How can I see the headphone output signal from my PDA (Palm Tungsten T3) on my
HPS 140? Both are battery operated instruments and not grounded.
Peter
Get a suitable jack (e.g. 3.5mm stereo or similar).
Connect probe ground clip to gnd of jack, connect probe tip to L or R of jack.
Please Google for jack pinout.
[quote=“VEL417”]Get a suitable jack (e.g. 3.5mm stereo or similar).
Connect probe ground clip to gnd of jack, connect probe tip to L or R of jack.
Please Google for jack pinout.[/quote]
That is exactly what I have done, groundclip to gnd of jack (also to earth), but it doesn’t work.
I have a tone generator in the Palm and I can hear the sine wave (1000Hz) on my headphone. But the signal on the HPS140 is instable (floating?) and by no means a sine wave.
Is your HPS140 working correctly with a different signal source?
Is the probe OK?
Are you sure the ground is connected correctly?
If auto setup is not working correctly, try AC coupling and manual time/div setting.
The HPS140 is new and the Ac current from a 24V adapter is clear on the screen, also the square testsignal from the scope itself.
Manual settings doesn’t make it better. It remains a very instable and vibrating signal instead of nice clear sine.
Thanks for your support till now.
Peter
Please try with an identical signal from a different source.
If the problem persists, return scope for inspection/repair.
Make sure to include a copy of this conversation.
To avoid transport & handling, return scope to your Velleman distributor.
The HPS140 is new and the Ac current from a 24V adapter is clear on the screen, also the square testsignal from the scope itself.
Manual settings doesn’t make it better. It remains a very instable and vibrating signal instead of nice clear sine.
Thanks for your support till now.
Peter[/quote]
Can you get a screenshot of what you are seeing?
An app on a PDA is not necessarily a lab grade source, so it could be that its signal contains sampling frequency artifacts that are messing with the scope’s triggering. I have seen many consumer level digital audio devices with very high levels of 44kHz, 48kHz, etc. artifacts that are expected to be filtered out by something downstream, headphone response typically falls off very fast after 16-17kHz and effectively masks these sampling artifacts and other higher frequency content.
The HPS140 is new and the Ac current from a 24V adapter is clear on the screen, also the square testsignal from the scope itself.
Manual settings doesn’t make it better. It remains a very instable and vibrating signal instead of nice clear sine.
Thanks for your support till now.
Peter[/quote]
Can you get a screenshot of what your are seeing?
An app on a PDA is not necessarily a lab grade source, so it could be that its signal contains sampling frequency artifacts that are messing with the scope’s triggering. I have seen many consumer level digital audio devices with very high levels of 44kHz, 48kHz, etc. artifacts that are expected to be filtered out by something downstream, headphone response typically falls off very fast after 16-17kHz and effectively masks these sampling artifacts and other higher frequency content.[/quote]
The HPS140 is new and the Ac current from a 24V adapter is clear on the screen, also the square testsignal from the scope itself.
Manual settings doesn’t make it better. It remains a very instable and vibrating signal instead of nice clear sine.
Thanks for your support till now.
Peter[/quote]
Can you get a screenshot of what your are seeing?
An app on a PDA is not necessarily a lab grade source, so it could be that its signal contains sampling frequency artifacts that are messing with the scope’s triggering. I have seen many consumer level digital audio devices with very high levels of 44kHz, 48kHz, etc. artifacts that are expected to be filtered out by something downstream, headphone response typically falls off very fast after 16-17kHz and effectively masks these sampling artifacts and other higher frequency content.[/quote]
You are perfectly right.
I have tested the HPS140 with a function generator and the scope is working great.
I have also tested the Palm headphone signal with another (analog) oscilloscope and then you see a very bad (low frequency) signal with many high frequency components, all very instable.