PC based oscilloscope

[multieagle]

As usual I do not fully comprehend what is being discussed. Will probably work up to an understand, say in the next twenty years! Can a probe be made that plugs into the mic input? Or must it be connected directly to the sound card? What about a high end microphone to measure frequency, and perhaps other measurements? Thanks for being patient. Whew! wonder what it is gonna be like when I actually tackle putting the Surf PI kit together?

[multieagle]

Will this work: http://www.ebay.ca/itm/BRAND-NEW-HP-...item4399c34dba

[multieagle]

Ignore that last post . . . How embarrassing!

[mohandes]

hi all
i make probe like the picture?dose it work well?

[kabier]

hi mohandes try it and let us know. post your result and measurements
thanks and regards

[6666]

This is how I made my simple probe
I have a real CRO probe going to a diecast box
in the box is a small piece of scap pcb
on which I soldered a 1/4 Watt 47K resistor
a 100volt Cap and two 1n4148 diodes.

Then shielded cable to a plug which is plugged into the sound card.

I made it this way so i could unplug the real CRO probe and plug it into
my CRO for comparison,

You can make it from a couple of clips and shielded cable, coax and just solder it together.

The original ratings of the components were higher than necessary.

[6666]

What is the difference between:
2 Channel PC Computer Digital Storage USB Oscilloscope




&

5 Channel PC Computer Digital Storage USB Oscilloscope


Each one probably contains some IC's
one to give 2 channels and the other to give 5 channels.
There is a difference in frequency and sampling range, etc.
5 Channels would give you more wave forms to look at
and it can record.

[6666]

Will this work: http://www.ebay.ca/itm/BRAND-NEW-HP-...item4399c34dba

That would work ok to get the sound into your laptop
when I first looked at this project I bought a USB sound card
to try first in case I blew up the soundcard in my PC,
but have not installed it, because the probe and soundcard in my PC works ok
for this project.

[6666]

mohandes
I would add some protection diodes between tip and ground and ring and ground just to be safe.

[mohandes]

HI 6666
i will make the prob at number 10, is it work?tell me that make it
ok i put 2 picture for ne555,for pin 3.i think not well what do you think?

[kabier]

hi all using diodes look like abridge rectifier and i think will deform the measured wave
i just finished soldering a probe without diodes will test it and post
thanks

[Davor]

With the most PC sound cards it will be fine as they are capable of handling a bit extra. Make sure that a device under test is powered by batteries when you take measurements, and a good precaution is listening to the sound off the PC.

The battery part is essential. You must have a single common ground. As PCs are not built with much of a power supply, a PCs ground will have to do, but in that case it is very important to power your device with batteries.

Diodes are just simple clamps that protect the sound card input if the signal becomes too big. They'll start conducting at about 0.5V. I didn't use them.

Now that I have a ye olde CRO sillyscope I can connect it as ever I wish, but only because old oscilloscopes were built to effectively isolate a scope from the mains, even at high voltages of ye olde CRT TVs.

Use batteries and you'll be fine.

[multieagle]

I'm going to give this a try: http://www.tigerdirect.ca/applicatio...erReviewsBlock

A little more expensive, but at least in country.
StarTech.com ICUSBAUDIO7 Virtual 7.1 USB Stereo Audio Adapter External Sound Card - USB 2.0, USB 1.1, Phono 3.5mm Female, C-Media Chipset

[Davor]

IMHO this is the best deal around: http://www.tigerdirect.ca/applicatio...891&CatId=2769
...provided you have a PCI slot available.

[multieagle]

Okay, I'm going with the usb sound card adapter. I'm looking at a sound card oscilloscope probe with the following specs:


Probe Specification

• Maximum Allowable Input Voltage: ± 24 V
• Built-in input protection circuit ensures its output to be less than 3V at all time to pretect the sound card from being damaged by excess input voltage, provided the input voltage is within the allowable range
• Three switchable attenuation positions: 1, 2, 3, with input impedance equal to 1kΩ+sound card input impedance, 201kΩ+sound card input impedance, 10.001MΩ+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 Ω to 50 kΩ.
• Frequency range: 0~200 kHz
• Soft molded strain reliefs at all stress points assure long cable life.
• Accessories include sprung hook, 6" ground lead, marker bands.
• 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 kΩ, 201 kΩ and 10.001 MΩ for attenuation switch Positions 1, 2, 3, respectively.
• Note: The probe is NOT gavanically isolated from the sound card connected.

Would this be sufficient for purposes of testing a PI detector and coil?

Thank you.