I don't understand why I'm getting this Thevenin resistance in my LTSpice circuit

[ntetlow]

Attached is an ltcpice net file.
The thevenin resistance betweed the 3ohm and 6ohm resistor is 7.6 ohms. This works out as 3ohms plus the parallel value of 20||6 (4.6ohms).
My problem is - Why is this the thevenin resistance, could someone please explain?

 

[berkeman]

Attached is an ltcpice net file.
The thevenin resistance betweed the 3ohm and 6ohm resistor is 7.6 ohms. This works out as 3ohms plus the parallel value of 20||6 (4.6ohms).
My problem is - Why is this the thevenin resistance, could someone please explain?

My LTSpice software is on a different computer from the one I'm working on right now. Can you post a couple of screenshots of your circuit and your simulation results?

 

[ntetlow]

Thanks for the reply. Screenshot attached.

Neil

 

[ntetlow]

Sorry, just realised that i've sent a different version of the ltspice, instead of 20ohms as above, please read 9 ohms(2 +3+4) making the thevenin resistance 6.6ohms

 

[berkeman]

What voltage is ##V_1##?

 

[ntetlow]

V1 is 1 volt. it is used to measure the thevenin resistance. the screenshot shows the current
The current is 151.51mA, dividing 1 by 151.51mA gives a resistance of 6.6 ohms.

 

[berkeman]

Sorry, just realised that i've sent a different version of the ltspice, instead of 20ohms as above, please read 9 ohms(2 +3+4) making the thevenin resistance 6.6ohms

That looks correct (I've deleted a couple replies of mine just now that were wrong). The 3 Ohm resistor in the ##V_1## source leg is in series with the 9//6 Ohm resistances.

 

[Baluncore]

Attach the LTspice.asc file to a post by renaming it as LTspice.asc.txt
Rename it to LTspice.asc then run it as LTspice program. See attached.
If you post a netlist, we must paste it as a command, then we see a different layout to you.

 

[ntetlow]

Yes, I see it now, just a matter of shifting things round, I wondered if that would do it.
Thanks for your help.

Neil