# About a Diy pc oscilloscope found on the Net

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#### Gaetan Mailloux

Jan 1, 1970
0
Hello

I've found this pc oscilloscope web page;

Any one try this ADC for pc scope ?

Is there any freeware to do spectrum analysing (FFT) who would work with
that PC parallel port ADC ?

Thank

S

Jan 1, 1970
0
Is there any freeware to do spectrum analysing (FFT) who would work with
that PC parallel port ADC ?

If you can save the wave with their software, you can do FFT with
www.dplot.com trial version is free, something like $35 to own it! I recommend it highly, I've been using it for years! S #### scada Jan 1, 1970 0 scada said: If you can save the wave with their software, you can do FFT with www.dplot.com trial version is free, something like$35 to own it! I
recommend it highly, I've been using it for years!
At a second look at that circuit, the A/D chip has only 8 bit resolution.
That's not going to give you much of an FFT!

G

#### Gaetan Mailloux

Jan 1, 1970
0
At a second look at that circuit, the A/D chip has only 8 bit resolution.
That's not going to give you much of an FFT!

Hello

How much bit are need to do FFT ?

Thank

Gaetan

S

Jan 1, 1970
0
Gaetan Mailloux said:
Hello

How much bit are need to do FFT ?

Thank

Gaetan

The Nyquest theory states you want to sample at a rate of at least twice the
highest frequency you want to see.

G

#### Gaetan Mailloux

Jan 1, 1970
0
The Nyquest theory states you want to sample at a rate of at least twice the
highest frequency you want to see.

Hi

Here's what they said at the scope web site;
http://scopeonpc.tripod.com/index.htm

Key Features

Sampling Rate 100K Samples per second
-5 V To +5V Input Range
8 Bit Resolution
Scope Timebases:100uS/Div To 100mS/Div
Scope Volts/Div: 100mV/Div To 5V/Div
Works with ANY parallel port

Thank

Gaetan

J

#### jcomeau_ictx

Jan 1, 1970
0
Here's what they said at the scope web site;http://scopeonpc.tripod.com/index.htm
Key Features
Sampling Rate 100K Samples per second
-5 V To +5V Input Range
8 Bit Resolution
Scope Timebases:100uS/Div To 100mS/Div
Scope Volts/Div: 100mV/Div To 5V/Div
Works with ANY parallel port

So, a 50 KHz Nyquist frequency. A little better than twice what you
get from the input port of your sound card, at much lower resolution
(16 bits is 256 times the resolution of 8 bits, and 16 bit sound cards
are commonplace). In Canada, as in the US, you ought to be able to
find analog oscilloscopes for $50 or less at yard sales or eBay; that might be a better use of your money. I've used the input port of a sound card as a low-frequency digital scope. It worked, for example, to see the encoding on the magstripe of a credit card, by hooking up the read-head of an old tape player to the microphone port of my computer and dragging the card across it. This was years ago, and I had to write my own software. Nowadays you have freeware like Audacity that will do that part for you. G #### Gaetan Mailloux Jan 1, 1970 0 jcomeau_ictx ([email protected]) said: So, a 50 KHz Nyquist frequency. A little better than twice what you get from the input port of your sound card, at much lower resolution (16 bits is 256 times the resolution of 8 bits, and 16 bit sound cards are commonplace). In Canada, as in the US, you ought to be able to find analog oscilloscopes for$50 or less at yard sales or eBay; that
might be a better use of your money.

I've used the input port of a sound card as a low-frequency digital
scope. It worked, for example, to see the encoding on the magstripe of
a credit card, by hooking up the read-head of an old tape player to
the microphone port of my computer and dragging the card across it.
This was years ago, and I had to write my own software. Nowadays you
have freeware like Audacity that will do that part for you.

Hello

I mostly want to do spectrum analysing of distortion, I have a sine wave
oscillator who have less than .0003 % distortions. Most soundcard do
have quite high distortion to do that with a software, and buying a spectrum
analyser adaptor for an oscilloscope cost quite to much for me.

Thank

Gaetan

J

#### John Bordynuik

Jan 1, 1970
0
John Bordynuik cut and paste " I mostly want to do spectrum analysing of
distortion"

Hello Gaetan,

interface or differential, then capture the data on the PC using an
inexpensive (but fast) PCI DIO card. This solution would cost you less than

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