Any scheme that derives low voltage from the mains without use of an
isolating device should only be used in volume production by a competent
designer / manufacturer, if then. About the only reason to do this is low
end cost and/or compact size. System which fall in this category include
series capacitor, series resistor and electronic switches which turns off
when mains voltage rises above a given level.

- All versions of this sort of system can and will kill people.

- All parts of the circuit are potentially at mains potential.
- Component failure of several sorts can change the "potential" to "actual".
- Doing this on a one-off or amateur basis lacks the controls needed to give
you half a chance of not killing someone.

- Very small iron mains transformers are available at lowish cost.
- Use of switching regulators and high frequency transformers allows very
small size.



regards,



      Russell McMahon
_____________________________

What can one electrocuted man* do?
Avoid the pain and help the hungry at no cost to yourself!
at  http://www.thehungersite.com/
(* - or woman, child or internet enabled intelligent entity :-))
From other worlds:
www.changingourworld.com    www.easttimor.com   www.sudan.com


-----Original Message-----
From: Thys Van Tonder <thys@CENTSYS.CO.ZA>
To: PICLIST@MITVMA.MIT.EDU <PICLIST@MITVMA.MIT.EDU>
Date: Monday, 18 September 2000 19:02
Subject: Re: [EE]: 5V DC from 220V AC supply without a transformer?


>Hi Francois
>
>You can look on the Microchip web-sight. There are some nice App. notes on
>transformer less power supplies.
>Look in the 12cXXX section.
>
>Regards
>
>Thys
>
>
>
>-----Original Message-----
>From: pic microcontroller discussion list
>[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Francois Robbertze
>Sent: 15 September 2000 04:22
>To: PICLIST@MITVMA.MIT.EDU
>Subject: [EE]: 5V DC from 220V AC supply without a transformer?
>
>
>Someone told me a while ago that I can do without the expensive
transformer,
>diode bridge and regulator to get  5V power from a 220 - 250V AC line to
>drive a PIC with some other components like a relay, triac, leds etc.
>
>I remember them talk about caps and zeners..
>
>(I am use to the XFormer and the well known 78L05 method)
>
>Can sombody help me with a plan
>
>Kindest Regards
>
>
>              lllllllllll
>             \\  ~ ~ //
>             ( @ @ )
>o------oOOo-(_)-oOOo-----o
>|                                   |
>|   Francois Robbertze    |
>|    fr10@mweb.co.za     |
>|                                   |
>o--------.oooO-Oooo.-------o
>
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