Tektronix 494A Water Dispenser User Manual


 
...Ttg
V_CO
output
!g
apptied
to
the
ctock
input
of
divide-by-s
counter
UaZZ.
'The
STROBE'er.raeLe
fin"
frgm
tlte
Error
Amplifier
permits
the
counter
to operate
when
the line
is
low
and
is
the
means
by wnich
the
microcomputer
can
turn
the
strobe
pufsed
on
or
off.
The
.counter
output
couples
throug'h
an-
impedance
matching
network
consisting
of
Ce0i0,
f_iOar,
C2Ogg,
and
C1032,
to
the
input
of
blndpass
ntier
fLzOO+.
fne
1Tp"g11g"^
matching
circuit
raises
the
tine
impedance
to
about
8200
ohms.
Theory
ol
Opera{on
-
4g4Al4S4Ap
Servtce,
Vol.
1
The
output
of
the
fitter
drives
another
impedance
matching
network
for
the
gat€
input
of
e2091.
The
out-
put
of
Q2091
drives
two
buffer
amplifiers
Ut091A
and
U10918.
Ul0918
drives
the
phase
Gate
circuitry.
and
Ul091A
is
reserved
for
future
applications.
Capicitors
Cl032
and
C2105 ar€
s_elected
to
provide
maximum
sig_
nal
amplitude
at TP20BZ.
7-87