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Kai Klaas
03/27/12 17:03
Modified:
  03/27/12 17:06

Read: 764 times
Germany


 
Msg Score: +1
 +1 Good Answer/Helpful
#186923 - Capacitor power supplies...
Responding to: Chico Magalh„es's previous message
Chico said:
I know about all danger in this, I dont need an alert.

Then why the bloody hell are you toying arround with it??? Chico, this isn't a game but real life! You were not the first man being hurted or even killed by mains voltage, believe me...

Here is a link explaining capacitor power supplies in more detail:

http://ww1.microchip.com/downloads...00954A.pdf

Read it carefully, especially the chapter "safety considerations". What is shown there is not a "nice option" but in most countries a MUST. So, you NEED a fuse, you NEED R1 and you NEED R2. Also, R1 and R2 MUST be surge proof, i.d. they must be able to withstand surge voltages of several thousands of volts. Also, C1 MUST be an X-cap! D1 MUST also withstand inrush and surge currents, so, you would not use a simple zener diode but a ROBUST TRANSZORB or TRANSIL, which quits an overload by a short circuit and not open circuit!!

VR1 is critical. Varistors were widely used in the passed. But overloads often resulted in an increase of leakage current and one fine day the varistor became so hot that it started to burn. Many fires occured because of an overheating varistor. Also, during surges a varistor tends to explode. So, today, when using a varistor, it NEED to be mounted with a temperature fuse and the ambient NEEDs to be protected against eventual explosion.

Kai Klaas

List of 26 messages in thread
TopicAuthorDate
555 Timer for AC      Chico Magalh„es      03/23/12 15:42      
   "a circuit I got in the internet..."      Andy Neil      03/24/12 00:44      
      Tests      Chico Magalh„es      03/24/12 01:25      
         Then leave AC mains well alone!!        Andy Neil      03/24/12 05:11      
         then why did you put it together        Erik Malund      03/26/12 06:57      
            a recipe for disaster        Andy Neil      03/26/12 12:38      
               How safe is safe?      Justin Fontes      03/26/12 13:51      
                  HUMANLY safe      Erik Malund      03/26/12 13:57      
                     I would also add      Justin Fontes      03/26/12 14:21      
                        A good link to electrical safety      Justin Fontes      03/26/12 20:28      
   You dally with danger again!        Kai Klaas      03/24/12 06:58      
   the value of a human life ....      Erik Malund      03/26/12 13:02      
      An unsafe bodge for a basically unsuitable design!      Andy Neil      03/26/12 13:24      
   So this circuit cant work?...      Chico Magalh„es      03/26/12 22:03      
      How much do you understand?      David Prentice      03/27/12 01:07      
      How do you know you know enough?      Per Westermark      03/27/12 01:16      
      already answered      Erik Malund      03/27/12 06:09      
      Capacitor power supplies...        Kai Klaas      03/27/12 17:03      
         the bane of the high voltage amateur      Erik Malund      03/28/12 07:03      
            Just 24V isn't enough      Per Westermark      03/28/12 07:53      
      You are contradicting yourself!      Andy Neil      03/28/12 14:11      
   RE: 555 Timer for AC        Hans Van Pelt      03/27/12 02:48      
      Triacs      Andy Neil      03/28/12 14:08      
   I'm giving up        Chico Magalh„es      03/28/12 21:25      
   Re      Ramesh Rai      04/18/12 21:03      
      Don't hijack threads      Andy Neil      04/18/12 23:14      

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