VM167 Kit and AC signal

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1

Hello,

I’m working on a project and i use the usb VM167 kit to get some Ac singal information. I have some probleme with it. if i connect a speaker to the analogic input i get some value but not good to work with it. Is it possible to use this kind of kit to get the AC signal of a speaker ( or photodiode…) ?

Thanks for helping me.

Best Regards

2

[quote]Is it possible to use this kind of kit to get the AC signal of a speaker [/quote]This kit can not accept AC signal. Only positive DC voltage is accepted as the input signal. The command execution time for read is 4ms, so only low frequency (DC) signals can be recorded.

3

Thanks for your reply.

Please can you tell me if velleman have made a product to record AC Signal (4 input ac Signal at the same time) ?

Thanks for you answer.

Best regards

4

[quote]Please can you tell me if velleman have made a product to record AC Signal (4 input ac Signal at the same time) ?[/quote]At the moment there is no such product in the Velleman product line.
Oscilloscopes (e.g. PCSU200) can record two AC signals at the same time.

5

I’m curious - is this a Windows (OS and/or DLL) limitation? Or maybe it depends on USB version used? I was a bit concerned when I saw it in the specs, since I thought I might want to do somewhat faster sampling, but when I try reads in a tight loop on a modern PC running FreeBSD, using the C port of the DLL by member rahlskog (uses libusb), I consistently see ~ 250 microseconds for ReadAllDigital() and ReadAnalogChannel(), ~ 360 microseconds for ReadAllAnalog(). Granted, that still limits you to ~ 2 kHz AC for a single channel (and of course you need to bias it to all-positive), but it’s more than an order of magnitude better than the specs say…