# Full wave bridge retifier transfer characteristic?

1. Sep 14, 2008

### deejay220989

Hi guys!

I've attached a picture below. That is a Full Wave Bridge Rectifier right?

I was just wondering whether is a Full Wave Bridge Rectifier's transfer characteristic the same as a normal diode's transfer characteristic?

If it isn't, then how does the transfer characteristic graph look like?

Thanks!

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2. Sep 14, 2008

### Redbelly98

Staff Emeritus
The attached figure is still pending approval, but I'll assume you mean a standard, common, 4-diode full wave rectifier.

If by "transfer characteristic" you mean a graph of Vout vs. Vin, then it resembles the absolute value function, modified slightly to account for the diodes' forward voltage drop.

However, it doesn't make much sense to talk about "Vout vs. Vin" for a single diode, so I don't understand how this comparison is to be made.

p.s. Welcome to Physics Forums!

3. Sep 14, 2008

### deejay220989

Sorry, I couldn't understand what you're trying to say coz my English isn't that good ><

Btw, I'll just tell you what I've done so far.
Using PSpice Student Ver. 9.1,

When I simulate this circuit using the DC Sweep Analysis (following the instructions on my assignment notes),

My result is:

This graph is the normal V-I characteristic (transfer characteristic) graph for a single diode right?

But when I analyze the Full-Wave Bridge Rectifier circuit using the same DC Sweep Analysis (this is a question of the assignment),

My results:
TRACE V1(RL)

TRACE V2(RL)

Both graphs combined!

I was wondering whether is this the graph I should be getting.
I hope you guys understand my question.

Thanks for helping ^^

4. Sep 14, 2008

### Redbelly98

Staff Emeritus
No. The diode's V-I characteristic would have current on one of the axes; that's the "I" part of "V-I".
Your graph has voltages for both axes, so it is not a V-I characteristic.

Note, your graph is the correct transfer characteristic for that circuit.

I understand the question better now.
Why do you have two plots for the transfer characteristic? It should just be a single graph, V_RL as a function of Vs.

Use V_RL = V2 - V1 and plot that as a function of Vs.

5. Sep 14, 2008

### deejay220989

I see..so V-I characteristic IS NOT transfer characteristic ><.
Thanks for clearing that up ^^.

Well, this is my first time using PSpice so how can use V_RL = V2 - V1 and plot that as a function of Vs?

I tried something but I'm not sure whether is this the right thing..

Btw, I need to clarify something about PSpice ><
1. Whats the difference between V1(RL) and V2(RL)? Does it mean the first half and second half of the sine waveform?

2. What is the meaning of V_Vs at the X-axis label? Why didn't they label the Y-axis? Does V-Vs mean "graph of V versus Vs"?

Thanks again

6. Sep 15, 2008

### Redbelly98

Staff Emeritus
That graph looks right. As I mentioned earlier, it is similar to an absolute-value graph.

I use LTSpice myself, so things work a little differently. But it looks like the resistor's two nodes are labelled #1 and #2. V1(RL) is the voltage at node #1 of the resistor, relative to ground. Similarly for V2(RL).

I think it means the voltage (V) across the component labelled "Vs". It may possible to graph things as a function of current through Vs instead, in which case the x-axis would probably be labelled "I_Vs" ... I think.

They will let you plot many different things, all on one graph, as a function of the x-axis variable. Like when you had V1(RL) and V2(RL). Then how would you label the y-axis? Instead, they provide a key, in the lower-left part of the graph, showing what the y-axis variable or variables are.

If you mean V_Vs, see previous answer. You could try changing the label "Vs" of the voltage source to something else, like Vsupply. Redraw the graph, and see if the x-axis label changes accordingly.

You're welcome.