Alim block:
The 1N4001 D1 diode is here to prevent reverse voltage accidents.
The 1.5k resistance R3 is used to give adequate power to the bypass led.
Condenser C3 is filtering the input.
P5, C2 and C7 is a charge pump montage based on an ICL7660S. It is used to
create the negative voltage from the positive voltage. For more information check
the ICL7660S datasheet.
Using a charge pump to create negative voltage has two advantages:
–
A bit less than 2x more headroom.
–
Virtual ground is avoided.
The drawback being it cannot supply a lot of op amps. The negative voltage drops
as more and more current is asked from the negative side.
Input buffer:
C12 is a decoupling cap.
This input stage acts as a high pass filter cutting at 1/(2xPIxR1xC1) = 48,22Hz.
It also acts to fix input impedance really high around R1 value: 1Mohms.
Then one part of the opamp is wired as a simple buffer.
Copyright Zorg Effects G.Denneulin december 2015 – For non commercial use only.
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