22
b. Charge Pump (U4): The charge pump (also known as a boost converter) takes the +9 volts
from the power supply and turns it into -9 volts. This way, the opamps in the signal path can
operate between -9V and +9V, giving the signal a total of 18V to work with.
This IC is labeled 7660S, has 8 pins and is polarized. The little divot on one end of the IC
should be placed closest to the white dot silk-screened on the PCB (44). You may have to
slightly bend the pins in to get them to seat in the holes on the PCB. The holes for U4 are
very close to some of the solder pads of J2; when soldering this IC, it helps to keep the
soldering iron away from the pads of J2 by only touching the iron to the inside of the pins of
U4 (45).
44
45
46
47
You will install the last IC, the Hall effect sensor, onto the sensor PCB later.
5. DIP Switch (S2): “DIP” stands for “Dual In-line Package,” which describes the pin layout on these
miniature switches. When installing them, make sure the labels on the switch line up with the
markings on the PCB (48). Hold the switch in place with your finger and tack one pin in place
(49). Now set down the board or place it in your clamp and solder the rest of the pins properly.
48
49
