So what can I do to have 5-10A 12vdc without transformer? I need some switching power supply circuit does anyone saw on the 'net simple switching PSU circuit? I know I have to do some coil stuff, but it worth it. Helllllpppppppppp Tal -----Original Message----- From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of Joris van den Heuvel Sent: Friday, December 28, 2001 3:02 PM To: PICLIST@MITVMA.MIT.EDU Subject: Re: [EE]: is it really DC? I think the output is in no way a nice sine wave. The RMS output is 12 volts, but if you would rectify it, I think you'll get at least double that voltage. Those simple halogen transformers usually just chop up the mains AC voltage with a few kHz. The effective frequency is now much higher than the mains frequency, though it's still in there! Because of the high frequency the transformer core can be small and cheap. A chopper circuit costs less than a buck. A large transformer costs a few more ;-). The AC coming out would look something like this on a scope: _ _ _ | | | | _ _ | | | | | | | | _ _| |__| |__| |__| |__| |__| |__ __ __ __ __ __ __ etc. |_| | | | | | | | | |_| |_| | | | | |_| |_| |_| ----- Original Message ----- From: Tal Bejerano - AMC To: Sent: Friday, December 28, 2001 11:05 AM Subject: Re: [EE]: is it really DC? > Hi Peter > > Are you sure about that I cannot regulate the 12v? > the transformer output on the pcb look like not connected to any device > neither resistor or capacitor for current feedback. > or maybe the feedback is on the primary coil? > if I draw it's circuit, should it help you see if I can use it? it's very > simple circuit some capacitors and resistors and 2 transistors. > > Thanks > > Tal > > > > -----Original Message----- > From: pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU]On > Behalf Of Peter L. Peres > Sent: Friday, December 28, 2001 9:11 AM > To: PICLIST@MITVMA.MIT.EDU > Subject: Re: [EE]: is it really DC? > > > You can't use that transformer as you want, it only works with a normal > bulb (halogen or not), or other resistive load. This is because it uses > current feedback and a saturable core transformer. > > The output is insulated at least in theory, because halogen fixtures are > not rated for mains voltage. Check for compliance marks (EC/GS/TUV etc). > However you get to use this only at your own risk ;-). > > Peter > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads