# Does this two circuit have the same output?

Discussion in 'General Electronics Chat' started by simpsonss, May 26, 2010.

1. ### simpsonss Thread Starter Active Member

Jul 8, 2008
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hi,

I'm confuse about using this two type of transformer to get the same output voltage.
Does the two circuit below have the same output voltage?

thank you.

2. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
The lower circuit is not drawn correctly.

The ground output needs to come from the left side of the bridge, like the top - not the bottom.

If the correction were made, then yes - the output voltage under no load would be the same.

3. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
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or issit should be in this way to get the same positive voltage?

thank you.

4. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
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Actually i want to combine this two circuit by using only one center tap transformer. At first i'm using two type of transformer but now i want to combine it to become using one type of transformer. Any idea?

thank you.

5. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
That will work.

6. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
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u mean which circuit?in which say i should combine the two circuits together?

7. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
I meant that the circuit you posted (the right side of the image) in my last reply will work.

You need to give some more specifics, such as the transformer rating. If it is not rated for sufficient current or wattage, your output will not be what you might expect.

8. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
0
sorry just to make things clearer, i make a summary for the circuits.

So the above and below have the same output voltage right? For the Amp i need for my circuit will be enough because my transformer is a 1A rating, and my circuits will just need less than 1A. The more thing i concern about is whether i could combine the two circuits become just using one 24-0-24 transformer to save down one transformer.

Does the circuit at the bottom part of that paper work in the same way as the above part?

9. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
No. It will not work like that.

10. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
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so is it possible to use only one 24-0-24 center tap transformer to have the output voltage that i wanted?

thank you.

11. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
What voltage do you want output?

You have not yet mentioned that. Shall I simply make guesses?

12. ### simpsonss Thread Starter Active Member

Jul 8, 2008
173
0
ok. my circuits need 3 voltage output.
1. I need a Vpeak of ~30V, so i decided to use a 24-0 transformer.
2. then, i need positive 12V and negative 12 voltage for my circuit too.

Any idea?

thank you.

13. ### SgtWookie Expert

Jul 17, 2007
22,201
1,807
I don't know what your current requirements are. With a 24v input transformer, your 30v output will have a good bit of ripple on it.

Anyway, here's what you need to do:

The outputs will not be regulated. You will need to add regulators to achieve a relatively stable voltage output. It will not be possible to suggest capacitor values unless you suggest what the maximum load current will be.

You must use a fuse on the input. It can be a slow-blow fuse, but a fuse must be present. This will protect everything past the fuse from overload. If you do not use a fuse, your project may quickly go up in smoke. The fuse must be in the line voltage side of the circuit.

The power switch S1 is optional. If you choose to include one, it must be after the fuse.

If you really want to go with just ONE transformer, it is possible to generate multiple voltage outputs using switching regulators; however that is a somewhat advanced topic.

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Last edited: May 30, 2010

Jul 8, 2008
173
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