Reset timestep.It is to small & I can't work out how to increase it.

[jpr905]

Hello team,

I am using Multisim version 9.0.17 and I am encountering a timestep issue.

Originally simulations were all run with the default timestep but I have changed the maximum timestep (TMAX) in the "interactive simulation settings" to be very small for a simulation with an AM radio. 

The problem I have now is that I want to increase the timestep (TMAX) so that the simulation runs faster for this AM radio. After I have increased the timestep(TMAX) the simulation still runs with the old small timestep (TMAX) even after restarting my computer.

I have changed the "initial time step" in the "interactive simulation settings" but this did not help.

How can I get the simulation to run again with a larger timestep?

Kind Regards

John Roberts

God bless

Ps attached is the circuit incase it helps.

[lacy]

I do not believe you are going to get it to simulate much faster than what it is simulating. This is due to the high carrier frequency of 900Khz. The higher the frequency of the signals, in most cases, the slower the simulation will run. This also depends on the compexity of the circuit as well.

I have changed everything I can think of and even on Version 10.1 it crawls very slowly.

 Instead of using the simulator run switch, you might want to consider the other anaylsis options under SIMULATE>ANALYSIS. I just ran a Transient Analysis from the menu items and it displays the results on a graph simular to the O-scope and did it almost instantly. This is just a thought if you want a faster output results.

The normal Tmax settings are anywhere from 1e-003 to 1e-005. You can plug these into the TMax setting to get it back to normal or just select Generate Timesteps Automatically just under the TMAX setting.

I hope some of this helps. I could possibly be overlooking something, but right now this is all can can see to help.

[jpr905]

Hello,

Thanks for getting back to me so soon. After recieving your post I did some more tinkering. I copied and pasted the circuit onto a blank page and then ran the simulation. This time the simulation ran at a resonable speed. This must have reset some timing paramaters somewhere. Thanks again.

Kind Regards

John Roberts

God bless

[lacy]

I have been doing some more investigating on this an I have found something intetresting. I removed the Spectrum Analyzer from the circuit and it definitely simulated faster. I  wanted to take this further and found a sample circuit in the help file and hooked it up to the spectrum analyzer and sure enough even with this very simplistic circuit the simulation speed droppped to being extremely slow.

So it could possibly be the Spectrum Analyzer bogging down the simulator. I am examining this in Version 10.1, so i can not say for sure that this is your problem, but there isn't much difference between the two as far as functionality is concerned.

I thought I would pass this along in case this helps get the speed up for you.