# Full-bridge rectifier not working as expected

Im trying to create a full bridge rectifier from a step-down voltage source. The circuit is as follows:

simulate this circuit – Schematic created using CircuitLab

The problem is that I'm only seeing a half-bridge behavior across the capacitor. I am doing this in HSpice, the code can be found below. The end goal is to create a +12 and -12 voltage source, but for now, I'm just trying to get the full bridge rectifier working. Anyone know where I'm going wrong?

P.S. - not including the GND in the secondary side causes a convergence error.

Vsource 1 0 SIN(0 339.41 60)

C1 3 4 6m

Etran 2 0 TRANSFORMER 1 0 10
D1 4 2 dp1
D2 3 4 dp1
D3 4 0 dp1
D4 0 3 dp1

.MODEL dp1 D LEVEL=1

.OP
.TRAN .00066 .033
.PRINT V(1)
.PRINT V(2)
.PRINT par('V(3)-V(4)')
.PRINT V(3)

.END

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I do believe there is not a rectifying action here because the diodes don't "pump" up the cap ... –  Spoon Apr 17 '14 at 19:18

D2 is connected across the capacitor (node 3 to node 4) instead of from the transformer to the capacitor

D2 3 4 dp1

Should be

D2 2 3 dp1

If I remember correctly. Brings back bad memories, this does.

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To get a sensible voltage measurement across the capacitor in the circuit you have shown, you need to ground one side of the capacitor, not one side of the transformer secondary.

To get a bipolar supply (+/- 12 volts), you need a grounded center tap on the transformer secondary.

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I don't much about Spice, but how are your voltage measurements referenced? You'll have some problems if they are referenced to the ground you placed. It would be more useful (and it's customary) to put the ground at the negative side of the capacitor.

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I am referencing across the capacitor –  scordova88 Apr 17 '14 at 3:05
If you want the DC voltage of the secondary to be measured as expected as @gbarry says attach the ground to the capacitor. This looks like D4 and D1 are redundent .... On the positive half of the cycle D2 conducts, on the negative half D3 conducts ... In summary because you've tied the ground to the wrong place it's not working ... either that or I really needs some sleep.... –  Spoon Apr 17 '14 at 12:30