Choke design

Xl=2*PI*F*L Calculate for a high value of Xl

It's easier to find what values of L are available to you at a reasonable cost unless you intend to wind your own.

Factors: the choke current rating and DC resistance. Get the highest value of inductance that will handle the current for maximum attenuation of the ~ 1MHz signal. Check that the DC resistance of the choke will not impact circuit operation beyond specs.

For example, a 2.2 mH choke from Mouser (542-5900-222-RC) will handle 500mA, but with 2 ohms DC resistance, you'll get a 1 volt drop across it at 500 mA. Depending on where that is in the circuit, it might be unacceptable.

Ed

"bubbles123"

This is not an easy double requirement to meet because all chokes have self capacitance - the larger the value the more capacitance it has - resulting in a self resonant frequency that may well be below 1 MHz and ruin the wanted blocking effect.

Normal practice is to use a low value choke wired in series PLUS a capacitor wired in * parallel * to filter DC power. It is easy to find capacitors with very low impedances at and around 1 MHz - ie most electros of over 100uF.

...... Phil