Why does Multisim keep my LEDs alive?

[komolono]

I have a circuit that keeps burning my LEDs. I sort of know the answer why, but is this normal Multisim behaviour?

[Finland_]

Hello!

Some NI hardwares turn on and stay as "ON" position if you don't switch it off. Closing a programme or exiting an application doesn't switch LEDs back to "OFF"-position. You can switch the LED on. How about switch it off? Can you do it?

BR,

Make Nguyen

NI Finland Technical Support!

[komolono]

This was not my problem - if I don't add serial resistors to every LED line, the LEDs will be damaged (in real world).

[Finland_]

Hello!

I am not quite following with you at the moment. Could you please specify your problems with more details. Adding pictures of your setups and codes might help me a lot.

BR,

Make Nguyen

National Instruments Finland Technical Support

[Finland_]

Hi!

I am getting multisim, I just have the older version (11.0) so I couldn't open your ms12 file. Do you have ultiboard attached so you could evaluate your multisim simulation as well?

Br,

Make

[Tien_P]

Hi,

Most parts in Multisim are ideal and the components rating are not part of the simulation. In Multisim, applying too much power to a component will not cause a simulation error but in real life, it will destroy the component.

[Finland_]

Hello!

Sorry for not noticing your ms12 file before. I got your file open. I can see from your file that the LEDs are taking ~45 mA but the circuit are seeing them as 1.3 GOhm. Isn't this a sign of when LEDs are overloading? I mean, LEDs cannot consume that much of resistant right? Multisim just simulate the situation you got, you can input mega volts to the circuit and it is still functioning. I think Tien P. is right, the components are ideals and they will "never" break down.

BR

Make Nguyen

[komolono]

OK - thanks all! Nowadays I add a parallel capacitor at the output and measure current/voltage and add a serial resistor before LEDs.

[Finland_]

I am glad that you got the solution. I will close this case for now. Is there anything else that we could help you out?

BR,

Make