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jjrush
New Member
USA
2 Posts |
 Posted - Jul 12 2011 : 7:15:16 PM
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| I am new to the forum and I know just enough about electronics to pull parts and solder them in the right order. I found this schematic (http://www.aaroncake.net/circuits/supply5.asp) and need some advice. I need to get the current up to about 100 mA. Can that be done just by changing out the caps? Can anyone help? |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Jul 13 2011 : 10:07:01 AM
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| You could increase the value of the capacitors a few hundred times but then they would be larger and cost much more than a normal little transformer. The zener diode also must be huge and expensive. |
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wasssup1990
Nobel Prize Winner
A Land Down Under
2261 Posts |
Posted - Jul 13 2011 : 10:52:19 AM
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I wouldn't recommend anyone build this power supply. It lacks an important safety feature - Galvanic isolation.
Proper power supplies that meet your requirements are electrically isolated from the main high-voltage power supply with the use of a small, low-power transformer.
I don't have any schematics for you, sorry. Apple makes small USB iPod/iPhone chargers and I have got one. I haven’t opened mine up, but other people have and it is quite a bit more complicated than Aaron's schematic, with good reason. Apple doesn’t want to run the risk of electrocuting or killing people and they also don't want their chargers to wreck their own products when things go wrong.
This thread may be worth a look at:
http://electronics.stackexchange.com/questions/12550/how-can-i-duplicate-apples-tiny-usb-power-adapter
Good luck. |
When one person suffers from a delusion it is called insanity.
When many people suffer from a delusion it is called religion. |
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jjrush
New Member
USA
2 Posts |
Posted - Jul 14 2011 : 8:38:38 PM
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| Thanks for the help. I will abandon this and find a better way. |
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theresa
New Member
Philippines
2 Posts |
Posted - Nov 29 2011 : 8:04:18 PM
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| what is the advantage of having a transformer less power supply compared to a power supply with transformer? |
Godbless..:DD |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Nov 30 2011 : 11:58:47 AM
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quote:
Originally posted by theresa
what is the advantage of having a transformer less power supply compared to a power supply with transformer?
A plug-in night light does not have a big, heavy and expensive transformer so it is small, lightweight and inexpensive. |
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theresa
New Member
Philippines
2 Posts |
Posted - Dec 01 2011 : 09:52:07 AM
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| thank you for your answer mr. audioguru...and yeah i know that it is inexpensive and lightweight but what are other advantages aside from those? |
Godbless..:DD |
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audioguru
Nobel Prize Winner
Canada
4218 Posts |
Posted - Dec 01 2011 : 9:33:14 PM
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quote:
Originally posted by theresa
.....what are other advantages aside from those?
I told you the advantages. Why do you want more?
It is a simple stupid night-light. |
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Aaron Cake
Administrator
Canada
6718 Posts |
Posted - Dec 03 2011 : 10:34:38 AM
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quote:
Originally posted by theresa
what is the advantage of having a transformer less power supply compared to a power supply with transformer?
Becuase it is compact. So if very little current is required, thereis no need for any kind of bulky transformer, PWM stages, etc. For example, in the IR Switch schematic on this site, a similar circuit is used to power the receiver, keeping it small enough to be tucked into a light switch box. |
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Transformerless power supply
