Signal Output

Zeroing signal output

Self- ZERO setpoint

Referencing Figure 5•2for the +1 V output, note that using ZERO can increase dynamic range available for signal output by shifting an existing constant offset signal to a lower level (usually electrical zero). There are limits to this, however, so it is good practice to have background reduced as much as possible by minimizing column bleed, using clean supply gases, and by performing proper detector maintenance.

Figure 5-2

 

 

1 V Output: Canceling Baseline Offset (the

ZERO

function)

 

 

 

 

 

1.0 V maximumoutput level

 

 

O + 1.000 V

 

 

 

 

U

 

 

 

 

 

T

 

 

 

 

 

P

 

0.9 V usable

 

1.0 V usable

U

 

 

T

 

dynamic range

 

dynamic range

 

 

 

 

 

V

 

ZERO

ENTER

 

 

O

 

 

pressed

 

 

L + 0.100 V

 

 

 

 

T

 

Constant 0.100 V

 

 

A

 

 

 

 

detector background

 

 

G

 

 

 

 

signal

 

 

E

0 V

Š

 

 

 

 

 

 

 

 

 

HP 5890 SERIES II electrical zero

 

 

 

-0.010 V

 

 

 

 

 

 

Effect of ZERO

on the +1 V Analog Output

 

70