Advice: re-wiring vintage audio equipment

Discussion in 'The Projects Forum' started by James_SH, Mar 19, 2009.

  1. James_SH

    Thread Starter New Member

    Mar 19, 2009
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    Hi everyone,
    I'm working on an art project using lights, cassette players, and level meters salvaged from old stereo equipment, mostly from the 70s and 80s.

    I have no electronics background so will be learning everything as I go along. Below is my plan so far, and some questions. Any feedback and advice will be very welcome.

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    All the pieces will be mounted in a grid on a large board. There will be an input jack to receive a stereo signal. None of the pieces have to function as originally intended so I intend to rip out all the circuit boards and power supplies to cut down on weight. However, I'd like rewire them as follows:

    - For each piece that lights up, I'd like to replace the bulb with a new LED, and have all the LEDs in a circuit that can be controlled to light up in patterns, or to flash with the beat of the music, or at the very least be turned on and off with a switch.

    - For each piece with a level meter, I'd like to wire all the meters so they move with the beat of the music.

    - I'd like all the cassette players to turn (when the unit is on), but I'm wondering if this will be too hard to wire since each motor may require different power, and the entire sequence (about 30 players in total) may require too much power in total. I'd like to power them off of one 120V plug.

    ---

    Here are my questions so far:

    1. Is there a generic circuit board / controller unit that would power and control my sequence of LEDs?
    2. Is there a similar board that could trigger the meters to go with the beat of the music?
    3. Does anyone have a recommendation on how to make the cassette players turn?

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    Thanks for your time.
    Scott
     
  2. Wendy

    Moderator

    Mar 24, 2008
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    I sense troubled waters ahead. In addition to learning electronics, a lot of these old chunks of junk have a lot of mechanical stuff. If you have ever tried to rethread a tuner dial with new string you will know what I'm talking about.

    In addition, these classics will be using some older power supply technology. Not that it matters between old and new, but there WILL be some AC floating around, so be careful.

    If you have never messed with LEDs they are not direct drop in replacements, they are electronic devices in their own right, and need to have some understanding before they can be used properly. You can get background from almost anywhere, my contribution is this article.

    Good luck, Be safe, and Have fun!
     
  3. James_SH

    Thread Starter New Member

    Mar 19, 2009
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    Thanks for the initial advice, Bill. I've started reading the e-Books here in the forum, and hopefully in a few weeks I'll have enough of a background to start taking my stereos apart.

    In regards to the LEDs - I was never intending them to be drop-in replacements. Since the lights are one of the only things I really want to power in each component, I was planning to rip out the old power supplies, circuit boards, and everything associated with unnecessary parts (like the tuner dials, cassette players, etc.) Then, instead of figuring out how to power all the old bulbs, I was assuming it would be easier to take out the old bulbs and their wiring, and run a string of new LEDs in their place. So the new LEDs would be in the exact same place as the old bulbs, but they would have their own new power source and wiring.

    One more question I have before I start dismantling:

    The volume meters are the other devices I'd like to power, so I'm hoping to keep them whole and functioning if possible. I'm sure re-wiring them is going to be a complex task, but before I even get into that is there anything I should be careful of when removing other parts (like power supplies and circuit boards)? I'm assuming the volume meters are self-containted devices, and all I need to preserve are any wires running in/out of them. I guess what I'm asking is: can I safely remove all power supplies and circuit boards and still be confident that the volume meters will work if correctly re-wired and re-powered?
     
  4. CoolbeaN

    New Member

    Mar 26, 2009
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    I'm just as new to electronics as you are, so I may be way off here... But is seems to me that for what you are looking for, you can completely gut all of the equipment. If you are replacing the lights with LEDS that you want to all blink at the same time, it would seem simple enough just to run a series or sets of series amongst the units. And I'm sure someone here can help you with a circuit that will take a line level input from your audio device and vary voltage to the leds in time with the music.

    As far as the tape drives turning... it all comes down to a brushed motor at some point, so as long as you aren't particular about them all turning at the exact same speed, again a series or sets of series would work. A simple ac/dc adapter capable of ~7-10 Volts and 3-4Amps should work. It would not turn them in time with the music, but that would be hard to perceive anyway.

    Having all the gauges bounce would be a harder job though. You need to find some way to get each gauge a specific voltage range in which it operates. Edit: If you can get a volt meter on the poles to the gauge while it is in operation, you will know what voltage range each gauge operates in. If you are lucky some of them will be the same and that will simplify your wiring.

    BTW, I really like your idea. That's going to look awesome when you get it done. Are you going to use the same color LED's throughout or different?
     
    Last edited: Mar 27, 2009
  5. Wendy

    Moderator

    Mar 24, 2008
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    Yes and no. The VU meters are basically voltmeters, but they are calibrated. If you can identify the circuit and duplicate it they will work fine, but they probably will require a few resistors, diodes, and capacitors at a minimum, worst case maybe an amplifier. Audio is fundimentally a form of AC.
     
  6. James_SH

    Thread Starter New Member

    Mar 19, 2009
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    Bill:
    So you're saying I'll need to build a fairly detailed circuit for each meter? And you're assuming most or all will be AC?

    Theoretically, could I measure what each meter requires, then do all necessary calculations and build my own circuit board? I understand there are circuit Fabrication Labs that will print circuit boards for you based on your specifications.


    CoolbeaN:
    I'll look into some of your suggestions once I have a slightly better understanding of circuits. As far as the LED colour I was thinking whatever would produce a duller, vintage glow. Yellow, maybe?
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    Actually I was thinking if you could get schematics for some of this old stuff you could use them to make what you need. The circuit is pretty simple and straightforward, no need to reinvent the wheel.
     
  8. James_SH

    Thread Starter New Member

    Mar 19, 2009
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    I'm not sure where to find old schematics, but I guess I can start looking. I'm sure I won't be able to find all of them though. There are at least 30 or 40 meters.
     
  9. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
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    Don't you want to give some of your vintage equipment? I will pay for the shipping.
     
  10. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
    6,357
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    Depending on the brand of equipment, sometimes stepper motors to turn the reels, those are nowhere as simple to run as small brushed motors. You may want to count the number of wires coming out of the cassette deck motor.

    --ETA: "The Look" would be improved if you can find some of the cassettes that had the metal "reel to reel" look to them, two turning metal sprockets inside a clear plastic case, which hold the tape.

    Another nifty trick I've seen is to put surface mount "bar graph" displays by/beside/behind the sliders on an EQ, making a spectrum analyzer display. Big bonus points if it still functions as an EQ afterwards.
     
    Last edited: Mar 28, 2009
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