[sdiy] Square to Sine

[Magnus Danielson]

Hi Elaine,

On 04/04/2017 01:50 PM, Elaine Klopke wrote:
> Thanks for the info Tom!
>
> Magnus, the sources are fixed square waves coming from a set of PIC chips. So the fixed filtering doesn't bother me a bit. One filter for one frequency. What worries me is the volume drop.
>

If you use an op-amp as buffer (filter output to + input, output to - 
input) such as TL-072 you won't have much drop to worry about.

For pass-band you will have essentially no loading from the caps, and 
the op-amp will do nothing, so you will be close to unity gain then for 
the pass-band. It all depends on how the cut-off corner of the filter 
depends on the base frequency of the signal. If you think the loss will 
be a little too much, alter the feedback of the buffer op-amp to that of 
an amplifier with two resistors allows for the needed gain without 
making the design too complex.

Cheers,
Magnus