Rectifier and Smoothing - help with power supply

[GooseElectro]

I am trying to make a + / - 5v Dual rail power supply for an audio IC (PGA 2311 - **broken link removed**)

I am using a 240vac 50hz 0.26A transformer (meant to be used for LV Halogen Lamps), with a 11.6v ac (eff)? Max 4.9A output.

I need to know exactly what sort of bridge rectifier to use and a smoothing capacitor to match that will allow me to attach this voltage inverter (ICL7660SCPA CMOS Voltage Convertor Components Maplin)
and two +5v voltage regulators. (I am not sure if i need a -5v regulator after the inverter?)

I also want the rectifier and smoothing capacitor to allow me to use the transformer for other dc circuits and want to be able to use the transformer at it full power. ie full 4.9 A

Could anyone tell me which one out of this list will be suitable for the rectifier - Bridge Rectifiers Components Maplin

Thank you for any suggestions

 

[MikeMl]

Does the transformer secondary have a Center tap? How symmetrical is the load on the +5V and -5V outputs?

 

[bychon]

Did you know you can make both +5 and - 5 with one transformer?

 

[GooseElectro]

Here is a picture of the transformer I want to use:

**broken link removed**

 

[MikeMl]

No center tap, so you only have two choices: Use a full-wave bridge rectifier to make a single 10V regulated supply which is split into +5V and a -5V using an active electronic center tap, or use only half-wave rectification to create unregulated +V and -V followed by one each positive and negative regulators to create the +5V and -5V.

The second method requires much larger filter capacitors (2 of them) than the first method. If you had two transformers, one transformer with two secondaries, or a higher voltage secondary with a center-tap, it would be much simpler and more efficient (less ripple, less dissipation in the regulators) than trying to do it with just one non-center tapped winding.

 

[ronv]

Power supply

What a neat part.
From what I see on the net the output of your transformer will be between 20 and 40 KHZ. Might want to scope it if you can or if you have specs. But we can assume the low end at 20 KHZ. I think I would build the bridge out of 4 descrete shottky Diodes. I think you can get 6 amp ones easily enough. A filter of 470 Ufd at 16 volts should keep the ripple below 1/2 volt with an output of around 13.75 volts peak. From the looks of the voltage converter if you use a +5 volt regulator from your bridge to feed it you will get -5 out. No extra regulator required on the output of the converter.

 

[GooseElectro]

No center tap, so you only have two choices: Use a full-wave bridge rectifier to make a single 10V regulated supply which is split into +5V and a -5V using an active electronic center tap, or use only half-wave rectification to create unregulated +V and -V followed by one each positive and negative regulators to create the +5V and -5V.

The second method requires much larger filter capacitors (2 of them) than the first method. If you had two transformers, one transformer with two secondaries, or a higher voltage secondary with a center-tap, it would be much simpler and more efficient (less ripple, less dissipation in the regulators) than trying to do it with just one non-center tapped winding.

Thank you very much for your reply.

I would like to know a bit more about both methods that use the transformer i have shown.

I want to make both a +5v,-5v supply and a +V supply to use with this transformer

Could you give more detail about the components and their values. (full-wave bridge rectifier , half wave rectifier )? (I already have the regulators)

thanks again

 

[MrAl]

Hello,


To the OP: what kind of ripple are you looking for?

 

[GooseElectro]

Hello,


To the OP: what kind of ripple are you looking for?

I am not realy sure would this depent on what regulators i am using, i understand that the regulators would eliminate the ripple.

 

[mneary]

Different regulators are able to tolerate more ripple before they fall out of regulation. If a filter is suggested that leaves too much ripple for the regulator you're using, then its performance will be poor. If you choose a 'better' regulator and the filter is overdesigned, you money is wasted.

 

[ronv]

power supplies

Here is a little diagram. The diodes are the 15 amp ones shown on maplin (N13CC). They will still need a bit of a heatsink if you are going to use the full 4 amps. Probably a good idea to put in a fuse and follow the datasheets for the regulators.