About a Diy pc oscilloscope found on the Net

[Gaetan Mailloux]

Hello

I've found this pc oscilloscope web page;

http://scopeonpc.tripod.com/adc.htm

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

Gaetan, Canada

 

[scada]

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!

 

[scada]

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!

 

[Gaetan Mailloux]

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

 

[scada]

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.

 

[Gaetan Mailloux]

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
-50V To +50V Olerload Protection
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

 

[jcomeau_ictx]

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
-50V To +50V Olerload Protection
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.

 

[Gaetan Mailloux]

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

 

[John Bordynuik]

John Bordynuik cut and paste " I mostly want to do spectrum analysing of
distortion"

Hello Gaetan,

Consider using fast ADCs (>20 Mhz ADS1610 or something), parallel
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
$600.00 if you built it yourself.

I just finished a 128-channel unit.

Regards,

John Bordynuik
CPU Architect
JBI

 

[Jean-Yves]

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.

I'm afraid you wont be able to detect such distortion with equipment
that is less than $20000....