Usb-tc01 cold junction noise?

Hello,
I am using USB-TC01 thermocouple devices a lot from NI, and I have a practical question.
The scenario: I "Peltier-control" an electrical cabinet's (1 cubicmeter) temperature, I measure the temperature with the above sensor. I feed this value into a PID VI, which is driving a current source connected to Peltier-modules.
Sampling rate (also for PID) is 1 second. I can reach pretty nice temperature stability, between 0.02 - 0.04 Celsius standard deviation calculated from 600 samples. I have tuned my PID using the Ziegler-Nichols rules.
So basically I am satisfied, but one thing I notice on the measured USB-TC01 signal. It sometimes, randomly "jumps" up and down, with an amplitude of ~0.05 Celsius. Is this the effect of the cold junction compensator? I have attached a figure to show what I mean.
Sometimes, for certain intervals, which can be even like 10 minutes, I do not see these "jumps". In these intervals, the stability reaches +-0.02 Celsius.
Including the noisy parts, the stability drops with a factor of 2 (+- 0.04 Celsius).
I guess this does not mean real jumps in the real temperature, so this is an artifact. My question is that, do I need to filter these jumps somehow to have an even better PID, or am I already at the practical limit using this sensor? I tried to put a FIR filter before the PID VI, but I did not notice a significant improvement...
Thanks for advice!

well, i have managed to test another sensor (the sensor which gave the posted data is recently used and running, cannot take it) in a less noise environment. I see continuous noise, with a pp amplitude of 0.05 degrees, what is a value specified for the sensor as you mentioned previously. Maybe the first sensor is defect in a way, it sometimes has less baseline noise?
Actually it is an interesting question: NI produces a lot of these sensors, and I guess they state the "worst possible" noise value in the spec. papers. What about if a certain number of the sensors are better? Well, I have no idea if this makes any sense...
when I have the chance, I will take the first sensor to the same less noisy location, and I will compare them. I am very interested what I will see...

Similar Messages

How to do Cold Junction Compensation using USB-6218

I'm pretty certain that the DAQ itself doesn't have a built in thermistor for CJC so I wanted to see if I could potentially use an extra thermocouple to account for it. The whole purpose of this section of the DAQ program I'm building is to measure engine temperatures. Can I use an extra thermocouple that isn't measuring anything for cold junction compensation?

Ok so I tried messing around in MAX and I see where you can set up a channel
for CJC. There’s only one problem. I’m not sure how to set up the CJC
thermocouple. For the other thermocouples I see where I can set the CJC Source
to CJC Channel and then select a MAX task.
I’m not sure how to set up the CJC task. I go to create new task – Add Channel
– Thermocouple – Select Channel – and then choose the channel that the
thermocouple is wired in to. Now I have the follow options that I set.
Max – 100 deg C
Min – 0 deg C
Thermocouple type – K
CJC Source (I have three options)
Built-in
Constant – specify constant CJC value
CJC Channel – specify channel
I’m not sure which of these three I should pick when setting up the CJC thermocouple.

USB-TC01 specification request for clarification

Dear People,
We would like to clarify some accuracy data on temperature measurements carried out by using the USB-TC01 + J-type thermocouple.
We are just not sure how to use the given spec data to predict the available accuracy (and resolution) in the following scenario:
the sensor box is placed together with the J-type wire in a lab room, and the room temperature can vary between 20 and 25 Celsius degree. What is the reachable accuracy and resolution in this case (since the cold junction comp. circuit is "also in the room")?
By the way, we need to measure temperature in our experiment with at least 0.05 Celsius accuracy and the same resolution.
If USB-TC01 is not able to fulfil our needs, can you recommend us a different NI product(s)?
Thanks very much!
Solved!
Go to Solution.

the thermocouple is also from NI (you can buy it together with the USB-TC01 "box").
But I think the "bottleneck" in resolution/accuracy is the cold junction compensation electronics, not the thermocouple?
I understand that, mostly people do not need high accuracy, but when we need, it could be nice from NI to offer an out-of-the_box cheap/compact solution. Like a thermistor bridge built together with a precision voltage reference
I guess this such a thermistor bridge approach can definitely reach much better accuracy and resolution. But NI offer only very expensive hardware for such an assembly (PXIs, etc...).
I have found this for RTD platinum:
http://www.ni.com/pdf/products/us/3daqsc350-351.pdf
The accuracy is regarding the pdf spec file:
+- 0.3 + 0.005*T, so at room temp, the accuracy is about +-0.4 Celsius. Not enough. But for this, you need additional hardware to measure 3 or 4 wire resistivity.
Hmmm, maybe I am mixing again accuracy and resolution? We could live with this accuracy, since in our case, the absolute value is not that important. The resolution what is really important.
I guess with an accurate resistivity measurement, we could reach even 1E-4 Celsius resolution? (if i remember well for a paper read some time ago...)

Temp Measurement in USB TC01

Hi All,
I have an MFC application that is full functional & I am trying to add some functionality for which I need to get the temperature from a NI USB TC01. I have added the NIDAQMx.h header & the associated library. All I want is a function from this library which gives me the temperature in Degree C,which I can use for some other things in my application. I am able to query the device for basic parameters like S/N & other things, however when I try to use the function DAQmxGetCalDevTemp(), all I get is a 0 in my Float64 data. What am I doing wrong, could some1 point me in the right direction? I am new at using this library, any guidance would be much appreciated.
<CODE SNIPPET>
float64 data;const char deviceName[]="dev1";
int32 mytemp= DAQmxGetCalDevTemp( deviceName, &data);

//This is the example C Code incase someone wants to see
* ANSI C Example program:
* ContThrmcplSamps-IntClk.c
* Example Category:
* AI
* Description:
* This example demonstrates how to make continuous, hardware-timed
* temperature measurement using a thermocouple.
* Instructions for Running:
* 1. Specify the Physical Channel where you have connected the
* thermocouple.
* 2. Enter the Minimum and Maximum temperature values in degrees C
* you expect to measure. A smaller range will allow a more
* accurate measurement.
* 3. Enter the scan rate at which you want to run the acquisition.
* 4. Specify the type of thermocouple you are using.
* 5. Thermocouple measurements require cold-junction compensation
* (CJC) to correctly scale them. Specify the source of your
* cold-junction compensation.
* 6. If your CJC source is "Internal", skip the rest of the steps.
* 7. If your CJC source is "Constant Value", specify the value
* (usually room temperature) in degrees C.
* 8. If your CJC source is "Channel", specify the CJC Channel
* name.
* 9. Specify the appropriate Auto Zero Mode. See your device's
* hardware manual to find out if your device supports this
* attribute.
* Steps:
* 1. Create a task.
* 2. Create a Thermocouple (TC) temperature measurement channel.
* 3. If your device supports Auto Zero Mode, set the AutoZero
* attribute for all channels in the task.
* 4. Call the Timing function to specify the hardware timing
* parameters. Use device's internal clock, continuous mode
* acquisition and the sample rate specified by the user.
* 5. Call the Start function to program and start the acquisition.
* 6. Read N samples and plot it. By default, the Read function
* reads all available samples, but you can specify how many
* samples to read at a time and the timeout value. Continue
* reading data until the stop button is pressed or an error
* occurs.
* 7. Call the Clear Task function to clear the Task.
* 8. Display an error if any.
* I/O Connections Overview:
* Connect your thermocouple to the terminals corresponding to the
* Physical Channel I/O Control value.
#include <stdio.h>
#include <NIDAQmx.h>
#define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else
int32 CVICALLBACK EveryNCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData);
int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData);
int main(void)
int32 error=0;
TaskHandle taskHandle=0;
char errBuff[2048]={'\0'};
// DAQmx Configure Code
DAQmxErrChk (DAQmxCreateTask("",&taskHandle));
//DAQmxErrChk (DAQmxCreateAIThrmcplChan(taskHandle,"","",0.0,100.0,DAQmx_Val_DegC,DAQmx_Val_J_Type_TC,DAQmx_Val_BuiltIn,25.0,""));
DAQmxErrChk (DAQmxCreateAIThrmcplChan(taskHandle,"Dev1/ai0","ai0",0.0,100.0,DAQmx_Val_DegC,DAQmx_Val_J_Type_TC,DAQmx_Val_BuiltIn,25.0,"ai0"));
//DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandle,"",10.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandle,"",10.0,DAQmx_Val_Rising,DAQmx_Val_ContSamps,1000));
DAQmxErrChk (DAQmxRegisterEveryNSamplesEvent(taskHandle,DAQmx_Val_Acquired_Into_Buffer,1000,0,EveryNCallback,NULL));
DAQmxErrChk (DAQmxRegisterDoneEvent(taskHandle,0,DoneCallback,NULL));
// DAQmx Start Code
DAQmxErrChk (DAQmxStartTask(taskHandle));
printf("Acquiring samples continuously. Press Enter to interrupt\n");
getchar();
Error:
if( DAQmxFailed(error) )
DAQmxGetExtendedErrorInfo(errBuff,2048);
if( taskHandle!=0 ) {
// DAQmx Stop Code
DAQmxStopTask(taskHandle);
DAQmxClearTask(taskHandle);
if( DAQmxFailed(error) )
printf("DAQmx Error: %s\n",errBuff);
printf("End of program, press Enter key to quit\n");
getchar();
return 0;
int32 CVICALLBACK EveryNCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData)
int32 error=0;
char errBuff[2048]={'\0'};
static int totalRead=0;
int32 read=0;
float64 data[1000];
// DAQmx Read Code
DAQmxErrChk (DAQmxReadAnalogF64(taskHandle,-1,10.0,DAQmx_Val_GroupByScanNumber,data,1000,&read,NULL));
if( read>0 ) {
printf("Acquired %d samples. Total %d\r",read,totalRead+=read);
fflush(stdout);
Error:
if( DAQmxFailed(error) ) {
DAQmxGetExtendedErrorInfo(errBuff,2048);
// DAQmx Stop Code
DAQmxStopTask(taskHandle);
DAQmxClearTask(taskHandle);
printf("DAQmx Error: %s\n",errBuff);
return 0;
int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData)
int32 error=0;
char errBuff[2048]={'\0'};
// Check to see if an error stopped the task.
DAQmxErrChk (status);
Error:
if( DAQmxFailed(error) ) {
DAQmxGetExtendedErrorInfo(errBuff,2048);
DAQmxClearTask(taskHandle);
printf("DAQmx Error: %s\n",errBuff);
return 0;

Cold junction compensation

Hello
We have just bought a new NI card (PCI-6052E) connected to a terminal block
(CB-68LP), and so we now have to set-up the cold junction compensation
manually (previously we were using a SCXI-1303 which had it built in).
I would just like to check that the method which we have devised will work.
We are proposing to acquire a thermistor (with known temperature versus
resistance behaviour) and put this in series with a resistor. We would then
put a voltage across these two components and have the voltage drop across
the thermistor as one of the inputs on the terminal block. In the
Measurement and Automation explorer we will set up this channel(called
"cjc") as being a voltage input and tick the box which says it is a
temperat
ure input. We then apply a scaling equation which converts this
voltage into temperature.
We then set up our thermocouple channels in the Measurement and Automation
explorer, and in the CJC source box we say it is user-supplied and make the
user cjc channel the one we made earlier ("cjc").
Is this the correct method of doing this?
Thanks!
Jon Atkinson

Hi Jon -
I'll leave the details of the software to those more familiar with
them. I will offer a bit of comment re. the thermister.
Be a little careful with the thermistor approach. Thermistors suffer
from self-heating problems so the value of resistor chosen is important
to limit these effect.
For a few cents more, it might be worth investigating any of the IC
devices that supply a current or voltage proportional to temperature.
There are also dedicated three terminal cold junction ICs that can be
wired-in fairly simply.
Sincerely,
John
"Dr Jon Atkinson" wrote:
> Hello
>
> We have just bought a new NI card (PCI-6052E) connected to a terminal
block
> (CB-68LP), and so we now have to set-up the cold junction compensation
> manually
(previously we were using a SCXI-1303 which had it built in).
>
> I would just like to check that the method which we have devised will
work.
> We are proposing to acquire a thermistor (with known temperature
versus
> resistance behaviour) and put this in series with a resistor. We
would then
> put a voltage across these two components and have the voltage drop
across
> the thermistor as one of the inputs on the terminal block. In the
> Measurement and Automation explorer we will set up this channel(called
> "cjc") as being a voltage input and tick the box which says it is a
> temperature input. We then apply a scaling equation which converts
this
> voltage into temperature.
>
> We then set up our thermocouple channels in the Measurement and
Automation
> explorer, and in the CJC source box we say it is user-supplied and
make the
> user cjc channel the one we made earlier ("cjc").
>
> Is this the correct method of doing this?
>
> Thanks!
>
> Jon Atkinson
>
>
Sent via Deja.com
http://
www.deja.com/

Can I make a simple voltage recording when SCB-68 is configured for Cold Junction Compensation?

Hi everyone,
I am using a 6221 PCI card and SCB-68 connection module. I have set the SCB-68 module switches so that the 5 thermocouples I have connected between AI1 and AI5 are using the Cold Junction Compensation of AI0. Everything works fine.
Could someone tell me if the differential inputs left AI6 and AI7 can be used for recording another kind of sensor (nothing to do with a thermocouple) ? I suppose I just need to set those 2 inputs to a simple voltage recording function? The previous switches settings enable to do this simple recording ?
Thanks,
User
Solved!
Go to Solution.

Hi Bruce,
Thanks for your answer and your advice. So I will use my free channels for other sensors.
Concerning your other remarks , I have planned setting the DAQ assitant at 100 samples and 1KHz for the thermocuples. Making an average of the 100 samples for each channel gives a good result from what I have seen in my last test. After this, with another DAQ assistant I am making some other kind of recording at another speed. I know this is not optimized using DAQ Assistant but loss of time and simultanity isn't a problem for me in this project.
However if I had used only one DAQ Assistant for my thermocouples and for the other sensors, a part from the rate vs thermocouples problem, not having the same ranges could have been a problem?
I also don't understand the channel order you mentioned. Still using a DAQ Assistant in what way would this effetc the measures?

Cold junction on SCXI with CVI

(Using SCXI 2000 chassis and 1200 DAQ, 1102 Thermocouple module):
Is it possible to read the cold junction temperature during the
same AIStartAcquisition loop in which you scan a number of channels?
i.e. can you use, for example the channel string
"OB0!Sc1!md2!cjtemp,0:11"
to acquire both the cold junction reading AND channels 0 to 11 ? Or do you
have to run two seperate Acquisitions simultaneously??

Hello Rabi,
Yes it's possible to read both the cold juntion and channels 0 through 11.
You would write something like this in the string:
"OB0!Sc1!md2!cjtemp,OB0!Sc1!md2!0:11"
I tried it a while back and I got it working. But I don't remember the exact
syntax of the
string. Let me know if this doesn't work for you.
Azucena
"Rabi B" wrote in message
news:[email protected]..
>
> (Using SCXI 2000 chassis and 1200 DAQ, 1102 Thermocouple module):
>
> Is it possible to read the cold junction temperature during the
> same AIStartAcquisition loop in which you scan a number of channels?
> i.e. can you use, for example the channel string
> "OB0!Sc1!md2!cjtemp,0:11"
> to acquire both the cold junction reading AND channels 0 to 11 ? Or do
you
>
> have to run two seperate Acquisitions simultaneously??

Comment modifier l'intervalle d'acquisition des données sur USB-TC01 ?

Bonjour,
L'intervalle d'acquisition sur l'USB-TC01 (S/N : HB1144942) que je possède est de 1 seconde. Pour mon application : Enregistrement de la courbe de température de cuisson d'un four à céramique, je voudrai pouvoir modifier à volonté cette valeur. Bien évidemment je ne possède ni Labview ou équivalent ni les compétences pour développer moi-même cette simple application.
J'ai lu dans l'un des forums que cette possibilité existait dorénavant et j'ai cru comprendre qu'en téléchargeant un nouveau firmware 1.0.1 (NIDAQ911fo) je pouvais solutionner mon problème. J'ai téléchargé (c'est très long) et installé cette mise à jour. En fin d'installation le systeme me dit que c'est impossible que cette version est antérieure à celle présente sur mon ordinateur.
Merci d'avance à ceux qui pourront prendre un peu de temps pour m'aider
Alain AUCH
Tel : 06 26 17 53 10

Bonjour Victor,
Merci pour votre réponse.
Je ne souhaite par paramètrer plus de 4 sample/s mais plutot moins 1 sample/minute voire toute les 2 minutes me conviendrai parfaitement.
Sur le lien que vous me communiquez : Do More with Your NI USB-TC01 je n'ai rien trouvé qui me permette de mettre à jour le firmware à l'exception du lien de téléchargement déjà évoqué et qui ne fonctionne pas pour les raisons que vous m'avez expliqué.
Avant de vous envoyé mon premier message, j'avais trouvé et téléchargé la mise à jour NI-DAQmx version 9.1.1 (NIDAQ911Fo.exe). Elle est très longue à charger (3 à 4 heures), longue à installer et à la fin lorsque j'ai voulu updater, mon système m'a sorti un message disant qu'il ne pouvait pas mettre à jour car la version qui était déjà installée était une version ultèrieure à celle que je venais d'installer. Je n'ai pas noté les termes exact de ce message. Aussi comme j'avais supprimé ce logiciel de mon disque je vais retélécharger la mise à jour et recommencer l'opération. Et je vous informerai du résultat.
Pendant que j'y suis, une autre question sur ce même USB-TC01 :
Lorsqu'il fonctionne, le graphique affiché à l'écran porte en abcisse le temps et seulement une plage de temps de 60 seconde est visible. Y-a-t'il un moyen pour faire afficher l'ensemble de la courbe à partir de t0 ? Faut-il développer un programme spécial et pour cela acheter Labview ou autre ?
Mon application est le suivi de la cuisson de céramiques dans un four électrique qui est commandé par un petit automate qui contrôle la chauffe. Cette montée en température se fait en plusieurs étapes avec des pentes différentes et des périodes intermédiaires de stabilisation.
C'est pour cela que je souhaiterai afficher à l'écran la courbe complète du début de la cuisson jusqu'à la fin (en tout de 7 à 13 heures).
Avez-vous une solution à me proposer ?
Je précise que de nombreux professionnels et AMATEURS de poterie et de la céramique ont ce même problème de suivi de la courbe de montée en température. Si votre USB-TC01, qui est compétitif au niveau prix, pouvait apporter une solution il y aurait sans doute un marché pour NI dans ce domaine. Je serai moi-même prêt à en faire la promotion sur les forums dédiés à la céramique d'art.
Merci d'avance
Cordialement,
Alain AUCH

6016 cold junction setup

I am trying to use the 6016 to measure temperature in a chamber. I am aware that there is no built-in compensation network in there. So, my reading is all over.
I would like to use another thermacouple outside of the chamber as reference for the thermacouple that is inside of the chamer. I understand that the reference might drift a bit depending on the room temp, but at least it will be better than not using it.
How can I implement this? I using the DAQmx Assistant to do this. And at the bottom, where I set up the CJC, I choose channel but what do I type in there? 14 since reference channel is 14. I keep getting message saying that where is no such channel.
Or is there a better way to it? Can I place a know voltage in one of the ports to create a reference. Again, how to I tell the DAQ Assistance to use this as reference.

On Apr 21, 7:27 pm, hrh1818 <[email protected]> wrote:
> On Apr 21, 2:10 pm, randyram <[email protected]> wrote:
>
> > I am trying to use the 6016 to measure temperature in a chamber. I am aware that there is no built-in compensation network in there. So, my reading is all over.
> > I would like to use another thermacouple outside of the chamber as reference for the thermacouple that is inside of the chamer. I understand that the reference might drift a bit depending on the room temp, but at least it will be better than not using it.
> >  
> > How can I implement this? I using the DAQmx Assistant to do this. And at the bottom, where I set up the CJC, I choose channel but what do I type in there? 14 since reference channel is 14. I keep getting message saying that where is no such channel.
> >  
> > Or is there a better way to it? Can I place a know voltage in one of the ports to create a reference. Again, how to I tell the DAQ Assistance to use this as reference.
> >  
> >  
>
> With you 6016 located outside of your chamber and your thermocouple
> located inside your chamber connecting a second thermocouple located
> outside the chamber to your 6016 will not gain any thing. The output
> from a thermocouple is proportional to the difference in temperature
> of the two junctions. In the setup you propose the two junctions will
> be at the same temperature and will produce approximately zero output
> voltage.
>
> If your room temperature variation is relatively small you could
> insulate the terminals of your 6016. The object of the insulation is
> to dampen short term temperature excursions. Another possibility is
> to use a temperature controlled oven to maintain your reference
> junction at a constant temperature. Frequently these ovens are
> operated at 150 degree Fahrenheit. A third possibility is a self
> powered reference junction. See.http://www.omega.com/ppt/pptsc.asp?ref=LXCJ&Nav=temk03
>
> Howard
Another possibility is to use a semiconductor temperature sensor to
measure the temperature of your cold junction and then use the output
of the sensor to compensate your thermocouple readings for room
temperature variations. See:
http://www.temperatures.com/semivendors.html for a list o vendors who
manufacture semiconductor temperature sensors.
Howard

USB-TC01

はじめまして。
Windows8で、VisualC#2012を使い、USB-TC01の制御したいのですが、方法が分かりません。
知人から、NI USB-TC01 Thermocouple Measurement Device.pdfを貰い、参考にしてるのですが、
5章21頁で書かれてるエラーが消えずに困っております。
何かアドバイス願えないでしょうか？

エラーは解消できたのですが、
サンプル通りに記述すると、実温度と差異が10℃位あります。
何か設定抜けなど有るのでしょうか？
以下、サンプルコード
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using NationalInstruments;
using NationalInstruments.DAQmx;
namespace TC01_DAQ_Example
public partial class Form1 : Form
public Form1()
InitializeComponent();
private void btnGetData_Click(object sender, EventArgs e)
Task temperatureTask = new Task();
AIChannel myAIChannel;
myAIChannel = temperatureTask.AIChannels.CreateThermocoupleChannel(
"Dev1/ai0",
"Temperature",
0,
100,
AIThermocoupleType.J,
AITemperatureUnits.DegreesC,
25
AnalogSingleChannelReader reader = new
AnalogSingleChannelReader(temperatureTask.Stream);
double analogDataIn = reader.ReadSingleSample();
txtTempData.Text = analogDataIn.ToString();

USB-TC01 and DAQ assistant

Hi
When I plug my USB-TC01, I can use the .exe example in the module but with DAQ Assistant in LabVIEW I don't see it. When I use MAX, I don't see it.
Do you know where is my problem ?
Thanks.

I am sorry to have to add onto a thread that has nothing to do with my question. I have been searching and searching on how to start a new question (but have failed giving myself ~1/2 hr looking). So once again ... sorry to the poster and people following this thread.
Now ... my question is ... why will my PC not boot when the USB-TC01 is plugged in?? I have adjusted everything in BIOS to make sure I am not trying to boot from USB nor CD/DVD drives. Other than that the device works fine once the PC boots. I tried using a self powered USB. I am using XP, Pentium D, 3.2GHz, w/ 2BG RAM. Any help? I will also continue searching on how to post new messages.
Thanks.

PC wont boot when USB-TC01 plugged in

Why will my PC not boot when the USB-TC01 is plugged in?? I have adjusted everything in BIOS to make sure I am not trying to boot from USB nor CD/DVD drives. Other than that, the device works fine once the PC boots. I tried using a self powered USB. I am using XP, Pentium D, 3.2GHz, w/ 2BG RAM. Any help?
Thanks.

Hi,
I have a few questions to gain a little more insight into what is happening:
1. Have you tried booting up with other USB devices connected? If so, does it boot up correctly?
2. Have you tried this on all available USB ports? If so, does it cause the same behavior?
3. Does the USB-TC01 cause other computers to act this way when connected?
Best regards,
Justin Petry
Justin
National Instruments
Product Support Engineer - Conditioned Measurements

USB Microphone headset and noise

Hello there !
I've done a little research on these threads before coming here, but no luck, I found nothing…
Im the owner of a refurbished MBP Penryn 2,5Ghz and a Plantronics Audio 650 USB headset since october.
2 months ago (around this), I've begun to sometimes experience some constant parasite noise with my microphone (Skype chat, Garageband, QuickTime or Übercaster recording).
I though about a fan noise, or power noise… but it appears to be absolutely not predictable.
I have done some tests with temperature viewer and fan speed viewer… on some days after utilisation, I have this noise. The CPU can be at 55°c, GPU at 60/68°c (and some others).
The fans are constantly to 2000 rpm during these issues.
On other tests, like a morning I made my MBP warming, keeping these temperatures, but no noise.
Well, Im at this moment using it with iTunes playing, battery charging, USB mouse and headset connectd, FireWire 800 working, the "noise-temperatures" reached… and no noise with the microphone.
I contacted Plantronics, who asked me to make a crossed test, but I was not able to reproduce it on an Intel iMac or a Titanium G4…
Is there someone here who have some ideas about what is going on ?
I suspected the headset, the hardware, the 10.5.6 update… even my 4 Gb of RAM installed in November… or the dust in the colling access !
But I cant reach a constant parameter to solve this…
Thanks in advance !

OK, thanks for the reply.
I seem to recall that certain device types, like disk drives and audio devices, have a standardized USB interface. That is, no device-specific driver is required (assuming that they design to the standard, of course). I guess then what you're saying then is the iOS devices don't have that standard audio-device driver. I guess that's a not-unreasonable choice on Apple's part.
I suppose another possibility might be somebody making a (small, light, preferably in-line) adaptor from USB audio to 8th-inch pin plug - essentially a very-small, very-simple USB-interfaced A/D-D/A). I looked for such a thing on Amazon, and didn't see anything like that, but perhaps I didn't use the right keywords. Then again, such a device would presumably need a battery, which would probably contradict the "small and light" criteria! :-)

T520's USB ports emit disturbing noise

Hello
Recently I purchased a T520, 4240.
Overall I am satisfied and the computer is working well, there is only one issue which bothers me. I noticed that, when sitting in a quiet room, it emits an unusual noise which resembles a "whine" whenever I connect a mouse or another device to one of its USB ports. However, as soon as all USB ports are open, the whine disappears.
I have tried searching the forum and other websites and the only suggestion is to update bios, however, my current bios is 1,37 and the newest bios (1,38) only addresses issuses such as
- Fixed an issue where specific hard disks might not be detected after resuming
normal operation from standby/sleep state.
- Fixed an issue where an unnecessary fan error message might be shown during boot.
which would not help me. Besides, I want to avoid unnecessary updates to bios because they have ruined my motherboards earlier.
Perhaps this issue of mine seems minor to others, but I cannot easily ignore it as it gives me a headache.
Is there anything else I can do?
Thank you,
Mjallo

Thank you for your replies,
alvinwong,
I doubt it is related to the speakers, assuming that it is what you mean by audio-signal, as it still makes the noise even while the audio is muted. I am not certain though. Is there any way to test it? And if it appears that it, for whatever reason, is caused by the USB's circuit, can it be fixed with software changes?
ColonelONeill,
it is also present when I transfer files to USB drives; furthermore it appears that turning on the bluetooth or inserting an SD card in the card reader causes the "whine" , too.

Usb short now buzzing noise

Presario S5100NX
Hello, believe I caused a short and now there is a humming/buzzing noise coming from inside the pc. Accidentally touched the micro usb side of a cable to the usb hub, computer shutoff/crashed?, and when I turned it on, that buzzing noise began and monitor displayed the Compaq screen with F1 setup and F10 System recovery options. Both option do not respond. Switched keyboards and F1 & F10 still non responsive.
The noise comes from a small black cylinder, with AC-1205G and a plus symbol inside a circle on it's top side. It is located right next to the port that connects the power button and display lights to the board.
Need to know if there is a reset or a fuse. Is the board possible burnt or bad? Can I repair or will I need to take it to a service center?
Help.
This question was solved.
View Solution.

The AC-1205G device is a magnetic buzzer. Considering your venerable old PC (10 years now) has given you many years of great service, it seems an appropriate time to replace it. There is no fuse or reset on the motherboard.
It is highly unlikely that you will be able to find a replacement motherboard as they are no longer manufactured. The current value of the PC ( < $50.00), even in good working condition, is actually not enough to warrant investing any funds to have any work done on it.
Best regards,
erico
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Usb-tc01 cold junction noise?

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