Simple LED Circuit Simulation problem?

Hello, and I recently started to use Multisim so that I can design circuits using schematics and then trying them out on the protoboard. However something is confusing me from the simulation.
So on a real protoboard with 5V and a 330 ohm resistor and ground, I can connect a green LED and it will turn on. Obviously if I take out the resistor my led will burn out and it won't work anymore.
On Multisim, If I add a 5V VCC, a green LED and ground (no resistor), and when i start the simulator, it turns on. I'd expect the LED to be off since a direct voltage of 5V is not supported for an LED.
Is the simulator suppose to behave this way or how will I be able to tell if some circuits got burned?

I do not know how Multisim's LED is modeled. Many models do not include "burn out" factors. Since diodes have exponential current-voltage relationships, you may find that the LED is drawing several amperes at 5 V.
Most simulation models work well when the devices are operated within their normal ranges but may not be at all realistic when outside those ranges. For example some op amp models can produce output voltages far in excess of the power supply voltages, which real physical circuits cannot do. It is important to determine the limitations of the models when evaluating the quality of a simulation.
In many cases the only way to detect burnout is to calculate the power dissipated in the device and compare that to its rating.
Lynn

Similar Messages

Digital Simulation Problem, Xspice vs. VHDL

Hello EWB friends.
I am currently experiencing a problem with a mixed mode/digital simulation. The main problem is that the component that I am trying to simulate, a differential rs-485/422 interface transceiver, isn't commonly modeled using xspice syntax. Instead manufacturers and engineers that work with these interface components offer models written in VHDL (I suppose this is because creating this component in xspice is difficult/insufficient). This transceiver converts a differential analog rs-485/22 input signal to a TTL (0-5v digital) output and vice versa.
I am using Multisim V.10. The good news is that Multisim v. 10 supports mixed mode simulation using components modeled in VHDL. The bad news is that NI has discontinued Multi VHDL, which assembles the VHDL model into the .vx file format that is required for simulation with multisim. This is a problem for me; I understand that Multi VHDL v.8 works fine with Multisim v.10. Well that’s great and all, but NI does not sell Multi VHDL .8 anymore, it has been discontinued.
After weighing out my options I see two possible solutions to my problem. One is to obtain a copy of Multi VHDL v.8 some how, or have someone who owns the discontinued software to convert my VHDL model to .vx format for me. Two would be to design an Xspice sub circuit for this component (possibly a very slow and painful process).
I have noticed that some digital components are modeled using HDL and/or Xspice syntax; other components are only modeled using HDL (due to complexity). I have read and reviewed the Xspice user manual and examined its primitives. From what I understand the component that I am trying to simulate could be created as an xspice sub circuit, although most/all interface components are simulated with HDL. Does anyone know the limitations of xspice and what digital components are impractical to simulate using xspice? (Besides the obvious like MCU's and FPGA's) Or could anyone with Multi VHDL v.8 help me out and convert this file to .vx format?
This has been an on going simulation problem for me. I use analog interface to digital covertering drivers/receivers in the majority of my circuits and cannot simulate them using multisim. Any input, advice, or help would be greatly appreciated.
Here is the VHDL model that I am trying to assemble to a .vx file / trying to translate into xspice syntax. I converted it as a .txt so it could be posted, was originally a .vhd.
Thanks,
SPM
Attachments:
if490.txt ‏7 KB

I have Mutlisim 10 and under the simulation tab there is VHDL Simulation. Apparently in mine it is only a demo, but you can create VHDL components. I tried compiling your file, but it tells me that it is too large for the demo. It also says this " Better yet, purchase the fully function simulator by calling your local Electronics Workbench reseller".
"For information about how to purchase the Multisim VHDL simulator, visit the Electronics Workbench home page at http://www.electronicsworkbench.com"
The version number says 5.15a. This sounds like it may be old and not what your after. It problably would be best to contact NI or look on their website to see what may be available. It may be that you can purchase this as an add-on for Multisim 10, but I am not certain of that.
Sorry I couldn't help more.
Kittmaster's Component Database
http://ni.kittmaster.com
Have a Nice Day

Multisim ac analysis for simple resonant circuit gives wrong answer

Hello,
I tried to run a simulation of the attached simple tank circuit and the multisim results are wrong (don't match hand calculations or microcap simulation results). I tried experimenting with simulation settings with no effect. Can you help me resolve?
-Steve
Attachments:
NI Question1.pdf ‏241 KB

Hi Steve,
Run attached circuit, I was able to similar results as Microcap. This screen shot shows the AC setup I used just in case you are not running Multisim 13.
Tien P.
National Instruments
Attachments:
AC.ms13 ‏59 KB
AC.PNG ‏18 KB

I have an iMac that I purchased back in 2010 and over the past 9 month or less my computer just started shutting down while someone was in the process or working on it. What could this come from? Is there a simple solutions to this problem?

I have an iMac that I purchased back in 2010 and over the past 9 month or less my computer just started shutting down while someone was in the process or working on it. What could this come from? Is there a simple solutions to this problem?

Which model iMac do you have? http://support.apple.com/kb/HT1758 How to identify iMac models
Which OS is currently installed?
Check out KB Articles: http://support.apple.com/kb/HT3964 Intel-based Macs: Resetting the System Management Controller (SMC) and http://support.apple.com/kb/HT1379 Resetting your Mac's PRAM and NVRAM
If not of the above works and you have AC, call them. Let them deal w/it. Otherwise, take your iMac down to your local AS or an AASP. Diagnostic testing is FREE!
You can also research for a solution on YouTube's "How To" website and iFixit.

Frequency Modulation circuit simulation in Multisim Using 566.

How can I get Frequency Modulation circuit simulation in Multisim Using 566? In Multisim I dont have IC 566.. And I have attached the image of the circuit i want... I dont want to use FM signal source directly.
Attachments:
FM CIRCUIT USING IC566.PNG ‏21 KB

Hello,
This component is not available in Multisim; I tried to locate a SPICE model for LM566 with no luck. It seems that the component is obsolete now.
Take a look of this old forum post, it explains an alternate method to build the FM circuit.
Hope this helps.
Fernando D.
National Instruments

Simple Led Display

Hello, I am new in labview iam learning only 2 weeks. If someone have little time to help i will be realy thankful. I need help with simple led display. Display should have maximum 20columns and 40rows, user should choose the size of display. After run program, leds should be shine sequentially : every second row, every second column, 4 corners leds and middle led.
I wieved all tutorials from NI on youtube i understand basic items but i realy dont know how to create this program.
I will be realy thankful if someone can help me with that.
Sorry for my bad English thats not realy my cup of coffe

First, the term is "tea". "Not my cup of tea." If it were an American term it would probably be coffee -- or something stronger, but it's British, so there you are...
Second, so the idea is that the user will set the size of the array before running the program, and then light up the LEDs in the patterns you identified? This means that you will have to determine the size of the front panel array using property nodes, then generate the binary patterns on the fly -- very tricky of your instructor..
Third, you will need to provide some sort of timing to keep the loop from running too fast.
Fourth, it would probably work well to structure the whole thing as a kind of state machine.
Mike...
Certified Professional Instructor
Certified LabVIEW Architect
LabVIEW Champion
"... after all, He's not a tame lion..."
Be thinking ahead and mark your dance card for NI Week 2015 now: TS 6139 - Object Oriented First Steps

EM simulation problem

Hi,
I have been trying to solve this EM simulation problem in the attached project (from a customer) but with no luck. I have tried changing the interpolation/passivity options, switching to APLAC simulations, different AXIEM settings with/without AFS, #sim points, DC frequency in the EXTRACT block etc but the simulation just wouldn't complete without error. The consistent error is 'Vector fitting failure' for which I could find no help. I am sure there is something I'm missing here, would someone be kind enough to take a quick look and tell me how to go about solving this problem ?
Thank you!
Attachments:
LNA_grndpr_finfab1_toAWR.zip ‏94 KB

Hi,
I am looking into this issue right now. The ports are set up wrong on your extracted document, so I am trying to figure out a way to set them up correctly. I will get back to you once I find out more.
Thanks,
Ideen

Simulate just a simple LM324 circuit but the result is incorrect

Hi guys,
I have a problem with LM324 simulation.
Here is my circuit:
I simulated it but the output of the opamp was just a DC signal which is theoretically incorrect.
Pls help me to find out where the problem is.
Thank you.
Solved!
Go to Solution.

supsup wrote:
Check up connections of power supplies with the GND.
Thank you for your answer. The +12V power supply was not connected to GND causing the incorrect result.
regards,

Parallel LED circuit not reading correctly

Good day,
Can anyone tell me if there is something wrong with this circuit or if the software is acting funny?
I have a voltage source positive going into 3 parallel circuits. Each circuit contains a 30 ohm reisiter connected in series to 3 parallel LED's. The LED's have a forward operating current of 20mA.
the first branch is reading 1.9V the second branch is reading 2.2V and the third branch is reading 3.4V across the parallel LED's.
hoping it is a bug I introduced or maybe I am misunderstanding how to connect the components properly.
I have a file with a cap screen to show how it is connected
Attachments:
multisim circuit.doc ‏138 KB

1. Please create .png files from your screenshots and insert them directly into the post. The little Tree icon in the toolbar just above the text box where you type your message inserts images. Some people on the Forum will not open attachements in other file formats.
2. Real LEDs have different voltage drops for different colors due to different chemical composition. Also the parallel LEDs (at least real ones) would have slightly different VI characteristics so that each of the three LEDs(of the same color) would have different currents and, thus, different light output.
3. It is not clear what your intention is. Normally LEDs are connected in series so that the same current flows through each (same color). Rather than fixed resistorrs use some king of current regulating circuit to adjust the current in each series string to get your RGB effects. Note that you will have very little "headroom" between the source (V1) and the series string of blue LEDs (~10 V).
Lynn

Rectifier simulation problem in multisim

Hi, i've got a problem with my simulation results in Multisim. Why does it cut the voltage to <100V after the rectifier (see attached image)? I think on this computer is an old version installed but thats should be no reason for such behaviour.
When i build the rectifier out of 4 discrete diodes, it works.
Best regards,
hase
Attachments:
multisim.PNG ‏39 KB

Hase,
I checked the spice model for the rectifier that you are using and got it to work. I attached the picture that shows which variable you have to modify, it was set to 100V... that is why you would get that fuzzy thing going on... according to the datasheet it should work up to 1000V right?...
How to fix it.... double-click on the component... then from the value tab, click on the Edit Model button, and then on the spice text scroll down until you see the variable that is shown on the attached picture, you should see that it shows 100, change it to 1000. And then click on Change Part Model to finish. Give that a try, it should work.
Nestor
National Instruments
Attachments:
rectifier.JPG ‏23 KB

Small problem led to big problem

I had a few contacts that existed on my Centro which did not exist on my desktop. So I contacted the Palm Chat Support. The person who helped me had me perform several things which eventually led to my phone getting stuck in a loop. Things were not getting better so I asked to be transferred to a supervisor. The supervisor told me the only solution was a hard reset. I finally agreed to this. Now when I reinstall any applications (not third-party) such as calendar or address book, my phone won't come on. I can see the calendar or the address book but when I go to turn on the phone, it goes back into the endless loop. A soft reset will not take it out of the loop, only a hard reset. When I do a hard reset, I then have the ability to use the phone again but I have no data in my calendar, address book, etc. So essentially I have either a PDA or a Phone--but I can't have both. This started as a very small problem (a few missing contacts which I could have probably/should have probably just manually entered into the desktop). Now I have a very big problem, simply b/c of what I was directed to do by Support. Is there any hope?
Post relates to: Centro (AT&T)

There could be to issues going on here that you are having this result. One thing could be corrupted data such as your contacts or calendar, the other could be corrupted programs that are coming back from a hotsync.
The first I would like to troubleshoot as it is the easiest. To fix this what we need to do is hard reset your device. The instructions to do that is here http://kb.palm.com/wps/portal/kb/common/article/887_en.html this tells you how to do all types of resets. Also, what we need to do is rename your backup folder. What this folder is, it hold all your programs from the last time you synced your PC. On your computer go here
Palm Desktop 4.2 and below
My Computer--> C drive --> Program files --> Palm/PalmOne--> your hotsync username
Palm Desktop 6.2.2
My Documents/Documents --> Palm OS Desktop --> your hotsync username
Right click on your backup folder and rename it to "backupOld". Resync your device to the same user name and you will get all your contacts, calendar, tasks, and memos.
You can install the programs again but make sure they are compatible with the device. Also try one program again and wait 24 hours to see if the same thing happens again. This way you know what program is causing the issue.
If you have any questions about this or if this does not work please post back.

Controlling the ouput of my parallel port to control a simple LED display

I am trying to produce a running light (using 8 LEDs) from my parallel port. How should I start if I want to program using Java. Can I anyone give me a simple program to start with?

I am trying to produce a running light (using 8 LEDs) from my parallel port. How should I start if I want to program using Java. Can I anyone give me a simple program to start with?

Simple Finder/Parental Controls Problem

I recently did an erase and install on my eMac and am now having problems with Simple Finder and Parental Controls.
I have an account set up for my daughter and I want to have Simple Finder running with about a half dozen or so applications for her to use. Prior to the erase-and-install, I had this set up and running fine. But now, even though I select all the programs I want under the Parental Controls preferences, only three show up (Safari, Dictionary, and TextEdit).
I tried deleting and re-creating the account, repairing permissions, turning around twice and clicking my heels together, etc. with no success.
Any ideas? Thanks!

I ran disk utility and repaired the permissions--is that similar to what you suggest?
When I did a erase-and-install of Leopard, I assume that it ran through a disk inspection and repair routine. But perhaps something more is needed.

IOS Simulator problem

I'm using the latest OS version OS Mountain Lion, and the latest xCode version. My problem is, when I use xCode, to test iOS Simulator, ios simulator won't run. The program will open but it will freeze. I have been searching for solutions but no luck. Can someone help me please. Thank You.

Maybe you should be posting here:
https://discussions.apple.com/community/developer_forums

IMac backlight OR LED Screen Panel Problem.

So for about 6 months now i've noticed these 'smudge marks' people have been talking about behind the glass screen in my iMac 27" which is a late 2011 model (about 13/14 months old) and was bought new fro the iMac store.
Then about 6 weeks ago i started having problems with what i thought was the backlight. After 5 minutes or so of being on my iMac, the screen would all dim a little and sometimes flicker for a fw seconds until it halted at a certain level of brightness (which i couldnt make brighter with the brightness volume buttons.) It became more frequent over the weeks and some times went completely black but i waited to take it into Apple because i live in Leeds UK and i knew there was a new Apple store being opened (Thursday 21st March 2013). Normally i would have to travel to the Meadowhall Centre (Sheffield).
So sure enough, i went in on the open day and they took in my iMac telling me it was the backlight. They quoted me £109 including VAT whih i was willing to pay. I had a phonecall today 25/3/13 from the store telling me they had replaced the backlight and the problem was still occouring so they would need to replace the LED Panel. I was also told this would cost me over £300 + VAT! No way can i afford to pay that and i'm probably not alone when i say it took me long enough to save for the iMac itself! Theres obviously a serious issue with the backlights and LED Panels of iMacs dating back since before the iMac models first came about. I don't smoke, one of the 'Geniuses' in the Apple store even commented on how well it had been looked after, there are no radiators near my studio, it is very well ventillated and isnt over used, so this obviously isnt a case of not looking after it propely. I don't understand why i have to pay over £300 if this is a MAJOR fault with apples product and not mine. Tomorrow i have to pick up my iMac (still broken) and simply work with the problem which i'm pretty sure soon, will be almost impossible if the screen continues to go black and fail on me.
Recap:
My questions are these.
What is causing the problems with the iMac backlight/LED Panel?
Why have Apple not done anything about this fault since it's been going on years now?
Why should i have to pay over £300 to fix APPLES FAULT.
And finally, has anyone here won an argument similar to this that were out of warranty and not had to pay?
Thanks,
Billy.

Hi Billy, sad, isn't it!?
Some have paitiently worked their way through Applecare to get to a point where you can ask to speak to a customer service rep, & some have gotten satisfaction that way.
On the LCD, I wonder if it isn't that LCD cable problem...
http://forums.macrumors.com/showthread.php?t=1049431

Simple LED Circuit Simulation problem?

Similar Messages

Maybe you are looking for