having problem creating a noise source in multisim

[niloy2k]

Hi i am working on a project which is known as the lock in amplification of weak signals buried in noise .... i am asked to simulate the entire design in multisim first and then design the circuit ... the problem is i cant seem to find a way of generating a noise source.... is there anyway of doin so ?? can anyone help me out plz ?? will really appreciate it .... thanks

[yyao]

Hi there,

If you want to generate noise for a transient simulation, you should use a signal source. Take a look at the THERMAL_NOISE component in the SIGNAL_VOLTAGE_SOURCES family of the Sources group. This component generates random samples for every simulation. Alternatively, you can also use a TDM_* or LVM_* source which outputs a signal from a file, but the signal may not be as random as you like.

[niloy2k]

I am not entirely sure about how to use the transient analysis but the way u askd me to do it, can i see the output in da oscilloscope as random signals rather than lets say a sine wave ? Is there anyway to create a noise source in a practical breadboard experiment using basic electrical components ? And also this question might be out of the topic but is there anyway of interfacing circuits between multisim and labview ? Thanks 🙂

[yyao]

A transient analysis is one that simulates a circuit over time. Using the oscilloscope in interactive simulation (when you click the simulate button) is an example of transient simulation. The thermal noise source will work with an oscilloscope in interactive simulation.

As for creating a real life noise source, I've seen ones made with zener diodes, but I haven't built one and can't help you there. If anyone who can share some insight on building and simulating one, that would be greatly appreciated.

Multisim does have capabilities of interfacing with LabView! This is a pretty advanced topic, there's an entire section on it in the Multisim help file. There are also examples and templates in the samples folder for your reference and to start you off.