AA current - wire testing for current

Discussion in 'General Electronics Chat' started by Current -Ly dumb, Oct 13, 2016.

  1. Current -Ly dumb

    Thread Starter New Member

    Oct 13, 2016
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    Hello, I have a new hobby which is buying and selling vintage super 8 cameras, I can take them apart and fix them but the only time I have issue is when it comes to finding the source of the problem when it comes to if the motors are getting power, or if they are not. I know the at the power source , in this case the 4 aa batteries in the camera is good as the battery tester built into the camera shows it, now I need to track down the issue that I cannot see within the camera after checking all the solder connections.

    Is there a tool I can use that I can simply touch the exposed wire connection at a solder point to determine if the current is active at that particular point?

    Thanks Kirk
     
  2. dl324

    Distinguished Member

    Mar 30, 2015
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    Welcome to AAC!

    I have used an HP5487A current tracer to do that. That probe doesn't require exposed wires to detect current.
     
  3. wayneh

    Expert

    Sep 9, 2010
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    A lightbulb on a wire?
     
  4. Current -Ly dumb

    Thread Starter New Member

    Oct 13, 2016
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  5. Current -Ly dumb

    Thread Starter New Member

    Oct 13, 2016
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    Thank you for your help! I appreciate it.

    Kirk
     
  6. Current -Ly dumb

    Thread Starter New Member

    Oct 13, 2016
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    Can you elaborate please, thanks.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    Any spot with enough power for the motor would also light a small bulb. I'd be a little nervous about it, though, since it would be like shorting to ground if you touch a sensitive spot.
     
  8. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
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    A multimeter (voltmeter)...
    I suspect you really mean is there voltage at that point not current (yet).. A voltmeter will easily tell that..
     
  9. Current -Ly dumb

    Thread Starter New Member

    Oct 13, 2016
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    Yes you are correct and thank you!
     
  10. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    A modern digital multi-meter can help you tremendously, far more than a batter and a light, and for about the same price too.

    They make three basic measurements: voltage, resistance, and current. Current is probably of no use to you but voltage will tell you if batteries are good, and also can help find breaks in wires or switches. Resistance is great for measuring wires to see if they connect (best to take the batteries out first).

    The very first hit I got on EBay for searching "digital multimeter" was a $8.98 meter in CA that would be fine for your needs. It even comes with decent leads and a battery. This unit also has a beeper feature you can use as a quick test for continuity (good connections). Some of the feedback says the volume is low so you may want to choose a better unit. (Probably most every regular on this board has spend way more than that for their meter.)
     
    Last edited: Oct 16, 2016
  11. wayneh

    Expert

    Sep 9, 2010
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    I agree completely on the bang-per-buck of a multimeter, but there are still situations where the lightbulb load technique is useful. It requires current to light the bulb. A corroded wire in an automotive environment may be able to pass a few microamps to show an in-spec voltage on a multimeter, but not when loaded by the bulb.

    Of course placing a 1K resistor across the voltmeter leads would accomplish much the same thing.
     
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