I need help to develop a power supply

[paulopca]

Hello to all!

I need help to develop a power supply that is capable of receiving the input 12Vdc or 9VAC rms and delivered to the output +12 Vdc and -12Vdc with capacity of up to 8W of power.
Attached is the circuit I'm trying to use and need to determine the values of the components.
If anyone has a better suggestion for a circuit that does not need transformer to generate the positive voltage and negative and use in place of the transformer capacitors shall be very grateful to anyone who can day provide.
Thanks to everyone who can help me.

Best regards
Paulo

 

[tpetar]

If anyone has a better suggestion for a circuit that does not need transformer to generate the positive voltage and negative and use in place of the transformer capacitors shall be very grateful to anyone who can day provide.

Psu without transformer hardly can be called better suggestion.

What you mean under "transformer capacitors" ?

 

[yogece]

i have seen your circuit diagram.but where is the regulator even if you put a regulator for +12V it work. but -12V wont be able supply much current because it uses capacitors(less efficient and poor current delivering capability) if you want negative voltage the you have use boost convertor circuit.

 

[paulopca]

I appreciate the responses.
I took this circuit a mixer. See the link below.
Attached is the wiring diagram I found on the Internet.
I was looking on the internet a source circuit that works with 120Vac or 12Vdc and provide output +12 Vdc and-12Vdc, then I found this circuit.
I mounted the power supply but the oscillator does not work, so I switched by transistors BC546 and it worked.
The negative voltage of -12Vdc only attains -4VDC.

http://www.oneal.com.br/#produtos?id=171

 

[ZekeR]

Paolo,

If you are drawing a large amount of current from the negative supply, then I would highly recommend changing your transformer to something with a center tapped output winding. The reason the designers of that mixer could develop -12V using that circuit is because their circuits aren't drawing very much power from the negative rail. Using a charge pump circuit to develop -12V with high current would place tough demands on the capacitors, not to mention, creating imbalanced positive/negative rails.

If you absolutely, positively cannot use a transformer, you may consider reducing the values of R2/R4/C1/C2 to increase the charge pump's switching frequency (try to push it to ~400kHz or so). You can also put multiple charge pump circuits in parallel.

For the ultimate in voltage regulation, you can use a boost converter configured with two inductors to create an inverted output as in a `Cuk converter--see here, page 32 (bottom circuit).