Simple passive low pass filter

[Dougster]

I'm wondering if one of you math wizards might help me. I want to make a simple, basic low pass filter (1 cap and 1 resister) to block any frequencies above about 300 cps. I found some formulas, but I get lost in the capacitive reactance and impedance stuff. I would like to use a low value resistor if possible. Input is about 210 volts @ 200 cps. Any ideas? Even approximate values would help. Thanks for any help you might give me.
Regards,
Doug

 

[Gryd3]

I'm wondering if one of you math wizards might help me. I want to make a simple, basic low pass filter (1 cap and 1 resister) to block any frequencies above about 300 cps. I found some formulas, but I get lost in the capacitive reactance and impedance stuff. I would like to use a low value resistor if possible. Input is about 210 volts @ 200 cps. Any ideas? Even approximate values would help. Thanks for any help you might give me.
Regards,
Doug

Is this a low power application?
There are calculators all over the net for audio nuts to calculate values for High-pass, Low-pass and Band-pass filters.

 

[luca_zzz]

R*C = 10 * (1/300) sec

 

[Dougster]

No, it's not low power. Thanks luca_zzz. That looks simple enough! I'll try it!!!

 

[LvW]

"...to block any frequencies above about 300 cps."

I suppose you know that it is not possible "to block" frequencies above the so-called "cut-off" frequency.
A first order RC lowpass - as envisaged by you - attenuates unwanted frequencies only with an attenuation rate of 20dB/decade.
For better attenuation you need a higher order filter.

 

[BobK]

10 Ohms, 47uF for a cutoff of 338 Hz.

Of course, cutoff frequency is the frequency where the response will be down by 3dB, then 6dB per octave after that.

Edit:

or 1 Ohm 470uF
or 100 Ohm 4.7uF
etc

Bob