INS TECHNOLOGY reserves the right to make modifications to this manual at any time without notice.
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1 VIRTINS
®
Sound Card Oscilloscope Probe (P601) Manual
Virtins Technology
Table of Content




1 Introduction .................................................................................................................. 3
1.1 Probe kit for VIRTINS Multi-Instrument series (1 channel, part number
P601PC) ....................................................................................................................... 3
1.2 Probe kit for VIRTINS Pocket Multi-Instrument series (1 channel, part number
P601PPC) ..................................................................................................................... 4
2 Specification ................................................................................................................. 4
3 Safety Instructions ........................................................................................................ 5
4 Equivalent Circuit......................................................................................................... 5
5 Detailed Calibration Procedure for VIRTINS Multi-Instrument ................................. 6
5.1 Main Step 1 --- Initial State Check: ....................................................................... 6
5.2 Main Step 2 --- Ground Level Correction (Zeroing): .......................................... 10
5.3 Main Step 3 --- Calibration of Attenuation Factors for Probe Switch Positions 1, 2,
3.................................................................................................................................. 11
5.4 Main Step 4 --- Calibration of Sound Card Input Channel .................................. 13
5.5 Main Step 5 --- Calibration of Sound Card Output Channel................................ 13
6 Detailed Calibration Procedure for VIRTINS Pocket Multi-Instrument.................... 14
7 Warranty ..................................................................................................................... 15
8 Disclaimer................................................................................................................... 15


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2 VIRTINS
®
Sound Card Oscilloscope Probe (P601) Manual
Virtins Technology
1 Introduction

VIRTINS Sound Card Oscilloscope Probe (Model No. P601) is the worlds first sound
card based oscilloscope probe. It has an ordinary oscilloscope tip and ground lead at its
front end, and a RCA plug (male) at its back end. It can be connected directly to a sound
card with RCA input jacks (female), or connected to an ordinary sound card via a stereo-
to-2RCA converter or a mono-to-1RCA converter. P601 has a 3-position switch which
allows you to choose different attenuation settings. It has an input protection circuit
which prevents the sound card and the computer from being damaged by accidental high
input voltage within
±24 V. With this probe, the measurement range of a sound card
oscilloscope is broaden to from as low as 1 µV to up to 24 V.

P601 can also be used as the output leads for Sound Card Signal Generator. To reduce the
output impedance, it is recommended to put the attenuation switch to Position 1.

There are two kits available at Virtins Technology.

1.1

Probe kit for VIRTINS Multi-Instrument series (1 channel, part
number P601PC)

It contains: 1 Probe, 1 Stereo-to-2RCA converter, 1 Mono-to-1RCA converter and
accessories.


Fig. 1 P601PC

You may need from 1~4 sets of this probe kit per license of the software, depending
on your purpose of test. We recommend the standard configuration be 2 sets per
license.
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3 VIRTINS
®
Sound Card Oscilloscope Probe (P601) Manual
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1.2

Probe kit for VIRTINS Pocket Multi-Instrument series (1 channel,
part number P601PPC)

It contains: 1 Probe, 1 HeadsetJack-to-3RCA converter and accessories.


Fig. 2 P601PPC

You may need 1 set of this probe kit and 1~2 sets of the probe kit for VIRTINS
Multi-Instrument series. We recommend the standard configuration be 1 set of this
probe kit (P601PPC) and 1 set of the probe kit for VIRTINS Multi-Instrument series
(P601PC).

2 Specification

Maximum Allowable Input Voltage:
±
24 V

Built-in input protection circuit ensures its output to be less than 3V at all time,
provided the input voltage is within the allowable range
Three switchable attenuation positions: 1, 2, 3, with input impedance equal to
1 k + sound card input impedance, 201 k + sound card input impedance,
10.001 M + sound card input impedance respectively. Note that the sound
card input impedance, either MIC IN or Line In, is card dependent and ranges
from 600 to 50 k.
Frequency range: 0~200 kHz
Soft molded strain reliefs at all stress points assure long cable life.
Accessories include sprung hook, 6" ground lead.
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4 VIRTINS
®
Sound Card Oscilloscope Probe (P601) Manual
Virtins Technology
Its back end is a RCA plug (male) and can be connected to an ordinary sound
card through a stereo-to-2RCA converter or a mono-to-1RCA converter. No
converter is required for those sound cards that have RCA jacks for input and
output.
Can be used in Signal Generator for signal output. The output impedance is
about 1 k, 201 k and 10.001 M for attenuation switch Positions 1, 2, 3,
respectively.
3 Safety Instructions

!
Always keep in mind that the input of the probe is NOT galvanically isolated
from the sound card connected.
Never connect to a signal with unknown amplitude.
Never connect to a signal with voltage greater than 24V.
If you are not very sure about the exact voltage under test, always start
measurement by putting the attenuation switch to Position 3 which has the
highest input impedance.
Never plug in or plug out the probe from the sound card when the probe is
already connected to powered external device.
Be extremely careful when the voltage under test is greater than 5V.
It should be noted that for many sound cards (typically the internal sound card
of a desktop PC or a laptop PC with a built-in AC power supply adapter), the
ground line of input and output is connected to mains earth. This is not a
problem if the circuit under test is floating (i.e. isolated from earth). Otherwise,
you MUST make sure that the ground lead of the probe is connected to a point
on the circuit that is also at earth potential.


4 Equivalent Circuit

When the built-in input protection circuit of the probe is in inactive state, the probe
impedance, Zprobe, and the sound card input impedance, Zsc, form a voltage divider as
follows:




Zprobe
Zsc
Ui
Uo





Fig. 3 Probe Equivalent Circuit

The ratio between the output voltage Uo and input voltage Ui is thus:

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5 VIRTINS
®
Sound Card Oscilloscope Probe (P601) Manual
Virtins Technology
Uo/Ui=Zsc/(Zprobe+Zsc)

where Zprobe = 1 k, 201 k, 10.001 M respectively for probe switch Positions 1, 2, 3,
and Zsc is in the range of 600 ~ 50 k, depending on the sound card and channels
(MIC In or Line In) used.

The built-in input protection circuit of the probe becomes active when the input voltage
causes the output of the probe exceed 3V. When it is in active state, it clamps the voltage
at 3V to ensure that no excess voltage is applied to the sound card. This protection works
only if the input voltage is within the maximum allowable voltage.

When voltage clipping happens (you can see flat top or flat bottom if the input is a
sine wave), you should put the probe switch to a position with higher attenuation factor
until no voltage clipping occurs.

5 Detailed Calibration Procedure for VIRTINS Multi-
Instrument

There are many ways to calibrate VIRTINS Multi-Instrument. The simplest ways is to
use a multimeter. The following procedure assumes that you have purchased two
VIRTINS Sound Card Oscilloscope Probe (P601) and has an ordinary multimeter with
you.


5.1 Main Step 1 --- Initial State Check:

Step 1:
Open Recording Control panel for the sound card to be calibrated under Windows
Control Panel (see Fig. 4), and select Microphone or Line In depending on which
one you want to calibrate with. And then, put its slider to maximum.


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®
Sound Card Oscilloscope Probe (P601) Manual
Virtins Technology


Fig. 4 Recording Control under Windows Control Panel

If the s