Transformer for dual rail power supply - Help

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GooseElectro

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>> I am trying to make a +/- 5v dual rail power supply for this digital volume control IC: PGA2311 - Datasheet, and other devices such as a 741 op-amp. <<

I belive i will only need about 50mA for these devices ?

I would like to use these regulators to regulate the output of my power supply:
L7805 Positive Regulator - Data sheet
and KIA7905PI Negative Regulator - Datasheet

I have found this transformer: **broken link removed**, will this be ok for what i need ?

What sort of rectifier will i need ? and What sort of smoothing capacitors will i need ?

How should i fuse the power supply ? Should i fuse it before and after the transformer ? What value fuse should i use 1A ? or smaller ?

>Any suggestions are much appreciated<
 
MikeMl said:
Did you look at the link?
Click to expand...

Yes I have and it was very useful but I would still want to know if the transformer that I have found is ok ? and how would I fuse the circuit ? I am using uk voltages and I asume that the regulators I suggested would be fine ?

Thank you for your help ?
 
Yes, the transformer has a 9-0-9 output so if you don't need more than +/- 50 mA it should do fine. Also if you use a 7805 I would use a 7905 for the neg regulator.

Ron
 
Here is the basis of your split supply. Should be good for ~50mA with the transformer you linked. Fuse the transformer primary with a 1/4A glass fuse in an appropriate holder.
 

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Reloadron said:
Yes, the transformer has a 9-0-9 output so if you don't need more than +/- 50 mA it should do fine. Also if you use a 7805 I would use a 7905 for the neg regulator.

Ron
Click to expand...

Thank you very much for you reply it was very helpfull, in the mean time i have been shown this circuit which uses a transformer that i already have, i would idealy want to use this one:

**broken link removed**

I already have this thransformer that i think will be the same as the one in the circuit ( just can supply more current?):

**broken link removed**

could you tell me if i already have the right transformer and are these component ok for the circuit? :

**broken link removed** 1N4002S ?
**broken link removed** 4700uF 35v??
**broken link removed** 10K ?
**broken link removed** L7905CV ?
to go with
http://www.datasheetcatalog.org/datasheets/270/9554_DS.pdf

thanks again
 
MikeMl said:
Here is the basis of your split supply. Should be good for ~50mA with the transformer you linked. Fuse the transformer primary with a 1/4A glass fuse in an appropriate holder.
Click to expand...

Yes i see, would i need a fuse the secondary side of the transformer? and could i put this fuse in the mains plug? Would it be the same fusing if i were to use the other (white) transformer?

Thanks alot for your help.
 
I would not use the "electronic transformer". It is a switcher, god knows what frequency it switches at; it likely radiates switching crap into your analog signals; god knows if it is even isolated from the 240V input line. Use the iron transformer. Fuse only the 240V side.
 

Right i see, so i should use this transformer :
**broken link removed**
and this circuit:
**broken link removed**
?

Could you tell me if the components i have suggested in a previous post will be ok and will this fuse be ok?: **broken link removed**
?

thanks again
 
The 18Vct transformer will provide enough voltage for the 7805/7805 style regulators.
The glass fuse is fine, but you need a holder for it, like the Buss HKP.

I would use a 1/4A slow-blow (time delay) fuse. Maybe you want to add a line-rated On/Off switch, too. Someone may have a better idea on the fuse rating. I deal with 120V AC, and haven't dealt much with 240V.
 

Ok thanks alot.
which one out out these fuses woulds be correct, they are in A not W: **broken link removed**

Could you tell me if the components i have suggested in a previous post will be ok and will this fuse be ok?:

thanks
 
I correct my self about the volts and the WATS for the fuse.

I think the components i have mentioned in post #8 will be ok ( not the transformer i will use the 9-0-9 transformer), could somebody clarify this ?

Thinks allot for your help.
 
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