My students and I are having a project trying to explore WaveForms with USB soundcard to it's maximum. We designed a simple OPAMP adapter and removed the blocking capacitor with the polarizing resistor at the microphone input. We expected to see the complete signal (DC+AC) on the oscilloscope, but the latest USB sound cards we obtained did not pass the DC voltage. An older sound card I had from 3-4 years ago did not block the DC signal.
Can you help us with this issue?
The old card reported to the "lsusb" command as: 0d8c:000e C-Media Electronics, Inc. Audio Adapter (Planet UP-100, Genius G-Talk Cmedia), while the new ones as: 8086:0808 Intel Corp.
Thank you,
J.Kjosev
P.S. Regarding the triggering - we intend to add short high-amplitude pulses to the input signal at certain level of the output (eg. at zero crossing) and trigger the oscilloscope at this (much higher) level than the observed signal :)
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josif
Hallo Atilla,
My students and I are having a project trying to explore WaveForms with USB soundcard to it's maximum. We designed a simple OPAMP adapter and removed the blocking capacitor with the polarizing resistor at the microphone input. We expected to see the complete signal (DC+AC) on the oscilloscope, but the latest USB sound cards we obtained did not pass the DC voltage. An older sound card I had from 3-4 years ago did not block the DC signal.
Can you help us with this issue?
The old card reported to the "lsusb" command as: 0d8c:000e C-Media Electronics, Inc. Audio Adapter (Planet UP-100, Genius G-Talk Cmedia), while the new ones as: 8086:0808 Intel Corp.
Thank you,
J.Kjosev
P.S. Regarding the triggering - we intend to add short high-amplitude pulses to the input signal at certain level of the output (eg. at zero crossing) and trigger the oscilloscope at this (much higher) level than the observed signal :)
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