computer manufacturer - thus
    I am now the computer tech as opposed to the electronics tech... life is funny!

    Anyway, I do still know a little and with the right instructions I can find parts I need and even build the proper circuits to do the tasks I need done.

    This is where I hope you can help, guide, direct or etc.


    THE SCENARIO:
    I play video tapes for attorneys, judges and jury in a courtroom setting. The jury watches and listens to the A/V from the TV... I send the Video signal (via wireless 2.4GHz) to Attorneys table and to the Judge on the bench. While playing the tapes I am listening through a headset (headphones w/vol control) from the output on the back of the vcr. Additionally, this A/V output has to pass thru a A/V AB Switch so that I can stop A/V on all monitors (momentarily) while I am listensing and queuing in/out points via a transcript. LIVE EDITING is basically what I am doing. The attorneys want the jury to hear only testimony they feel is beneficial to their case. The rest of the A/V on tape I cut out by tapping the AB Switch at pre-determined in/out points.

    THE PROBLEM:As a videographer these days and I have a lot of video and audio gear needed to do my job for my clients. I've got this one issue that for (2) years I've just simply been working around. However, I believe I know what it is I need.

    When I am playing a VHS tape via VCR, I have a need to listen to the audio through headphones while simultaneously hearing audio at the tv (speakers). To accomplish this I plug a RCA to Mini 3.5mm adapter onto one of the (L/R) outputs of the vcr, which also has a piggyback rca cable attached so that the signal is split between my headphones and the tv.

    Well, needless to say that there are times (MOST ALL TIMES) that the audio at the tv is compressed, even if I turn the volume level on the headphones down completely and audio WAY-UP on tv - the audio at the tv is still compressed.

    WHAT I NEED or NEED TO BUILD/HAVE BUILT
    I need to build or retrofit either my AB Switch (A/V Line Level) or VCR with an audio (headphones) jack and if necessary have it be an amplified circuit. I know I am dealing with an impedence mismatch here. I currenty use an A/V AB Switch bought at Radio Shack for about $4 - $5.

    Can you help me? You would be a life saver if you can help me build a better A/V AB switch - complete with RCA A/V Jacks and even S-Video In/Out and with the ability to allow me to plug in my headphones and hear what is coming from VCRs A or B's audio out and, have it be heard at a level that won't affect the larger TV monitor being viewed by the audience.

    Please email me back with your thoughts or questions.
    I HOPE SOMEONE CAN HELP!!!

    Thanks in advance for any help or guidence you can provide.

    Rob - LEGALLY DIGITAL
    :? :?
     
  2. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

    Joined:
    Nov 17, 2003
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    Location:
    Derbyshire, UK
    It sounds like all you need is a headphone amplifier - where you currently split the cable to feed the headphones, feed a headphone amplifier instead. The high impedance input of the amplifier will prevent it upsetting the sound level of the TV.

    If it's all switched via your A/V box you could even build it inside.
     

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