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Download LTSpice/SwitcherCAD III from the Linear
Technology website. |
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Download the generic triode model (click
link on the left), you want the PSPICE one as LTSpice understands them
just fine.
Save it to the folder where you will be
putting your schematics. |
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If you want to use the heater model, a
symbol will need to be made up for it - this is easy with LTSpice.
File|Open, change the drop-down box to
Symbols (*.asy) and navigate to the folder lib\sym\Misc. Open up
triode.asy |
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Use File|Save As to change the filename to
triodeh.asy ("h" as been added to signify heater). Press p
to place the first heater pin, call it H1 and then press p again to add
the second heater pin called H2. Save it. |
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You should now have exercised your
artistic skills to come up with something looking like the picture on the
left.
To save time, you can download a ready
made triodeh.asy if you wish
saving it to the LTSpice folder lib\sym\Misc so the software can find it.
If the file comes back as a load of text, best to use right-click and Save
As on the link.
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Draw up your schematic, the help file is
pretty good and got me up and running and about 5 minutes.
Note that AC heater is used and should be
8.91V not 6.3V as sine waves on SPICE are measured at peaks. 8.91 =
6.3 x sqrt(2). |
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From the menu, Simulate|Edit Simulation
Cmd, and make sure that Start external DC supply voltages at 0V and
also Skip initial operating point solution are checked. Also
pick a time for the simulation, in this case 15 seconds.
This is critical and
applies to any simulator, not just LTSpice. If you leave them open the
simulation engine will try and iterate to a solution before the heaters
have warmed up. |
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Press S to invoke a new SPICE directive,
and type .inc dmtriode.inc or whatever name your triode models are
in. |
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Simulation|Run completes the
picture. Click on the pic on the left and see how the plate voltage
sits at 250V then comes down as the tube warms up.
You can download this schematic by clicking
here. If a load of text comes up, use right-click and Save As. Make sure that dmtriodep.inc is in the same folder.
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On the left, another simple schematic
which feeds 200Hz to the tube and you can see the output "come
alive" as the tube warms up.
You can download this schematic by clicking
here. Again, be sure that dmtriodep.inc is in the same
folder. Start it running and make a nice hot cup of tea - even on my
1200MHz machine it takes a little while...
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Here's another to try out, a small
EL84/6BQ5 amp with a pair of ECC83/12AX7 stages and negative feedback.
Download the zip
file and extract the files to where you normally store your LTSpice
schematics. |
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Another example with a pair of EL34/6CA7
being driven by the ECC81/12AT7 as a preamp and phase splitter in guitar
amp style.
Click
here to download the zip file. |
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Any queries, comments, suggestions,
complaints, please stick 'em on the
forum! |
