# Peak Secondary Voltage

Discussion in 'Homework Help' started by wtfman, Oct 8, 2011.

1. ### wtfman Thread Starter New Member

Oct 7, 2011
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For a full wave rectifier.

I know the formulas for the peak load voltage but i need the peak secondary voltage to start

And for the Half wave rectifier.

See second attachment.

I used the silicon as the diodes for both the problems

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Apr 26, 2005
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3. ### wtfman Thread Starter New Member

Oct 7, 2011
12
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For the Full wave rectifier,

Vsec = Vin (1/4)
Vsec = 20 V

For the Half wave

Vsec = Vin (1/2)
Vsec = 57.5 V

That is my attempt at the solution? Any good?

4. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,373
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Vsec across the secondary ... is correct ... however, the drawing represents a center tapped secondary coil and that must be considered and the voltage drop across the diode must be considered when your computing the Vpeak across the load.

Your attempt is the Half-wave needs work. Re-read the question and post another attempt.

5. ### wtfman Thread Starter New Member

Oct 7, 2011
12
0
Wait is my Vsec for both correct or wrong....Cause i need them and i know what to plug in for load voltage

6. ### wtfman Thread Starter New Member

Oct 7, 2011
12
0
Ok my attempt again for the secondary peak voltage:

Half wave:

Vsec = 115 VAC * 1.414
= 162.6 V

Is that better?

7. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,373
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The voltage across the secondary is 20V peak however, since it is a center tapped transformer, only half the voltage is between the center tap and the outer connections.

That's better for the input voltage expressed as peak voltage. It is incorrect as the secondary voltage. Now you need to finish the question.

Provide your full work for each problem.

• ###### Transformers_4_to_1_Ratio.png
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Last edited: Oct 9, 2011
8. ### wtfman Thread Starter New Member

Oct 7, 2011
12
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So the Vsec for the full wave would be 10 V. What about the Vsec of the half wave. What do I do with the peak voltage i calculated?

would it be:

Vsec = Vin (1/2) * 1.414
Vsec = 57.5 V * 1.414
Vsec = 81.3 V?

9. ### JoeJester AAC Fanatic!

Apr 26, 2005
3,373
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The Vsec on the first one is 20V however, as the circuit connected to it splits it into half ... as it is wired.

What is the real question to this problem? The voltage on the Secondary or the voltage on the load?

If it's the voltage on the secondary ... it would be 20 V ... but 10 volts between the center tap and outer connections. You don't have to worry about the center tap until you wire the circuit as drawn. If it's the voltage on the load resistor, you have more work to do.

For instance, on the first circuit, if your meter is connected to ground and you measure the secondary (top or bottom) ... it will read 7.07 V rms. If you measure across the secondary, (top and bottom), you will read 14.14 V rms.

On the second problem, yes there is 81.3 Volt peak on the secondary.

10. ### Aerosky New Member

Oct 13, 2016
1
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It's funny how I came across these exact same problems after 5 years! But this helped me a lot.