change (50+sinXt) to (50+absolute value(sinXt))

[ktec1]

hi
just i want to change first signal to second
a point is that the circuit that analyse the second wave shape has a
very high input resistance for both dc and ac (about 4.7M ohms)
X can be about 125 but i dont believe that to be important
thanks for suggesions and expriences

 

[Kral]

ktec1,
Run the input signal through a low passfilter and a high pass filter. The output of the low pass filter yields the DC component (in this specific case, 50). Run the output of the high pass filter thru a precision rectifier (there are lots of circuits on the web). Sum the outputs of the low pass filter and the precision rectifier using a simple op-amp summing circuit.
Regards,
Kral

 

[bunalmis]

absolute[(50+sinXt)-50] + 50 = (50+absolute value(sinXt))

 

[ktec1]

dear bunalmis yau have talked the math meaning of what we want to do
separating dc and ac then full wave rectifing ac and adding them
dear kral you have exactly analysed what i want
lets talk about extra lowpass filter ,its so easy with a serie capacitor
then please guid me for a high pass for a 20hzs signal, a serie inductor??(how much inductance) our circuit should have about 4Mohms input resistance
to both dc and ac
please tell how to make that high pass filter
in this case frequency has been important
my last question,i really have problems with opamps
how can i add a 50 volts dc with any signal with a lm324 with bias with 5 and zero,
please guide with a example circuit .
lets make the problem easier if i have only positive part of the sine wave it would
satisfy the circuit, dc+only positive part, even if the positive part to be doubled
thanks for any suggestion