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(passive?) reed relay noise filter

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fa_a2z

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Input-output, 1khz lpf activated.pngoutput, 1khz lpf activated.pngAudo input, random filter activated, ch1-I,ch2-O.png

Hi,

I was playing around with some variable frequency audio signal. The signal was fed into a reed relay before being fed into a passive low pass filter (1~5khz). The thing is, the signal seems to be "pre-filtered" by the relay as i got quite a clean 1khz signal output when using a 2khz low pass filter. I was expecting to see some noise, but it seems like there is none at all.
The relay datasheet can be found here:
https://www.farnell.com/datasheets/1693873.pdf

My question is:
1) if there is some noises in the range 0~50Hz(partly due to the supply i was using), how did this noise get filtered by a low pass filter with cutoff at 2khz?
2) is the relay even capable of filtering such noise?
 

If you are feeding your audio through the relay coil it will be filtered by its inductance. If it is being fed via the contacts, which are a straight through contact, there will be no filtering.
Frank
 
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    fa_a2z

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A relay alone does not affect the signal . It works as a bare switch.
A reed relay often has the contact tube separated from the coil by a thin aluminum foil to prevent any leakage from the coil upon the contact line.
If you can see any leakage between the contact and coil, separate carefully the external leads.
 
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