Thanks cliffyk for the idea to improve the Bode Plotter. Indeed, in many cases the range 10Hz…100kHz may be too wide for audio equipment testing purposes. It would be nice to have plotting capability that covers the typical audio range (e.g. 20Hz to 20kHz).
Sorry to say, but the Bode Plotter software code is very old and “quite cumbersome”. I’m afraid that this kind of modification is quite difficult to implement…
On the other hand, the amplifier BW is all the time increasing (e.g. NAD M3 amplifier is specified for frequency response -3dB 3Hz - 70kHz).
This may be a good excuse for keeping the Bode Plotter software “as is”.
Thank you for these detailed measurement results. Indeed, using the AC coupling seems to produce better results.
I’ll try to reproduce these tests with some transformer coil.
Hi cliffyk,
After closer look to the Bode Plotter code I noted that this suggested modification wasn’t so difficult to do as I assumed.
Now there in the View menu will be an option “Audio Range 30kHz”.
When selected, you get nice frequency response plots to 30kHz.
Here one example:
[quote=“VEL255”]Hi cliffyk,
After closer look to the Bode Plotter code I noted that this suggested modification wasn’t so difficult to do as I assumed.
Now there in the View menu will be an option “Audio Range 30kHz”.
When selected, you get nice frequency response plots to 30kHz.
Here one example: [/quote]
Bravo–you have once again outdone your self!
Is this available in the beta version linked to above? If so I know what I will be doing today…
Note: I found it I think–the PCLab2000SE_v3.1(2).zip file?
I made some more tests with a transformer coil and got slightly similar results as you Alain.
I made same run with and without the autoscale.
Without the autoscale the traces seem to be slightly better overlapping.
Also I noted that the CH2 amplitude should be adequate to get stable results.
[quote] I am using an old K8016 that provides very uneven signal amplitudes with frequency. Do you have uneven amplitude if there is no load? [/quote]
Sorry, replying to an old post, I do confirm that you are right. With no load the output of the K8016 generator is reasonably flat. I underestimated the effect of impedance mismarch. However - as mentionned hereabove - the ability to really get the actual Gain = U2/U1 would be a real plus.
Dear Sir,
Regarding the subject of bodeplotter, some questions:
I am owner of a PCSGU250 and would like to study electrical properties of human being skin. Velleman Device, now,meets the standard EN 60601 (I replace the power supply by a EN 60601 device and also separate the USB with a EN 60601 4kV isolator , both devices together in an additional plastic box).
A few questions:
According to your new version of the PC lab2000 Se version 4, what should be the driver to choose ?
Max current should be 0.8 mA, voltage 1 Volt
Is it possible to show me how to connect Channel one and channel 2 phase cables to the skin surface, as I have yet done the interconnection between Channel 2 and the inner function generator of the device. Where to connect neutral cables?
I have to tell you that skin surface impedance change according to the frequencies.
Please find enclosed more details of skin impedance (Extract from “ Revista mexicana de bioingenieria”)
[quote]According to your new version of the PC lab2000 Se version 4, what should be the driver to choose ?[/quote]The software for the PCSGU250 is PcLab2000LT. Here is the link to the downloads page (software and driver): velleman.eu/distributor/supp … u250&type=
[quote]Is it possible to show me how to connect Channel one and channel 2 phase cables to the skin surface, as I have yet done the interconnection between Channel 2 and the inner function generator of the device. Where to connect neutral cables?[/quote]Here is a drawing of the principle how to connect the generator output and oscilloscope inputs for the frequency response measurement:
Here is more detailed drawing how to connect if there is one frequency dependent impedance to measure:
R is a fixed resistor and Z(f) is impedance as a function of frequency.
Selecting the R about the same value as Z, you get good result.
The picture shows also how to connect the neutral leads (green).
Hello,
I use PCSGU250 in Bode mode, however the generator does not scan automatically up to the end (set to different values, mostly 30kHz). It stops latest at 5kHz, sometimes often in between and continues only by pushing “Start”. Above 5kHz only 1 value is taken by one push. What may be the reason for this time-consuming problem? I use V1.08.
Another proposal for improvement: For audio measurements it would be great to include 1/12 octave frequency steps after IEC 60268. By this we would have a homogenious logarithmic distance instead of constant values within one decade.
Thank you for the suggestion to improve the Bode Plotter software.
[quote]It stops latest at 5kHz, sometimes often in between and continues only by pushing “Start”. Above 5kHz only 1 value is taken by one push. What may be the reason for this time-consuming problem?[/quote]This problem can occur if you are using a bus-powered USB HUB to connect the PCSGU250. Also maybe a long or too “weak” USB cable can be the cause. I think the lack of “power” to the PCSGU250 is the root cause of this problem.
The PCSGU250 requires about 400mA current from the USB bus.
This problem may be solved by a driver update too.
You can update the driver to the other version on the installation CD.
Here are instructions how to update the driver: box.net/shared/66aei7j31s
[quote]Another proposal for improvement: For audio measurements it would be great to include 1/12 octave frequency steps after IEC 60268. By this we would have a homogenious logarithmic distance instead of constant values within one decade.[/quote]Now there is this “more professional” octave step mode added to the Bode Plotter of the PCSGU250.
There are following settings available 1/3, 1/6, 1/12, 1/24 and 1/48 octave.
It is possible change the frequency step by selecting the Options menu item Frequency Step Size.
The octave step setting is remembered to the next session.
Thank you for this immediate and wonderful update. I will try it asap. Unfortunately the generator stops are not a matter of power. The used front port of my Acer desktop delivers at least 500 mA with a voltage drop to 4,98 V compared with not load at 5,11 V. The used cable is the one of the PCSGU set and seems not be defective. What other reasons and remedies may be possible?
Sorry. I did not yet try the driver update. Perhaps this will help. I will do it and hopefully operate the mode as intended.
Everything in the PC and cable seems to be OK.
I hope the driver update will help.
BTW: What version of Windows operating system are you using and is it 32- or 64-bit?
The new frequency spacings are running well. However the 5 kHz seems to be a magic stop independent from step size and other parameters. My driver was already 1.0.0.6 as also offered as actual download from your website.
I use Microsoft® Windows Vista™ Home Premium, Version 6.0.6002 Service Pack 2 Build 6002
Prozessor AMD Athlon™ 64 X2 Dual Core Processor 4200+, 2200 MHz, 2 Kern(e), 2 logische® Prozessor(en)
Computer Acer Systemmodell Aspire L5100
I hope this can help to overcome the mystery
btw: Is the waiting time just a means to get stable conditions for critical objects under test?
Please update to the driver v1.0.0.0.
It will most probably solve the problem.
You’ll find the driver on the CD or you can download the driver package from the Velleman site: velleman.eu/downloads/files/ … rivers.zip
Extract the package.
You get two folders as a result.
There in the folder PCSGU250Driver_WinUSB is the alternative driver v1.0.0.0.
Please update to it.
Here you can download the instructions how to update the driver to this version 1.0.0.0 box.net/shared/66aei7j31s
[quote]btw: Is the waiting time just a means to get stable conditions for critical objects under test?[/quote]Yes, you are right.
Thank you, this was the right remedy. The generator now does no longer stop in between.
If you find time for an extra big Xmas gift for audio measurements this could be the generation of 1/3 octave noise signals as another alternative. I have this for the Matlab/Octave use, however I do not know if this can be transferred to PCLAB for PCSGU250. Perhaps it will remain a dream, but the unit is already very useful for me.
It is good to see that the PCSGU250 Bode Plotter is now working OK.
[quote]If you find time for an extra big Xmas gift for audio measurements this could be the generation of 1/3 octave noise signals as another alternative. I have this for the Matlab/Octave use, however I do not know if this can be transferred to PCLAB for PCSGU250. This 1/3 octave noise is interesting.[/quote] Indeed, in the old generator PCG10 there was band limited noise generation. In the PCGU1000 the noise is wide band up to 25MHz. In the PCSGU250 there is no noise function.
[quote]I have this for the Matlab/Octave use[/quote]I’m sorry, my Matlab experience is very limited and very old…
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