Osciloskope

[dbanner]

Use Zeitnitz oscilloscope software, It is free. A bonus is that it displays the freq. of waveform so you know if TX oscillator is bang on. Also by connecting Rx coil to TX oscillator, you can work out if your Rx inductance is within spec. This is what i used on my second tgsl build for calibration and it displayed nice waveforms, only bad thing is that it does not display accurate ampilitude. And it has two channels, so you can show waveforms side by side. Here is a tip: you can squeeze in or expand your TX coil a little to get freq. you want.

[BKY1337]

Ok, thanks. I will try it tomorrow.
But i think i will get this spikes again.

[Davor]

No, but the best way to connect a coil to a scope is by connecting a scope to Rx front end amplifier output. That way coil sees proper termination, and scope sees low impedance source, which is a big bonus when scoping with a sound card.

[BKY1337]

Im interested in a picture of your soundcard oscilloscope when a coil is connected.
Do you have one? Or can you tell me how it looked like?

Mine looked like spikes because of the poor resolution.

[Davor]

No I don't, but it works as is.

[mohandes]

thanks Davor
ok i download now and run it to test it.
i need the lincense kode?do you have

[Davor]

Ah! In case you wanted to use any of these to do any measurements a PI front end, just forget about it - too slow.

[Davor]

So far the easiest to use that I'm aware of is found here: http://www.zeitnitz.de/Christian/scope_en
It has some off licensing, but it works fine.
The above mentioned Visual Analyser works fine as well but it is a bit confusing.
Results will depend upon your soundcard quality, and you can not expect super accuracy even after you calibrate these, but for the relative measurements both will be just fine.

[mohandes]

hi davor
an you put for me the oscilloscope software for the computers,i have Cool Edit Pro 2.1 but it dosent good.
thanks

[Davor]

Protection diodes are not needed if you power your rig with batteries. You simply can't produce voltages nearly high to do any damage. That is actually the only caveat. Real laboratory instruments have carefully designed power supplies that float. You can't expect a piece of consumer electronics such as PC to be as good, so make sure your device under test is floating instead - power it with batteries.

You can put antiparallel diodes in parallel with a 470ohm resistor if it makes you feel better.

To do any meaningful measurements in ~10mV range, you'll have to connect your PC sound card directly. In that case make sure you actually have a low impedance to hook it to, and that you do not expect much more than 100mV there. The best example is hooking the PC to a 1k resistor at the output of a preamp in order to fine tune the coil balance. First you establish a coarse minimum to get below 100mV using a 1:10 probe, and only then you hook it directly, and with no 470ohm resistor. See example:

[labtec1]

I think it's best to insert an old sound card in the PC costing 1e around anyway, so what is one to be - there will be a shame if something goes wrong

[6666]

Hi Davor
thanks , it has no protection diodes, are they not needed for sound card ?

[Davor]

Something like this...

[6666]

Davor
what are you useing as a probe for the sound card ?
thanks

[labtec1]

thanks for answers
ebaj to have very interesting things but I'm from Serbia and I wonder if you'd say buy a $ 50 oscilloscope how much it would cost in Serbia and how they are delivered