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Power supply - Importance of amp Rating?

  1. Feb 1, 2010 #1
    Power supply -- Importance of amp Rating??

    Hello all: I have a TV tuner that requires a DC 7.5 volt, 500 ma power supply. I have a 110 V input power supply rated at 7.5 V DC 1,000 ma. Can I safely use this powersupply with the tuner. Analogy: I can plug a 3.5 am vacuum cleaner into a 15 amp circuit and know that on this 110V A/C circuit, the amperage means that you cannnot simultanously plug in devices collectively drawing more than 15 amps. Likewise, can I safely plug in a 7.5 v 500 ma device into a 7.5 v 1000 ma circuit, and not risk eventual burn-out? An electrician tokld me the tuner would eventually burn out, although it is running fine now. Is he right?
  2. jcsd
  3. Feb 1, 2010 #2
    Re: Power supply -- Importance of amp Rating??

    A tuner drawing 500 ma at 7.5 volts dc can run safely on a 7.5 volts dc, 1000 ma supply. Bob S
  4. Feb 1, 2010 #3


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    Re: Power supply -- Importance of amp Rating??

    I would assume that the TV tuner requires a smooth DC source such as from a battery. I don't know what your 7.5V 1000mA supply consists of, but it should probably not be a wall-wart type supply since that would likley produce alot of ripple voltage instead of a nice smooth DC supply. Your assumption which compares the vaccuum cleaner in a residential 15 amp circuit is correct. I hope that the 'electrician' is simply someone who calls himself that. I wouldn't take any advice from someone who tells you this.
  5. Feb 1, 2010 #4
    Re: Power supply -- Importance of amp Rating??

    The power supply is rated to supply up to 1000mA therefore it can supply any amount of current up to 1000mA. You only need 500mA of power so you will be OK. The important thing is that the voltage is the same and therefore you should have no problems.
    http://www.calibrepower.co.uk" [Broken]
    Last edited by a moderator: May 4, 2017
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