I got a strike in my mind that the PC sound card can be used to input sounds and other data, as it converts the signal from Analog to digital and the voltage pulses can be viewed on the PC oscilloscope software.
It takes sounds from a microphone and displays the sound frequencies as voltage pulses.
Most of today's personal computers are equipped with quite advanced soundcards. These soundcards often contain powerful analog/digital converters, able of up to 100 ksamples per second at 16 bit or more. Why not use this capability and build a digital storage oscilloscope around it...?
The microphone input can also be used to input other signals from external electronic circuitry - BUT there is a need to be careful not to input voltages that are too high. The software developer states that the input line voltages need to be 0.7volts or less, and a seperate circuit should be used to attenuate the inputs.
Beware : Not connecting separate circuitry and applying uncontrolled voltages to the PC sound cards can crash your sound card and you have to throw it to your junkyard.
A sound card oscilloscope will give you around 100KHz bandwidth, which is usable for most audio signals and it is a good usable range for analog electronics. It has 3 basic problems:
1) Sound cards are AC coupled, meaning that you will not be able to read signals with frequencies lower than around 10Hz. Also anything lower than 20Hz will get distorted by the AC coupling capacitor.
2) Sound cards have an input impedance that varies around 1KOhm. This means that a circuit with a small signal will get sucked up and you will not be able to read it. (but we can fix this with a pre amp)
3) Sound cards can only safely read around 1.3V peak to peak (we can solve this by scaling the signal)
If you just want to solve #3 and get safe signals to put into your sound card here is a simple solution:
SOLUTION METHOD 1:
Overview
Screenshot
Those parts are usually doubled as all sound cards are two channels - e. g. stereo devices. They may contain other parts, but from the point of view of analog to digital (A/D) signal processing they may not be as important.
Mixer is device joining analog signals from different signal sources into one which is delivered to A/D conversion. Important feature of current mixers is full software control of gain and level of all channels.
A/D converter is usually high precision 16-bit analog to digital converter with maximum sampling rate 44.1 kHz, or 48 kHz.
All (4 ;-) sound cards tested and analyzed have the same feature - all their line-in inputs (and others too) are insulated from DC input by condenser. The reason is, clearly, to set zero level of processed sound signal stable and close to zero. This is, however, a strong limitation for other use, for example for DC measurements.
The situation, fortunately, is not so bad as it seems...
Analyzed, with a good magnifying glass and ohmmeter, LINE IN inputs of four different sound cards - three from Creative Labs, one from Manli:
Inputs of SB16, Audio PCI5000, AWE-64 and CMI8738SX, respectively, are on the Fig. 1.
Fig. 1: SB16, Audio PCI5000, AWE-64 and CMI8738SX LINE IN inputs.
As it can be seen, three inputs are very simple. Input of AWE-64 is a bit more complicated. It contains standard FET operating amplifier, but not condenser at the input. The condenser is at the output, however...
All four sound cards have DC default level at mixer input significantly high. The values displayed don't reflect reality. It was found, that it is close to 2.5V. Direct connection of external DC is not applicable. Is there a solution?
There exists well known application of operating amplifier - differential amplifier. It's schematics (Fig. 2) is quite simple.
Fig. 2: Differential amplifier.
A brief inspection of Fig. 1 shows, that AWE-64 already has operational amplifier. Good new! It is candidate No. 1. Assumed changes will be negligible.
What is needed:
The resulting schematic is on Fig. 3.
Fig. 3: AWE-64 input modification.
With operational amplifier on small PCB, SB16 and CMI8738SX were also checked . The final version had been made with CMI8738SX Manli sound card. Only reason for selection was that it was cheapest and is currently available. Additional to Fig. 3 the schematics contais -5V chip, as sound card has none.
The rest are a bit older models. The results of all sound cards were comparable.
The solution is not limited to AWE-64 and comparables. It seems any sound card can be modified provided small PCB with operational amplifier will be added. At the begining AWE-64 was chosen only due to fact it already has the (pre)amplifier. However for the final solution it was not suitable - in between mother board of home computer changed and ISA slot gone...
To meet our needs we developed original program. It is two channel:
Hardware
The device with manual range switch was equipped to make it a real osciloscope. Its construction is very simple:
Fig. 4: Manual range switch (one channel only).
No special components were used. Dual switch was constructed in small metal box with input bushings. It is connected with LINE IN input by standard shielded stereo cable. Switch takes very little space at the table, PC sits near the table, so no change in the organization in the room was needed.
Software (Can be used in 95 to Win7 )
It was created program to use all information available. It is quite complex one. As it can be seen from Fig. 5, it is dual beam oscilloscope-like device combined with AC/DC multimeter and frequency meter.
Fig. 5: Soundscope main screen.
Soundscope screen has the following parts:
The scope window has:
Single click on scope window activates image save dialog - it allows to save screen shots. Currently supported are BMP, GIF and JPG formats.
Below the scope window there is status bar displaying (sometimes) status messages.
Panel of channel controls on the right side of the scope window contains 2 identical sets of controls for each channel - A and B - (from left to right):
Multimeter & controls panel contains (from top to bottom):
Multimeter window contains two displays - larger and smaller ones - larger one displays voltage/current or raw data depending of calibration/raw data button status. Smaller one displays frequency in Hz.
At the right side there are range switch buttons. They are active only if soundscope is calibrated.
AC measurement is enabled by "Hz" button. When pressed, both windows - multimeter and frequency - display AC values.
Below those multimeters there is sound device selector.
The trigger control group consists of (from top to bottom):
Time base control contains 2 butons in group:
Data saving definition button opens small window for data saving options:
Fig. 6: Data saving definition screen.
Right lower corner contains by control buttons:
Description
Program was created using Borland Delphi 6. No shareware or commercial libraries or components were used. To control mixer it was used excellent free mixer component developed by Vit Kovalcik.
All copyrights of the program are owned by the authors. The noncomercial use of the program is free of any charge. All other use must be consulted with the authors.
Program is based on LINE IN inputs use. It is set to use two-channel 16-bit A/D conversion at 44.1 kHz sampling frequency.
Buffer size of the input sampling is 4096 samples, e. g. measurement frequency is 10.7 measurement per second.
Due to low sound card sampling frequency the highest frequency of the acceptable processed signal is around 10kHz. Higher frequencies are processed too, but the AC accuracy drops down.
Anyway DC measurements can be quite accurate, depending on calibration accuracy, of course and sound device A/D converter quuality.
The main domain of the device use should be, except of use as standard multimeter, DC and low frequency AC measurements.
AC amplitude measurements are achieved by software rectifying - the value displayed is close to effective value of the AC signal.
Frequency measurement is achieved by periods count measurement. As the measurement is sampled by 1/44 100 s, it is also measure of the frequency display accuracy. The smallest measurable frequency is around 20Hz.
Triggering is derived from channel A or B. There is no possibility to have triggered both channels. Triggering level can be set. Trigger level is not dependent on display zero level. Currently only positive levels can be set.
As the signal is sampled, e. g. not continual, the resulting triggered display is usually not fully stable.
Successful use of the program expects proper sound card setup. It is accessible via MS Windows Control panel -> Sounds and Multimedia -> Audio -> Recording setup. For more details check Microsoft Windows help.
An example of sound recording setup parameters.
Hardware modification described in this article, provided properly set, does not influence sound card standard features in any way. The modified card can be still used the standard way.
Calibration
Since the soundscope can be used as no calibrated, it's not its goal. To use multimeter functions it is necessary to calibrate all ranges.
Before calibration is started, it is suggested to measure linearity and sensitivity of the LINE IN input. It can be easily done using voltage calibration circuit described below.
To calibrate soundscope properly it is needed to prepare:
Calibration is three steps process. It consists zero level calibration, sensitivity measurement and measurement ranges calibration, which consists of three identical steps to calibrate voltage ranges and one step to calibrate current range (if used).
First step is zero level calibration. It requires disconnect any external voltages from inputs and connecting both ones with ground. Soundscope is switched to Raw data mode. Average value is read for each channel and written into program INI file.
Second step is sensitivity calibration. It requires connecting potentiometer with external DC voltage to both inputs. Soundscope is switched to "Raw data" mode. Potentiometer is set to minimum and slowly turning to get signal as close as possible to red line above (or belove) zero line. Voltage required and average raw value is read for each channel and written into program INI file. There is only one value for both channels. They should not differ in sensitivity, however.
To calibrate voltage ranges one is expected to use circuit according Fig.7. Use of regulated power source is very convenient, anyway the calibration can be sufficiently done using batteries as power source. In this case small lamp should be used to limit current.
Current range is calibrated with the help of circuit on Fig. 8. It should be noted, that ground bushing is not used. This is possible only if the power source has ground insulated from common ground. If it is not available, battery with lamp should be used.
Fig. 7: Voltage calibration circuit.
Fig. 8: Current calibration circuit.
Program INI file
Program doesn't write anything to the MS Windows registry anymore. All required information is now stored in the INI file. It is standard ASCII text file. To change values in the INI file it is expected to use ASCII editor, Windows Notepad is good enough. Use of Winword may produce non-ASCII file and program will crash.
Program INI file name is soundscope.ini and it resides in the same directory as program file. It has following structure:
There are no special components used, except 11M resistor in switch. However silicon diodes at the input should be fast ones and should have very high resistivity. 1k resistor conducting signal to them and LINE IN should be as small as possible - its function is to be fuse. It should burn to prevent the input from overloading. Diodes should bear the "burning" current, of course.For soldering at the sound card microsolder is needed. Transformer solder must be avoided. A good lens or glasses and a certainty in hand may be needed too...
Be careful when disconnecting input pins from ground (provided sound card has preamplifier already). SMD chips are quite fragile!
Small pieces were glued of universal PCB carrying additional components close to the LINE IN input. All joins we did with insulated thin copper wires.
The overall view of the experimental prototype can be seen on Fig. 9.
Fig. 9: Prototype view.
*) depends on calibration
**) 1s captured WAV file has size 176kB, 1 hour captured WAV file has size 635MB!!, an attempt to capture 9999min WAV file will fill your hard drive for sure...
Screenshot Courtesy : www.qsl.net References : www.techspot.com www.sciencetronics.com www.electronic-engineering.ch
www.qsl.net
It takes sounds from a microphone and displays the sound frequencies as voltage pulses.
Most of today's personal computers are equipped with quite advanced soundcards. These soundcards often contain powerful analog/digital converters, able of up to 100 ksamples per second at 16 bit or more. Why not use this capability and build a digital storage oscilloscope around it...?
The microphone input can also be used to input other signals from external electronic circuitry - BUT there is a need to be careful not to input voltages that are too high. The software developer states that the input line voltages need to be 0.7volts or less, and a seperate circuit should be used to attenuate the inputs.
Beware : Not connecting separate circuitry and applying uncontrolled voltages to the PC sound cards can crash your sound card and you have to throw it to your junkyard.
A sound card oscilloscope will give you around 100KHz bandwidth, which is usable for most audio signals and it is a good usable range for analog electronics. It has 3 basic problems:
1) Sound cards are AC coupled, meaning that you will not be able to read signals with frequencies lower than around 10Hz. Also anything lower than 20Hz will get distorted by the AC coupling capacitor.
2) Sound cards have an input impedance that varies around 1KOhm. This means that a circuit with a small signal will get sucked up and you will not be able to read it. (but we can fix this with a pre amp)
3) Sound cards can only safely read around 1.3V peak to peak (we can solve this by scaling the signal)
If you just want to solve #3 and get safe signals to put into your sound card here is a simple solution:
SOLUTION METHOD 1:
Overview
For simple electronic circuits, it may be sufficient to get a qualitative insight on dedicated electrical signals. This interface circuitry allows to use the line-in input of a standard PC soundcard to be used as a 2-channel oscilloscope.
This setup does not allow for exact measurements, however for some applications, a qualitative insight on dedicated timing or signal characteristics may be obtained.
The interface limits the signals from input channel 1 and 2 to a maximum amplitude of 1.2 V (over-voltage protection circuitry). At the left side of the schematic below, the two input channels for signal measurement and the common ground are shown. At the right side, next to the protection diodes, the connections for the 3.5 mm stereo jack to the soundcard (line-in) are drawn.
The height of the signal amplitude shown within the OSZI can be adjusted with the two trimmers with signal of known amplitude (e.g. a rectified 5V signal). Since most line-in are AC-coupled, pure DC signals are not suitable for calibration of the voltage levels.
The height of the signal amplitude shown within the OSZI can be adjusted with the two trimmers with signal of known amplitude (e.g. a rectified 5V signal). Since most line-in are AC-coupled, pure DC signals are not suitable for calibration of the voltage levels.
Note: There exist now very nice software tools for your PC soundcard (Windows XP) from Sebastian Dunst: AudioAnalyzer & MultiSine.
Schematic
Schematic
 Interface protection circuit for the line-in input at the soundcard. External measurement inputs at the left side, soundcard connection by 3.5 mm stereo jack at the right side. |
 3.5 mm stereo jack for connection to the line-in input at the soundcard |
 Screenshot of data capture of one signal using OSZI software and Windows 95 Note that this is an AC coupled signal (due to the line-in port of the PC), and allows only for qualitative data acquisition. |
SOLUTION METHOD 2:
Preface
PC sound card, standard component of practically all current personal computers, consists, in minimum, of two parts:
- mixer
- A/D converter
Those parts are usually doubled as all sound cards are two channels - e. g. stereo devices. They may contain other parts, but from the point of view of analog to digital (A/D) signal processing they may not be as important.
Mixer is device joining analog signals from different signal sources into one which is delivered to A/D conversion. Important feature of current mixers is full software control of gain and level of all channels.
A/D converter is usually high precision 16-bit analog to digital converter with maximum sampling rate 44.1 kHz, or 48 kHz.
All (4 ;-) sound cards tested and analyzed have the same feature - all their line-in inputs (and others too) are insulated from DC input by condenser. The reason is, clearly, to set zero level of processed sound signal stable and close to zero. This is, however, a strong limitation for other use, for example for DC measurements.
The situation, fortunately, is not so bad as it seems...
Results of SB analysis
Analyzed, with a good magnifying glass and ohmmeter, LINE IN inputs of four different sound cards - three from Creative Labs, one from Manli:
- SB16 (PCI), model CT4810(?),
- AWE-64 (IDE), model 4520,
- Audio PCI 5000 (PCI), with chip ES1371,
- Manli CMI8738SX (PCI)
Inputs of SB16, Audio PCI5000, AWE-64 and CMI8738SX, respectively, are on the Fig. 1.
Fig. 1: SB16, Audio PCI5000, AWE-64 and CMI8738SX LINE IN inputs.
As it can be seen, three inputs are very simple. Input of AWE-64 is a bit more complicated. It contains standard FET operating amplifier, but not condenser at the input. The condenser is at the output, however...
All four sound cards have DC default level at mixer input significantly high. The values displayed don't reflect reality. It was found, that it is close to 2.5V. Direct connection of external DC is not applicable. Is there a solution?
Possibility of DC input solution
There exists well known application of operating amplifier - differential amplifier. It's schematics (Fig. 2) is quite simple.
Fig. 2: Differential amplifier.
A brief inspection of Fig. 1 shows, that AWE-64 already has operational amplifier. Good new! It is candidate No. 1. Assumed changes will be negligible.
Result
What is needed:
- disconnect noninverting input from ground,
- make tunable source of U1, one for both channels should be enough,
- with a piece of wire make a shortage between condenser pins,
- with running PC tune U1 to get appropriate DC level.
The resulting schematic is on Fig. 3.
Fig. 3: AWE-64 input modification.
With operational amplifier on small PCB, SB16 and CMI8738SX were also checked . The final version had been made with CMI8738SX Manli sound card. Only reason for selection was that it was cheapest and is currently available. Additional to Fig. 3 the schematics contais -5V chip, as sound card has none.
The rest are a bit older models. The results of all sound cards were comparable.
The solution is not limited to AWE-64 and comparables. It seems any sound card can be modified provided small PCB with operational amplifier will be added. At the begining AWE-64 was chosen only due to fact it already has the (pre)amplifier. However for the final solution it was not suitable - in between mother board of home computer changed and ISA slot gone...
The final solution
To test, and even to use the device, one need some useful program. As a first choice Konstantin Zeldovich's Winscope was decided. It is complete, sophisticated and free. However, its use for more serious job is not very easy as it doesn't contain calibration feature and, what's most important, it doesn't allow AC/DC V/A measurements with numeric output.To meet our needs we developed original program. It is two channel:
- oscilloscope,
- AC/DC V/A meter,
- frequency meter,
- VU-meter
Hardware
The device with manual range switch was equipped to make it a real osciloscope. Its construction is very simple:
Fig. 4: Manual range switch (one channel only).
No special components were used. Dual switch was constructed in small metal box with input bushings. It is connected with LINE IN input by standard shielded stereo cable. Switch takes very little space at the table, PC sits near the table, so no change in the organization in the room was needed.
Software (Can be used in 95 to Win7 )
It was created program to use all information available. It is quite complex one. As it can be seen from Fig. 5, it is dual beam oscilloscope-like device combined with AC/DC multimeter and frequency meter.
Fig. 5: Soundscope main screen.
Soundscope screen has the following parts:
- scope window
- channel controls panel
- multimeter & controls panel
The scope window has:
- width 11.6 ms or 92.9 ms depending on sweep range selection (see below),
- height +/- 3 depending on range switch selection (see below),
Single click on scope window activates image save dialog - it allows to save screen shots. Currently supported are BMP, GIF and JPG formats.
Below the scope window there is status bar displaying (sometimes) status messages.
Panel of channel controls on the right side of the scope window contains 2 identical sets of controls for each channel - A and B - (from left to right):
- zero level
- gain
- trigger level (below gain control)
Multimeter & controls panel contains (from top to bottom):
- multimeters
- sound device selector
- trigger control
- time base control
- operation controlls
Multimeter window contains two displays - larger and smaller ones - larger one displays voltage/current or raw data depending of calibration/raw data button status. Smaller one displays frequency in Hz.
At the right side there are range switch buttons. They are active only if soundscope is calibrated.
AC measurement is enabled by "Hz" button. When pressed, both windows - multimeter and frequency - display AC values.
Below those multimeters there is sound device selector.
The trigger control group consists of (from top to bottom):
- triggering enable/disable
- channel A or B selection
- indicator of active triggering (yellow=active)
Time base control contains 2 butons in group:
- fast - 1 ms/div
- slow - 10 ms/div
Data saving definition button opens small window for data saving options:
Fig. 6: Data saving definition screen.
Right lower corner contains by control buttons:
- calibrated/raw display button
- start/stop button
- hold/release button
- start/stop data saving button
- about
- help
- program close
Description
Program was created using Borland Delphi 6. No shareware or commercial libraries or components were used. To control mixer it was used excellent free mixer component developed by Vit Kovalcik.
All copyrights of the program are owned by the authors. The noncomercial use of the program is free of any charge. All other use must be consulted with the authors.
Program is based on LINE IN inputs use. It is set to use two-channel 16-bit A/D conversion at 44.1 kHz sampling frequency.
Buffer size of the input sampling is 4096 samples, e. g. measurement frequency is 10.7 measurement per second.
Due to low sound card sampling frequency the highest frequency of the acceptable processed signal is around 10kHz. Higher frequencies are processed too, but the AC accuracy drops down.
Anyway DC measurements can be quite accurate, depending on calibration accuracy, of course and sound device A/D converter quuality.
The main domain of the device use should be, except of use as standard multimeter, DC and low frequency AC measurements.
AC amplitude measurements are achieved by software rectifying - the value displayed is close to effective value of the AC signal.
Frequency measurement is achieved by periods count measurement. As the measurement is sampled by 1/44 100 s, it is also measure of the frequency display accuracy. The smallest measurable frequency is around 20Hz.
Triggering is derived from channel A or B. There is no possibility to have triggered both channels. Triggering level can be set. Trigger level is not dependent on display zero level. Currently only positive levels can be set.
As the signal is sampled, e. g. not continual, the resulting triggered display is usually not fully stable.
Successful use of the program expects proper sound card setup. It is accessible via MS Windows Control panel -> Sounds and Multimedia -> Audio -> Recording setup. For more details check Microsoft Windows help.
An example of sound recording setup parameters.
Hardware modification described in this article, provided properly set, does not influence sound card standard features in any way. The modified card can be still used the standard way.
Calibration
Since the soundscope can be used as no calibrated, it's not its goal. To use multimeter functions it is necessary to calibrate all ranges.
Before calibration is started, it is suggested to measure linearity and sensitivity of the LINE IN input. It can be easily done using voltage calibration circuit described below.
To calibrate soundscope properly it is needed to prepare:
- variable voltage/current source 1 to 15V DC/1A,
- good potentiometer,
- good multimeter, preferably digital one,
- manual range switch properly set and connected with LINE IN input of sound card.
Calibration is three steps process. It consists zero level calibration, sensitivity measurement and measurement ranges calibration, which consists of three identical steps to calibrate voltage ranges and one step to calibrate current range (if used).
First step is zero level calibration. It requires disconnect any external voltages from inputs and connecting both ones with ground. Soundscope is switched to Raw data mode. Average value is read for each channel and written into program INI file.
Second step is sensitivity calibration. It requires connecting potentiometer with external DC voltage to both inputs. Soundscope is switched to "Raw data" mode. Potentiometer is set to minimum and slowly turning to get signal as close as possible to red line above (or belove) zero line. Voltage required and average raw value is read for each channel and written into program INI file. There is only one value for both channels. They should not differ in sensitivity, however.
To calibrate voltage ranges one is expected to use circuit according Fig.7. Use of regulated power source is very convenient, anyway the calibration can be sufficiently done using batteries as power source. In this case small lamp should be used to limit current.
Current range is calibrated with the help of circuit on Fig. 8. It should be noted, that ground bushing is not used. This is possible only if the power source has ground insulated from common ground. If it is not available, battery with lamp should be used.
Fig. 7: Voltage calibration circuit.
Fig. 8: Current calibration circuit.
- select measurement range on range selector (the same in both channels)
- set corresponding range on manual range switch
- bring externam voltage/current to inputs
- set voltage/current level to be exactly identical with range switch value
- read voltage/current values displayed on both displays
- calculate CalFactorR, CalFactorL values and write them to INI file
Example:
DC input: 0.2V
Display A: 0.192V
Display B: 0.211V
CalFactorR = 0.2/0.192 = 1.0416666667
CalFactorL = 0.2/0.211 = 0,9478672986
Program INI file
Program doesn't write anything to the MS Windows registry anymore. All required information is now stored in the INI file. It is standard ASCII text file. To change values in the INI file it is expected to use ASCII editor, Windows Notepad is good enough. Use of Winword may produce non-ASCII file and program will crash.
Program INI file name is soundscope.ini and it resides in the same directory as program file. It has following structure:
| [Program] | |
| Debug = 0 | If set to "1" it activates program log creation |
| XPlook = 0 | for "classical" Windows theme use "0", for parrot-like XP theme use "1" |
| [Devices] | |
| Device Name = C-Media USB Headphone Set | Selection of sound device to use, if not found, first one available will be used instead. |
| LineIn Name = Microphone | Exact name of input channel to use. Can be found in Control panel - Sounds and Audio Devices settings. It is very important to set correctly, othervise program will not work |
| [Calibration] | |
| Zero left = 0 Zero right = 0 | Raw average values of each channel |
| MaxLevel = 12480 | |
| MaxVoltage = 0,117 | |
| [Range1]..[Range4] | |
| LabelL = 0.2V, LabelR = 0.2V | Range for channel A and B respectively. It is both label for range switch and internal calculations parameter. |
| CalFactorR = 1 CalFactorL = 1 | Correction callibration factors. Before calibration is dome it is "1", after calibration it changes. Never set "0", othervise program will crash. |
| [Capture] | This section contains parameters written by program alone. Don't change any of them. |
| NameOfFile =captured.csv | |
| SamplingType = CSV | |
| CaptureTime =60 | |
| SamplingPeriod =1 | |
| TimeMeasure = min | |
| [Visible] | This section contains labels used for display. Translation to other language will translate user interface. |
Notes for construction
There are no special components used, except 11M resistor in switch. However silicon diodes at the input should be fast ones and should have very high resistivity. 1k resistor conducting signal to them and LINE IN should be as small as possible - its function is to be fuse. It should burn to prevent the input from overloading. Diodes should bear the "burning" current, of course.For soldering at the sound card microsolder is needed. Transformer solder must be avoided. A good lens or glasses and a certainty in hand may be needed too...
Be careful when disconnecting input pins from ground (provided sound card has preamplifier already). SMD chips are quite fragile!
Small pieces were glued of universal PCB carrying additional components close to the LINE IN input. All joins we did with insulated thin copper wires.
The overall view of the experimental prototype can be seen on Fig. 9.
Fig. 9: Prototype view.
Features summary
| sampling frequency | 44.100 Hz |
| measuring frequency | approx. 10.7/s |
| measuring ranges | 0.3, 3, 30V and 3A |
| accuracy | better than 1%*) |
| type of measurement | AC and DC |
| maximum input frequency | 22kHz |
| working input frequency range | 20Hz - 10kHz |
| input resistance on voltage ranges | 333kOhm/V (100k, 1.1M, 12.1M) |
| input resistance on current range | 0.1Ohm |
| data saving file format | WAV or CSV |
| sampling times | continual, 1/4, 1/2, 1, 15s, 1, 5, 15, 60min |
| saving time range | 1s - 9999min**) |
**) 1s captured WAV file has size 176kB, 1 hour captured WAV file has size 635MB!!, an attempt to capture 9999min WAV file will fill your hard drive for sure...
3 comments:
Amazing Post Rushi..Cant we use graphics card using HDMI port?
Thanks for the great post
where to download soundscope and multi meter software ? thanks
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