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Easy to Customize Universal Low Pass Filter

PA3COR - Universal RC Low Pass Filter fc = 3.3KHz

A universal low pass filter that can easily customized, uses easy to obtain parts and has low power consumption. […]

1 transistor CW – filter

You cannot get it more simple than this, a 1 transistor CW filter. This filter is build according to the (surprise !) Multiple Feedback BandPass Filter (MFBPF) topology. Below, you see the circuit, originally designed by KE3IJ (alas now SK).

Transistor R1, R2 and R3 together with C1 and C2 form the standard MFBPF […]