Keithley 151 Instruction Manual page 3

SECTION 1 - INTRODUCTION
The Keithley Model 151 Null Detector is a stable, low-level DC
amolimwith high-~<~utesistance and low noise.
Careful shielding.
fiitering,
and gu&di.nk permit floating operation, as in a bridge nuli-
detector, with excellent rejection to extraneous voltages.
With a power sensitivity of lo-l7
watt, a re3pon3e speed of ""3
second, lack of overshoot and a zero-centered meter, the
151
may be used
,;n applications Inhere a suspension galvanometer might be employed, or
in other applicaticns where a galvanometer is not sufficiently sensitive,
fast or rugged.
Five non-linear ranges are provided which have the same center-
scale sensitiv'ty as the linear ranges, but are compressed in a quasi-
logarithmi: way to three decade3 on each range.
The3.e range3 permit
speedier null-searching th3.n the l~inear scales, without sncrlfizing
sensitivity at null.
Two zero controls for opera 2.r.d short-circuit inputs ai~low prop3r
zeroin,- for any Source resistance even in the presence of Bridge thermal
emfts eliminating the need for disconnecting bri~di=e voltage cc set zerr).
Although de?-:gned for nu?l detector applications, the Model
151
is
also useful as a dc voltmeter with 3 maximum full-scale sensi~isi~y ?f
100 microvolt3 and as an ,ammeter with a maxlm::m full-s,x1e ren:ii~tivL::.
of 10 micro-microamperes.
The 151 has i full-scale ouL.out of 10 volts at up to one mlliiamperc.
Thiv is sufficient Lo drive one milliar5~ere reco!.ders 'ii .well as ~iervo-
rebalance recorder3 and oscilloscopes.
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