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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB
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 Posted: Fri Nov 23, 2007 11:36 pm Post subject: Transformerless 5 Volt Power Supply |
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http://www.electronics-lab.com/blog/?p=510
http://www.josepino.com/circuits/index?transformerless_power_supply.jpc
"Simple, low cost and easy to build power supply. Ideal for applications that doesn’t require too much power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the circuit is in contact with the user. The voltage supplied by this is determined by the zener diode." |
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ginbot86
HG Contributor
Joined: 02 Aug 2008
Posts: 47
Location: Canada
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| Posted: Wed Aug 13, 2008 9:31 pm Post subject: |
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Wow. So, you'll get shocked if you're in contact with the low voltage side of the circuit?
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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB
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| Posted: Wed Aug 13, 2008 11:07 pm Post subject: |
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| ginbot86 wrote: | | Wow. So, you'll get shocked if you're in contact with the low voltage side of the circuit? |
You are correct.  These should only be used when there is no chance of anyone coming contact with the output. It is very cheap to go this way since the transformer is usually a big expense of the power supply. |
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ginbot86
HG Contributor
Joined: 02 Aug 2008
Posts: 47
Location: Canada
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| Posted: Thu Aug 14, 2008 12:17 pm Post subject: |
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So, the equipment connected mustn't touch ground then?
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Jason the elite |
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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB
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| Posted: Thu Aug 14, 2008 10:36 pm Post subject: |
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| ginbot86 wrote: | | So, the equipment connected mustn't touch ground then? |
That's right. |
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electron
Semi Newbie
Joined: 30 Mar 2009
Posts: 8
Location: UK
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| Posted: Wed Apr 01, 2009 12:40 am Post subject: |
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| Alan wrote: | | ginbot86 wrote: | | So, the equipment connected mustn't touch ground then? |
That's right. |
Ah well, I remember the days when all the electronic shops were flooded with mains transformers for high voltage secondrys. But there are plenty of stepdown transformers on the market now. |
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Alexander125
HG Master
Joined: 13 Jan 2009
Posts: 105
Location: Galati, Romania
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| Posted: Wed Apr 01, 2009 11:27 am Post subject: |
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i didn't see the transformer, so if you put a 110 volt zener u get killed.
nice
a stepdown transformer costs under 2 or 3 bucks for 500 miliamps.
better not take the chance.
i stick to transformers |
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Alan
Site Admin
Joined: 29 Jan 2006
Posts: 1399
Location: Winnipeg, MB
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| Posted: Wed Apr 01, 2009 1:19 pm Post subject: |
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| Alexander125 wrote: | i didn't see the transformer, so if you put a 110 volt zener u get killed.
nice
a stepdown transformer costs under 2 or 3 bucks for 500 miliamps.
better not take the chance.
i stick to transformers |
This would make a great solution for a project that needs to connect directly to AC power and need to be very small. It would need to be in a sealed case so that no one could ever come in contact with it. |
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Alexander125
HG Master
Joined: 13 Jan 2009
Posts: 105
Location: Galati, Romania
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| Posted: Fri Apr 03, 2009 12:06 pm Post subject: |
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yes, you are wright, but I dont really want to go that way.
Simply buy a transformer, a diode rectifier bridge and you're set. |
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tbyte
Newbie
Joined: 13 Jul 2009
Posts: 2
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| Posted: Mon Jul 13, 2009 10:31 pm Post subject: |
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| You can find plenty of 5v supplies for 3 bucks or so commercially. They are used for recharging MP3 players, phones, and other devices that have USB connections. |
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