A small simple circuit to get 5 volts from 230 volts mains.

Discussion in 'General Electronics Chat' started by simmi, May 9, 2016.

  1. simmi

    Thread Starter New Member

    Dec 29, 2009
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    Hi.
    Summer is approaching and my fan has finally been taken out from its resting place. Which reminded me that I have always wanted to make it wireless.
    It runs from the mains so it uses 230 volts.

    I would like to know if there is a simple way to get 5 volts from the mains 230 volts to power the peripherals I need to make it wireless. This would most likely be an Arduino chip connected to a Bluetooth module. So I would require 5 volts and something like 100mA making 0.5W.

    Smallest and least complicated design wins! :D

    Cheers!
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    But a wall wart. Just one part (for you), and extremely cheap.

    John
     
  3. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Not only cheap, but free. Check with your friends. They probably have some laying around in a junk drawer. I get mine from a thrift store for $0.75US...5VDC/2.0A

    Ken
     
  4. WBahn

    Moderator

    Mar 31, 2012
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    I agree -- a wallwart is definitely the least complicated (from your perspective) and almost certainly the cheapest. It may or may not be the smallest, but they aren't very big so it should be small enough.

    Do NOT build a transformerless power supply if you run across the design for one. My guess is that you probably lack the experience to work with these circuits safely and you don't want to go poking around your 5 V circuitry only to find yourself tangled up with 230 VAC.
     
  5. simmi

    Thread Starter New Member

    Dec 29, 2009
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    When you say "wall mart" I assume you mean an already produced power supply that is plugged into a wall socket and provides a different voltage. In this case 5 volts.
    If so, then that is exactly what I am trying to avoid.
    I would like the electronics to be inside the fan's casing.

    I agree with you that that is the easiest solution though. But not what I want. Unless it is small enough to fit inside the fan housing and I can "plug it in" the mains inside the housing. Hmm. I have not thought of that before :) Might be viable if I find a super small power supply.
     
  6. WBahn

    Moderator

    Mar 31, 2012
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    Depending on how much room you have inside the casing, you may very well be able to put the body of the wallwart inside it. You probably want a corded unit so that you can cut the cord and splice it into the fan's cord. Be sure to take into account any polarization of the cord when you do so.
     
  7. #12

    Expert

    Nov 30, 2010
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    We see a lot of this. It sounds something like, "I saw one, therefore I must have the education, skills, and test instruments required to build them better, faster, and cheaper." Sorry, pal. Those days are over.
    In 1950, anything a man could build, a man could fix. It just isn't true now. There are thousands of things so far advanced that you could pick any 5 and the smartest person you can find couldn't repair most of them. High frequency power supplies are an excellent example of turning me into a dinosaur. I can still do bloody wonderful things with an analog power supply design, but out-classing a high speed switcher isn't one of them.
     
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  8. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    That was going to be my suggestion. An iphone charger clone is small and cheap. If you don't have room for the receptacle end of an extension cord, solder the line cord wires directly to the AC plug pins. Important: cover the connections with shrink tubing, preferably two layers of it on each pin. This is what I travel with instead of a USB male-female extension cable. 10 feet long, can reach far-away airport wall outlets, cost pennies. Geek travelers envy me.

    ak
     
  9. simmi

    Thread Starter New Member

    Dec 29, 2009
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  10. tcmtech

    Well-Known Member

    Nov 4, 2013
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    That would work just fine.

    Or you could just crack open an old USB adapter and use its circuit board for free.
     
  11. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I gut wall warts frequently. The only problem I have is how to mount them. Components are mounted to the very edges of the PCBs. You have to be creative. ;)

    Ken
     
  12. tcmtech

    Well-Known Member

    Nov 4, 2013
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    RTV silicone.
    Or
    Two part epoxy if you are in a hurry.
     
  13. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    If its a 5v smpsu you're after, an old nokia or mobile phone charger will do...crack one open..
     
  14. BR-549

    Well-Known Member

    Sep 22, 2013
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  15. ErnieM

    AAC Fanatic!

    Apr 24, 2011
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    What is a wireless fan?
     
  16. tcmtech

    Well-Known Member

    Nov 4, 2013
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    Used to be an open window.
     
  17. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
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    Wouldn't the mains cord be a wire?
     
  18. Picbuster

    Member

    Dec 2, 2013
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    One chip, plus some low cost components , is doing this. Its the lnk304gn.
    However no mains separation so be careful.
    Picbuster
     
  19. tracecom

    AAC Fanatic!

    Apr 16, 2010
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    In addition to being against the TOS, an lnk304gn, 6 resistors, 5 diodes, 1 inductor, 6 capacitors, and 2 transistors plus a PCB isn't a simple power supply by my definition.
     
  20. dannyf

    Well-Known Member

    Sep 13, 2015
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    that's easy enough: find a 5v converter that's small enough to fit into your fan or find a fan that's big enough to house your 5v converter.
     
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