LTSpice Noise Voltage Source

A behavioral voltage source can be used in LTSpice to create arbitrary voltage waveforms, including noise with the white(x) function.
Here's how to implement that noise source and combine it with a sine wave signal.
LTSpice files used: github.com/GadgetReboot/misc_...
Behavioral Sources ltwiki.org/?title=B_sources_%...
General Noise Source Simulation Info: www.allaboutcircuits.com/tech...
PWL Voltage Sources www.ieee.li/pdf/viewgraphs/lt...
V/I White/Flicker Noise Source subckt github.com/yildi1337/LTspiceN...
LTSpice Tips www.circuitszoo.altervista.org...
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[@CARlosDAN783]

Hello friend, I am investigating the ripple noise from the output of car alternators, especially 12 and 24 volt alternators, I have seen some videos of what the outputs of these alternators are like and I wanted to see if I can simulate them. with LtSpice, and with your video I have come to the conclusion that I can. Your video has been very helpful to me, that's why you earned my subscription and hands up. Greetings from my beautiful Venezuela.

[@TheEmbeddedHobbyist]

Nice to use if your designing input filters on switching inputs, at least you can simulate your circuit to see if you have hit the sweet spot. I still like to breadboard circuits as spice does not capture ones own x-coupled problems caused by the layout. 🙂

[@gadgetsideload]

simulating and real-world testing have worked together for me where I didn’t understand why a breadboarded op amp circuit wasn’t producing any output about 25 years ago. It turns out the op amp didn’t like very much capacitive load so the capacitor in the Feedback Loop was loading down the output even though the simulation with an ideal op amp was working. So then I found a spice model of the exact op amp on the TI website and saw the simulation was acting the same as the breadboard and somehow I stumbled on the capacitor load issue. I switched op amps and the breadboard worked fine. back then I had to use just text editing ASCII spice files so at least it’s easier now.

[@TheEmbeddedHobbyist]

@@gadgetsideload bring back the ASCII spice where you had to work out all the nodes for yourself. i can remember running it on a 8086 with twin floppies in a home made case. back then electronics was fun, no massive black chip that did it all. logic was a board full of gates and maybe a PIA if you could afford one. happy days.

[@mohameddrissi1075]

hello friend , thanks for the quality video . I'm trying to simulate an electret mic + its noise and i wanna add this noise to the simulation by injecting the noise spectral density into a noise generator ! is there a way to do that ?

[@fixinggood4595]

With the 10k and 2k resistor at the opamp, the gain should be 6. With an input signal of 1V the output should be around 6V. Why is it only ~3V? Is the behavioural voltage source connected wrong?

[@gadgetsideload]

It has to do with the 10K summing resistors in line with the noise and sine wave signals. If you change the 10K to a 10Meg in line with the noise you'll see a 6v sine wave because the noise is effectively out of circuit but if you look at how the output voltage is derived based on 2 input signals with series resistors, you'll see that two resistors of the same value at the inputs will reduce the output by half masteringelectronicsdesign.com/how-to-derive-the-summing-amplifier-transfer-function/