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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? _________________ Jason the elite |
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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? _________________ 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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