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I have a clock that runs on 3 D batteries and, as you can imagine, it's a pain to maintain them. I've found a DC adapter that delivers 4.5v (1.5v x 3) but it doesn't budge when connected. I imagine there's some issue with amperage or resistance, but those aren't listed on the batteries! What should I be doing?

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closed as off-topic by PeterJ, Leon Heller, Matt Young, Daniel Grillo, JYelton May 28 '14 at 14:41

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  • "Questions on the use of electronic devices are off-topic as this site is intended specifically for questions on electronics design." – PeterJ, Leon Heller, Matt Young, Daniel Grillo, JYelton
If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Did you check the polarity of your adapter to see if it matches the batteries? Adapters can vary in the polarity wiring of their connectors. Also check that the adapter is actually working. A voltmeter would be very handy. \$\endgroup\$ – Barry May 28 '14 at 12:23
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    \$\begingroup\$ What sort of clock uses 3 D type batteries and needs them changing more often than once every ten years? I've got a clock on the wall in my office that runs from a single AA battery and has had one battery change in 7 years. It was already working before I started this job so who knows how many years it was ticking on the first battery - possibly 5 or 10. I'd be concerned about your clock and the 3 D types. \$\endgroup\$ – Andy aka May 28 '14 at 13:56
  • \$\begingroup\$ Also be sure to check out electronics.stackexchange.com/q/34745/2028 \$\endgroup\$ – JYelton May 28 '14 at 14:42
  • \$\begingroup\$ @Andy it has a ring of 72 bright LEDs. Actually the movement itself is powered by a single AA battery and is separate. \$\endgroup\$ – Isaac Lubow May 29 '14 at 10:23
  • \$\begingroup\$ Happy to delete this if it's off-topic. \$\endgroup\$ – Isaac Lubow May 29 '14 at 10:25
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There are a few possible problems.

  • Your power supply could be broken. Check it with a voltmeter. Jiggle the wires and make sure there's not an intermittent break somewhere.
  • Your power supply is actually putting out AC. Some wall warts are AC/AC. Does it say it puts out DC?
  • The batteries may be in parallel instead of in series, in which case you've already overvoltaged the clock's circuitry and may have destroyed it. Does it still work when you put batteries in?
  • Your power supply may not supply enough current to run the clock. That seems unlikely; clocks typically draw very little current. But you can check by seeing if the voltage on the output of your power supply collapses when you connect it to the clock.
  • You could have your polarity backwards. Make sure you've connected positive to positive, and negative to negative. Again, use a voltmeter.
  • You could have a bad connection. How are you connecting the adapter to the clock?
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