Is possible to obtain a resistor controlled by RMS of a voltage in LTSpice? The syntax \$R=V(n001)\$ works, whereas \$R=rms(V(n001))\$ does not work.
Thank you for your time.
Electronic – LTSpice – resistor controlled by RMS
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Related Solutions
From what I understand, the .PARAM directive is evaluated at startup. The answer to your literal question is thus no.
You can, however, put the equation as the resistance:
If you read in the LTspice manual, you'll see that it says it's breakdown voltage is set by the voltage applied at its control terminals. The voltage can be of any sign, any polarity (it counts as abs(V(ctl))), and the calculation is like this: if your applied voltage is 10V, the series resistance is 1 Ohm, Rclamp=1 and the control voltage is 1V (I presume), then the varistor will breakdown at 1V (the controlling voltage), meaning from the total of 10V you'll have 10-1=9V which, divided by the total resistance of 3 Ohms results in 3A. If your source voltage is 7V, series resistance is 2 Ohms, Rclamp=1.5 and controlling voltage 3V => (7-3)/(2.5+1.5)=4/4=1A.
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Best Answer
RMS is a computed value related to the "output" and therefore it cannot be used to change the value of a component (an input value) because you get a circular problem. Maybe you can take Vn001, and feed it through an RMS to DC converter. Maybe use a multiplier to get v\$^2\$ then low pass filter it then, use a square root circuit: -
Most sims have the multiplier "part" and, with an ideal op-amp (not a TL081 as shown above) you can extract the square root and hence the RMS.