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Noisy Signal from USB 6211

Hello All, 

I'm very new here and need help.

I just got new USB 6211 and used to get signal from lock-in amplifier.

The signal seems to be very strange. To check it, I applied only 5v from the lock-in and the signal is so weird. See the attached file.

it suppose to be 5v output, but as you can see it is noisy at some interval, goes to zero at other intervals, and solid 5v sometimes in a repeatable systematic way!

Can you please guide me through this.

thanks

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Message 1 of 11
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Does the lock-in amplifier take some time to 'lock in', and then after a period of stability, reset so that it can get a new measurement? It's my guess that's what's happening for you.

 

If you provide some information about the amplifier (model number, or preferably a link to/upload of the manual) then we could look closer.


GCentral
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Hello,

the lock-in is the standard one from Stanford research ( SR830 )

however, I believe it is not lock-in issue. Cus i got similar response with 2v battery 

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Sorry - to confirm: you connected a 2V battery to the 6211 (presumably as an analog input) and the behavior was similar? At what sampling rate - I note the graph you posted a picture of shows THz sampling and the 6211 only supports up to 125kHz. The SR830 only claims to be able to reach around 100kHz and has outputs to Serial and GPIB.

 

What are you connecting to what, and where did the THz graph come from (or is the scale just completely wrong?) I'm pretty confused...

 

Edit: I see this in the manual for a possible analog input to 6211:

AUX OUT 1-4 (D/A Outputs) These are auxiliary analog outputs. The range is -10.5V to +10.5V and the resolution is 1 mV. The output impedance is <1Ω and the output cur-rent is limited to 10 mA. These outputs may be programmed from the front panel ([Aux Out])or via the computer interfaces.

X and Y The X and Y lock-in outputs are always available at these connectors. The bandwidth of these outputs is 100 kHz. A full scale input signal will generate ±10V at these outputs. The output impedance is <1Ω and the output current is limited to 10 mA.


GCentral
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Message 4 of 11
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Thanks for the reply.

please ignore the THz part. Im just using this labview software to view the analog data coming from the lock-in

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Can you show a screenshot of the 2V battery output? I'm surprised that it's the same, but if so, it makes the amplifier a less likely suspect (as you described).


GCentral
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