mr_byte31
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« on: January 08, 2008, 06:43:01 18:43 » |
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hi
i want to design a supply without using a transformer
the supply is 220/12
i thought to but a rectifier then a resistor then a zener 9v
what i want to know does the supply can supply much current
and is it stable
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Faros
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« Reply #1 on: January 08, 2008, 10:08:34 22:08 » |
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alliegro
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« Reply #2 on: January 09, 2008, 04:45:43 04:45 » |
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Transformer less power supply can provide upto(normally) 50ma of current. But be warned that there is NO ISOLATION. Also the regulation of the circuit is not very good. The mains power is taken through a capacitor (usually .47uf to 1uf) of atleast twice the AC mains voltage. Then the bridge rectifier of suitable rating as above,then the zener and capacitor at the output of the bridge. Usually the voltage is from 5V to 18V as desired by the Zener diode.
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irvinos
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« Reply #3 on: January 22, 2008, 08:02:54 20:02 » |
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Transformerless power supplies can be fatal. BTW the most important subject is current. How many current has been drawn?
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tantino
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« Reply #4 on: January 25, 2008, 04:32:37 16:32 » |
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Have a look at www.national.com or www.linear.com they have simple switchers and software tools that make power supply design so much easier |
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chen
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« Reply #6 on: February 14, 2008, 02:46:08 14:46 » |
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is it possible to increase the current capacity of the supply & how? |
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trapperxxx
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« Reply #7 on: February 21, 2008, 03:28:34 15:28 » |
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I never use this curcuit..but u want to more current, you must fly back..and transformer  ....I used lnk363pn 400mA in 5V and other channel 12V 100mA, everything is good .. and very little transformer ee16... |
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ambo
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« Reply #8 on: March 25, 2008, 05:52:07 17:52 » |
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Microchip has an application note for this ....powering up a pic mcu w/o any transformer or transformerless power supply. Cant remember the xact an number but just do a quick search for transformerless power supply in microchip website and youre sure to find it.
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sisar
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« Reply #9 on: April 02, 2008, 11:35:20 23:35 » |
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I found many industrial applications that use this type of transformerless power supply, like timers, but they tend to break very often, especially if u use a generator in case of power cuts or if there is a high noise on the line
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ekinci
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« Reply #10 on: April 03, 2008, 08:58:18 08:58 » |
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in a transformerless power supply maximum current you can get is around 200 mA
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pongsak.swf
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« Reply #11 on: April 04, 2008, 11:22:48 11:22 » |
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You use TOP221
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carlao
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« Reply #12 on: April 07, 2008, 03:37:14 03:37 » |
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Transformerless power supply can be done, until 50mA output. But, is important to keep same (or almost same) load in the output, to get some regulation in the output voltage.
If you deceide use SMPS, one option ins L6565N, from ST.
Posted on: April 07, 2008, 04:36:04 04:36 - Automerged
sorry: the L6565N use ans EXTERNAL mosfet.
For low power, use VIPer family, from ST.
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