====== Multi lowpass filter ======

Multiple [[https://www.electronics-tutorials.ws/filter/filter_2.html|RC lowpass filters]] with different cutoff frequencies to switch between.

===== Application =====

  - Vibration sensitivity measurement 
  - Errorsignal for Locks

{{:groups:mg:multi_lowpass_top_view.jpeg?300|}}{{:groups:mg:multi_lowpass_side_view.jpeg?300|}}{{:groups:mg:multi_lowpass_bottom_view.jpeg?300|}}{{:groups:mg:multi_lowpass_inside_view.jpeg?300|}}

===== Status =====

:OK:: tested and working, :Ok:: minor issue/not tested, :no:: defect

^ #   ^ Status  ^ Comment  ^
| 1   | :OK:    |          |
| 2   | :OK:    |          |
| 3   | :OK:    |          |
| 4   | :OK:    |          |
| 5   | :OK:    |          |
| 6   | :OK:    |          |
| 7   | :OK:    |          |
| 8   | :OK:    |          |
| 9   | :OK:    |          |
| 10  | :OK:    |          |
| 11  | :OK:    |          |

===== Setup =====

{{:groups:mg:multi_lowpass_schematic.jpg?400|}}

**Switch:** Elma 01-1104 (with gold inside), Farnell # 1876072

\(f_{c}\): cutoff frequency, \(\tau\): time constant, R: resistance, C: capacitance

\[ f_{c} = \frac{1}{2 \pi \tau} \quad with \quad \tau = RC\]

^ Cutoff Frequency [Hz ]  ^ Time Constant [ms]  ^ Capacitance [nF]  ^ Capacitor             ^
| 4.8                     | 33                  | 3300              | WIMA 3,3µF 50- F6     |
| 16                      | 10                  | 1000              | WIMA MKS4 1,0µF 100-  |
| 48                      | 3.3                 | 330               | WIMA MKC4 0.33/100-   |
| 160                     | 1                   | 100               | µ1K100                |
| 480                     | 0.33                | 33                | 33nK100               |
| 1600                    | 0.1                 | 10                | 10nK100               |


===== Prototype =====

Multi RC lowpass filters by PTB

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