Newbie RC Filter Question

[KjellU]

Hi,

I have inherited a design with a low pass filter. Please see the attached schematic:



I appreciate any help I can get with how to calculate the cut-off-frequency for this filter.

Thanks for you help,
Kjell

 

[jiripolivka]

Your schematic shows no filter, it is simply a voltage limiter consisting of R 65 and CR 11 (a Zener diode). The capacitor is not necessary. If it might filter anything then one will need to know the Vin source impedance.

 

[SK245230]

Yes Jiripolivka is right. The zener diode is sometimes used as a regulator. Then the capacitor in your circuit is only for stabilising the source in order to avoid voltage drops.