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LTSpice triode model

I found these triode models:

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The LTSpice .asc file below shows anode current when Vgc < -80V. Do valves do this, or is it a bug in the model? What's the fix?

Version 4 SHEET 1 2020 680 WIRE 928 176 832 176 WIRE 928 192 928 176 WIRE 832 288 832 176 WIRE 928 288 928 272 WIRE 928 336 880 336 WIRE 928 368 928 336 WIRE 864 464 864 384 WIRE 928 464 928 448 FLAG 928 288 0 FLAG 928 464 0 FLAG 864 464 0 SYMBOL voltage 928 176 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName Va SYMATTR Value 150 SYMBOL Misc\\\\triode 832 336 M0 SYMATTR InstName U1 SYMATTR Value NH12AU7 SYMATTR SpiceModel NH12AU7 SYMBOL voltage 928 352 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName Vgc SYMATTR Value "" TEXT 1040 288 Left 0 !.include dmtriodep.inc TEXT 1040 368 Left 0 !.dc Vgc -150 0

Reply to
Andrew Holme
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Basically there are two kinds of triode models, the Leach and the Koren. I favor the Koren models. I have found them to be reasonably accurate if you stay within normal operating parameters. Get too far away from that and the models get quirky.

Best regards,

Fred

Reply to
Fred

I don't know (or care ;-) ) much about SPICE, but I know plenty about 12AU7. If plate voltage is over 1kV or so, I might expect to see some current at -80Vg. At any plate voltage, there will be some leakage, which should be much less than a miliampere, especially at -80Vg.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
Reply to
Tim Williams

The above model is very wrong at Vg < -80V.

I've just found a better one on the same website:

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Reply to
Andrew Holme

Better in one way, worse in another :(

This manages to suck 22.8mA through a 68K anode load resistor from a 150V supply, giving an anode voltage of -1.4KV.

Reply to
Andrew Holme

I'm now trying the Norman Koren models, which seem to take anode voltage into account and do sensible things at both extremes of grid voltage.

Reply to
Andrew Holme
[snip]

Thanks, Andrew! A whole set of very good links!

Now I'll have to re-visit my youth and design some tube amplifiers ;-)

...Jim Thompson

-- | James E.Thompson, P.E. | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice:(480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at

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| 1962 | I love to cook with wine Sometimes I even put it in the food

Reply to
Jim Thompson

I have seen power tubes with substantial anode current at -80 V Vgc, however this is not appropriate for a small signal triode like a

12au7.
Reply to
JosephKK

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