05-05-2018 08:25 PM
Hi. I'm pretty new to this software, so I am not sure if I am making a mistake with my circuit setup, but all of the components I am attempting to use are in their default setups. I have made a basic npn transistor current source using a 2n3904 to drive a LED with a 220 ohm at the emitter. With 5V at the base and a 10V collector supply I should easily have about 20mA through the LED, but I am only measuring a few pA. I have done a previous lab experiment where I was also having issues with this transistor in a base biased setup, so I suspect that there may be a setting that I need to change??? I attached the image of my circuit and the transistor model information to see if anyone can help me figure out what might be wrong.
Thanks for any help! I'm in an online class and the communication with the professors has been very spotty and not at all helpful.
Dan
05-06-2018 11:48 AM
Hi,
The attached design file simulates to 19.2 mA in Multisim 14. This was drawn from database parts. If you are modifying transistor parameters or the insertion resistance of the ammeter, your results will vary.
If you can export your transistor parameters to a text file (haven't tried it) and also export the database parameters, you can use a comparison engine to see what the differences are (I use Araxis Merge, you can probably use Notepad++ although you may have to install a plugin). In the digital world, there is nothing like a good file comparison utility!
All the best,
Jim S.
05-06-2018 01:14 PM
Thank you so much for your fast response! I looked at all of your setup and it is identical to mine, but I finally noticed that my resistor had a fault set on it I don't know how or when this happened, but everything is working properly with it now. Thanks again!