Transient Analysis But 0V DC .OP LTSpice

[GBeared]

Hi. First, thank you for reading my post.

I am learning how to use LTspice. Here is a simple bridge rectifier/smoothing circuit below, along with the .asc file. Transient analysis is roughly matching what my calculator spat out, but I am getting 0V DC opperating point on every node

. I assume I have made a simple mistake or have a missing Spice directive?

Any help, adivce would be greatly appreciated.




View attachment Filtered DC.asc

 

[bill_a]

There's no DC source in the circuit, so you won't get any DC values with the .OP directive.
Bill

 

[GBeared]

Ah, I think i see... so the spice sim will not simulate rectification? I need to add a parallel DC source ?

 

[bill_a]

Spice doesn't know its a rectifier - how can it? A rectifier is not a DC source - it only approximates a DC source eventually. The .op function examines the circuit at t=0, and the output of a rectifier at that moment is zero.

You have it right there in your schematic - the .trans function should show you all you need to know. Run it long enough and the output will stabilize at some ripply average value, but its still not DC.

 

[jkuetemann]

The 'startup' option prevents spice from even doing a DC solution prior to the transient analysis, so when you probe a node there is no steady state DC value to give you.

 

[Elvee]

Ah, I think i see... so the spice sim will not simulate rectification? I need to add a parallel DC source ?

Note that if you want to stay within the .op domain (why?.?), you can add a phase shift to your sine input source: with 90° you will be close to the actual working voltage