Re: frequency response

"ranger" <linuxfreak87@xxxxxxxxx> schrieb im Newsbeitrag
news:1179195349.937021.53950@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I'm trying to plot the frequency of a power supply I've designed. Here
is the net list:

PowerSupply

v1 4 5 dc 0 sin(0 34 60)

D1 4 2 1N4007
D2 0 5 1N4007
D3 5 2 1N4007
D4 0 4 1N4007

c1 2 0 1000u
c2 2 0 100n
cout out 0 100n

radj adj 0 5k
r1 out adj 240

x 2 adj out LM317

.include parts.lib
.control
set units=degree
destroy all

tran 0.01ms 100ms
plot v(4,5) v(out) vs (time*1000)

destroy all

ac dec 10 60Hz 7000Hz
plot ac1.v(out) vs ac1.frequency

.endc
.end
--------------------------------------------------------------

I'm not doing it correctly though.

Hello,

I tried a transient analysis of your netlist with LTspice and it worked in
principle
but there is a small oscillation at the output. The value of Cout is
undersized.
Just increase its value to 10u and you will be saved.

For the second plot (freq
response), I get values in excess of 6000V ! This is so wrong as my
calculations have shown just above 28V is possible.
Please assist me in doing a frequency response.

How can you run any .AC-analysis without any source having AC specified?
It's impossible. Please explain where your AC is specified.

AC-analysis is a linear system analysis in SPICE!
It has nothing to do with the AC-voltage applied to your rectifier diodes.
Where do you want to apply the AC-voltage or current?

Best regards,
Helmut

PS: Nobody can exactly reproduce your circuit wihout knowing your LM317
model.


.