Keithley 244 Instruction Manual page 15

MODEL 244 HIGH VOLTAGE SUPPLY
ACCESSORIES
Theory of operation far Model
2441: (See Schematic
24640A.)
a. The Model
2441
Option provides current limiting
control when used with a ,,icoammeter with a 1 volt
output. The Overload Protection Input 5201 requires
an input signal between 1.4 to 2.0 volts d-c.
The
Model
2441
circuit activates the Model 244 control
circuit by meant of transistor switch Q202. The
Model
2441
filter circuit prevents false overloads
due to 60 Hz noise while not affecting the response
which is approximately
0.25
seconds (10-W% rise
the).
b. 'rhe
2441
Circuit is composed of an emitter
fallower transistor
Q201
which drives a transistor
switch
Q202
which is paralleled wieh the Model 244
overload transistor switch 4107. A filter circuit
is composed of R203 and C2Ol.
Replaceable Parts for Model 2441:
C*l-C"it
Mfr. Mfr. Keithley
oesig. oescription Code oesig. Part NO.
5201 COll"eCtOr
APH so-PC2M
a-233
--
Cable, 3 ft., k&es
with 5201) K-I -- 3991
Q201 Transistor F-I
2N3565
'i-G-39
Q202
Transistor F-l
2N3565
'K-39
R201 Resistor,lMn,l0%,1/2W A-B EB Rl-1M
R202 Resistar.3.9Kn.l0%.1/2W A-B EB Rl-3.9K
R203 ~~~~~~~~~ m,io%,i/2w ~-8 EB n-x
R204
Resistor,
10Kn,10%,1/2W
n-B EB Rl-1OK
R205
Resistor,100K~,10%,1/2W h-B EB Rl-100K
c201
Capacitor, 22ufd,20" u-c
K22JZOK
CSO-2x4
-_
Stand off K-I --
ST-25
5107
COll"eCt'X
K-I -- SpCXid
FlClmE 7.
Overload Protection circuit Diagram.
0976