230Vac to 12 Vdc???
230Vac to 12 Vdc???
(OP)
I need to convert 230Vac to 12 Vdc using the minimum material possible, which means no transformer.
The rectification of the 230V wave doesn't have to be perfect because i will need the 12V to connect a relay and a CD4013 flip flop.
Best regards, Carlos Cardoso
The rectification of the 230V wave doesn't have to be perfect because i will need the 12V to connect a relay and a CD4013 flip flop.
Best regards, Carlos Cardoso






RE: 230Vac to 12 Vdc???
RE: 230Vac to 12 Vdc???
Try this:
_____| |_______|\|_______________
| | | |/| | +
C2 | D2 |
230VCA _|_ |+
D1 /_\ ----- 12VDC
| ----- C2
___________|___________|_________-
C2= 1,5uF 275Vca (polipropileno)
D1= 1N5349 (diodo zener )
D2= 1N4007
C2= 470uF 25V (eletrolitico)
Regards,
M3
RE: 230Vac to 12 Vdc???
| | | |/| | +
C2 | D2 |
230VCA _|_ |+
D1 /_\ ----- 12VDC
| ----- C2
________|___________|_________-
RE: 230Vac to 12 Vdc???
RE: 230Vac to 12 Vdc???
This method works but is very inefficient: compare power in to circuit compared with power delivered to the load. Capacitors are cheap and don't dissipate real heat (just imaginary heat
RE: 230Vac to 12 Vdc???
BEWARE: Any no-transformer solution you attempt here will obviously not be isolated from the power source. Translation: DANGER WILL ROBINSON! DANGER! You should SERIOUSLY consider a transformer if for no other reason than power line isolation. I'd strongly suggest you reconsider your requirement to eliminate the transformer.
Have you considered using a plain-old wall-wart transformer? Those things are practically free, plus you get the very desireable POWER LINE ISOLATION as previously mentioned.
RE: 230Vac to 12 Vdc???
Oh yeah -- A better SCR circuit might use an RC voltage divider as the trigger -- this is really more of a phase angle controller, gotta bust out the vector calcs for this one.
DANGER DANGER DANGER
For real down and dirty, just use a resistance voltage divider fed into a diode, use that to charge a cap. You'd only want to use this for very very low power levels.
DANGER DANGER DANGER
RE: 230Vac to 12 Vdc???
RE: 230Vac to 12 Vdc???
RE: 230Vac to 12 Vdc???
I agree this kind of thing goes against everything your instinct tells you, but these circuits are frequently used: the lighting dimmer on a wall being a prime example, as are some of the electronic ballasts used with fluorescent tubes.
When used in a carefully considered design, they are a useful means of providing small amounts of power cheaply when the application does not require isolation, or where isolation is provided by some other means. The safety aspect depends heavily on the application, and on specification of components designed for service on the mains.
As RAMconsult says, unless you are very sure what you are doing when designing a supply for direct connection to the line, let someone else do it and buy it from them.
RE: 230Vac to 12 Vdc???
I agree that isolation should be provided but on many occasions it is not. Whether or not it is safe is another story and can only depend on the whole design and what function it plays. Trying to use a voltage divider for 230VAC is difficult due to heat. I have done it but the device was only rated for 40C and I was not proud of it, heat kills.
RE: 230Vac to 12 Vdc???
RE: 230Vac to 12 Vdc???
But before you even do that, search this site for VOLTAGE DROP. This question has come up MANY times lately within the last few weeks, and several replies have been posted with links to free voltage drop calculators.
Please check out FAQ731-376 for additional information.