Lakeshore DRC-70, DRC-70C, DRC-7C User Manual

User’s Manual

Model

DRC-70

Digital Cryogenic Thermometer

Model

DRC-7C/-70C

Digital Cryogenic Controller

Obsolete Notice:

This manual describes an obsolete Lake Shore product. This manual is a copy from our
archives and may not exactly match your instrument. Lake Shore assumes no responsibility for
this manual matching your exact hardware revision or operational procedures. Lake Shore
not responsible for any repairs made to the instrument based

on

information from this manual.

is

Lake Shore Cryotronics, Inc.
575

McCorkle Blvd.

Westerville, Ohio
E-Mail Addresses:

[e-mail]
[e-mail]

Visit Our Website:

www.lakeshore.com

Fax:

(61 4) 891 -1 392

Telephone:

Methods and apparatus disclosed and described herein have been developed solely on company funds of Lake Shore Cryotronics, Inc.

No

government or other contractual support or relationship whatsoever has existed which in any way affects or mitigates proprietary

rights

of

existing or applied for. Lake Shore Cryotronics, Inc. reserves the right to add, improve, modify,
modifications, or products at any time without notice. Lake Shore shall not be liable for errors contained herein or for incidental or
consequential damages

Obsolete

Lake Shore Cryotronics, Inc. in these developments. Methods and apparatus disclosed herein may be subject to US. Patents

in

connection with furnishing, performance,

Manual

43082-8888

[phone]

or

use

of

this

material.

USA

or

withdraw functions, design

October

1979

WA

LAKE SHORE CRYOTRONICS, INC. warrants each instrument of
its own manufacture to
and workmanship. Obligations under this Warranty shall
be limited to replacing, repairing
the purchase price, at
urned, shipment prepaid,
within ONE year of delivery to the original purchaser,
provided prior authorization for such return has been
given by an authorized representative of Lake Shore Cryo­tronics, Inc.

This

Warranty shall not apply to any instrument, which

inspection shall disclose to
become defective or unworkable due to abuse, mishandling,
misuse, accident, alteration, negligence, improper installa­tion,

likewise shall not apply to any instrument or component
not manufactured by others and included in Lake Shore Cryo-

tronics, Inc. equipment; the original manufacturer's warran-

ty

Lake Shore Cryotronics reserves the right to make changes
in design at any time without incurring any obligation

to install same on units previously purchased.

or

is

extended

other causes beyond our control. This Warranty

to

be

our

Lake Shore Cryotronics, Inc. customers.

R

R

A

NTY

free from defects in material

or

giving credit for

option,

to

our

our

of

any instrument ret-

factory for that purpose

satisfaction, to have

our

THERE ARE NO WARRANTIES WHICH EXTEND BEYOND THE DESCRIPTION

ON THE FACE HEREOF. THIS WARRANTY IS IN LIEU OF, AND

EXCLUDES ANY AND ALL OTHER WARRANTIES OR REPRESENTATIONS,

EXPRESSED, IMPLIED OR STATUTORY, INCLUDING MERCHANTABILITY

AND

FITNESS,

LIABILITIES OF LAKE SHORE CRYOTRONICS, INC., INCLUDING
BUT NOT LIMITED
PERSON,
SHORE CRYOTRONICS, INC. ANY ADDITIONAL OBLIGATION OR LIABIL-

ITY NOT EXPRESSLY PROVIDED FOR HEREIN EXCEPT IN WRITING DULY
EXECUTED BY

AS WELL AS ANY AND ALL OTHER OBLIGATIONS,

TO,

SPECIAL OR CONSEQUENTIAL DAMAGES. NO

OR

FIRM

CORPORATION

AN

OFFICER OF LAKE SHORE CRYOTRONICS, INC.

IS

AUTHORIZED TO ASSUME FOR LAKE

Table of Contents

Section Page

I.

General Information

1.1

Introduction

1.2 Description - General

1.3

Description - Specific

1.3.1

II.

III.

3.3.1

General Specifications

1.4

Major Assemblies Supplied

1.5 Accessory Equipment and Custom Options Available

1.6 Ordering

Installation

2.1 Introduction 6

2.2

Initial Inspection

2.3

Power Requirements 6

2.4 Grounding Requirements 6

2.5 Installation 6

2.6 Repackaging for Shipment

Operating Instructions

3.1

Introduction

3.2

Controls, Indicators, Connectors

3.3

Temperature Readout
Remote Parallel

3.4

Standard DT-500-DRC and DT-500CU-DRC-36 Curves

3.5

Calibration of the DRC-70/7C/70C Display 16

of

Replacement or Additional Sensors

BCD

Input/Output Option

1

1

2

2
4

4

4

6

8

9

9

15

15

16

IV.

V.

VI.

VII.

Theory

4.1

4.2

4.3

4.3.1

4.3.2

4.3.3

4.3.4

4.3.5

4.3.6

Troubleshooting

5.1

5.2

5.3

5.4

Parts

6.1

Appendices

of

Introduction

General Description
Detailed Description
Power Supplies
Precision Current Source

A/D

Converter

Microprocessor Hardware

Software
Digital Display Board

Introduction

Test

General Remarks

Instrument

List

DRC

Series

Operation

Equipment and

Tests

and Schematics

Parts

List

Accessories

and Schematics

21
21
21
21
24
24
24
25
31

33
33
33
33

40

Table

Reference Description Page

of Illustrations

Figure

Figure 1.2 Model DRC-70C Digital Cryogenic Thermometer/

Figure 2.1 Sensor Cable Diagrams

Table

Figure

Figure 3.2 DRC-70

Figure 3.3 DRC-7C/70C Front Panel

Figure

Table 3.2

Table

Figure

Figure

1.1

3.1

3.1

3.4

3.3

4.1

4.2

Model DRC-70 Digital Cryogenic Thermometer

Controller

Entry Number Correlation

DRC-70 Front Panel

Rear

DRC-7C/70C

BCD

Temperature Output - Remote

DT-

5

00-DRC Voltage - Temperature

Characteristic

Block Diagram

Block Diagram

Panel

Rear

of

of

Panel

I/0

DRC-70 22

DRC-70C 23

iv

V

7

9

11

12

13

14

17

18

Figure 4.3 Flow

Figure

Figure

Table

Figure

Table 5.2

Table

Figure

Figure 6.2

Figure 6.3 Display Board

Figure

4.4

4.5

5.1

5.1

6.1

6.1

6.4

Control Gain Function 30

Control Integral Function 30

DRC

DRC

Problem

Model

DRC-Circuit Schematic

DRC-Component Layout

DRC-L/A

Chart

Signals and Functions

Component Waveforms 36

DRC-Series

of

and Solution

Option Schematic

DRC-Software 26

34

38

Circuit Board Components

40
44

45

Schematic

46

47

SECTION

General Information

I

1.1

thermometer and
The DRC-7/70 series of instruments

DT-500-DRC and DT-500CU-DRC-36 silicon diode sensors manufactured by Lake

Shore Cryotronics, Inc.

this instrument. When ordering replacement sensors,
assure that the correct sensor curve

so

available

1.2

providing direct digital readout in kelvin temperature units and, for the
controllers, temperature control by direct digital comparison between the
displayed temperature, and a digital setpoint. The DRC-70 and DRC-70C display
temperature to

to

DRC

istics

Table
however, are useful to
Pre-selection allows the DRC-7/70
DT-500CU-DRC-36 sensors without adjustments of any kind. Since the standard
sensors
number of sensors with equal accuracy when selected

switch or multiplexer.

Introduction

is

a

The following

DRC-7C,

Several different diode sensor curves

that Lake Shore can assure the customer that replacement sensors

at

any

time

Description-General

The DRC-7/70

0.1

1

kelvin resolution.

The specified range

series

sensors which have been pre-selected to provide uniform character-

over this range. These sensors conform to the standard table (see

3.3)

to

0.5

are

interchangeable, the instruments may be used to read out any

series

kelvin resolution while the

R

or better over this temperature range. The instruments,

description of the DRC-70 cryogenic digital

DRC-70C cryogenic digital

are

designed to be used with the Model

is

specified. Multiple curves

in the future. For details, please

are

comprised of completely self-contained units

of

operation

1

K

although the accuracy

series

is

4.0

to be used with the DT-500-DRC and

thermometer/controllers.

are

designed for use with

care

must be taken to

see

DRC-7C

to

displays temperature

400

K*

utilizing standard

is

not

guaranteed below

through an appropriate

Section

are

needed

will

1.6.

be

4

K.

All

instruments contain a constant current source, for sensor excita-

is

tion, which

As

the sensor voltage. This allows the instrument user the ability to record the
sensor voltage versus

voltage directly. Since this output

recorder or voltmeter must be used to avoid loading
sensor
temperature may be determined to better than

One option

This

needs. Another option

for DRC-70 or

*

If possible, temperatures above
sensors since some

20

is

Four options

is

set

kelvin if heated above

preset

a

standard feature,

calibrated by the user or by

is

an analog signal which

to have

up

DRC-BCD-I/0

at

the factory

all

time

or to use a digital voltmeter to measure the sensor

at

units

is

Lake

10

microamps.

are

equipped with an analog output of

not buffered, a high input impedance

of

the sensor. If the

Shore Cryotronics, Inc.,

10mK.

are

available with the DRC-7/70

is

proportional to temperature (DRC-L/A).

a

sensitivity of

is

a

BCD

output of the displayed temperature (DRC-BCD-0

for the DRC-7C/70C). Included with the

330

of

these sensors may shift their values slightly below

330

kelvin.

10

mV/K

K

should be avoided with

but may be changed to the user's

series

of instruments.

BCD

DRC

series

output

option for the DRC-7C/70C instruments
the temperature
digital function generator. The third option
position, or ten position switch (DRC-SW­readouts. The DRC-70 has the switch mounted internally while the DRC-7C/70C
has the switch mounted in an external box. The fourth option
cut PROM (Programmable Read Only Memory) which corresponds to the calibration

curve of the customers DT-500
custom cut PROM
that any sensor may be used with this option,

restricted to the

set

point via

will

DRC

a

BCD

series

increase instrument accuracy to 0.1 kelvin. Please note

series

sensors.

is

the capability to remote program

signal from sources such

is

either a two position, five

2,

sensor.

5, or

A

10)

for multiple sensor

combination of calibration and

i.e.,

the customer

as

a

computer or

is

a

custom

is

not

1.3

instruments.

degrees with

designed system to
to 1 kelvin. Conformity to a standard
over the temperature range from 4.0 to 380

3850/3853 configuration and associated support circuits. The
stored in a PROM which can handle up to 32 break points. The data consists

of

straight line segments generate the

0.1

selected to conform to this curve to an accuracy

entire range.

1.3.1 General Specifications

when used with the standard DT-500-DRC or DT-500CU-DRC-36 temperature sensors.

Description-Specif

The following provides a description for the DRC-70 and DRC-7C/70C

The DRC-70 and DRC-70C provide direct temperature readout in kelvin

0.1

degree resolution. The DRC-70C controls in a properly

0.1

ic

kelvin. The DRC-7C has 1 degree resolution and controls

DRC

curve

is

better than 0.5 kelvin

K.

The DRC-7/70

a

table of temperature, voltage and slope between each break point. These

kelvin over the entire temperature range

The following specifications for the DRC-7/70

series

is

designed around an

DRC

curve to an accuracy

(4.0

F8

microprocessor using

DRC

of

better than

-

400

K).

of

better than

series

Sensors

0.5

are

curve

are

K

over the

applicable

a

is

General

Temperature Range:

Sensor: Silicon Diode (Model DT-500-DRC or DT-500CU-DRC-36)

Sensor Input:

Sensor Excitation:

Current Regulation: ±0.01%

Input Line Voltage:

Operating Environment:

Circuit Design: Integrated circuits, microprocessor controlled

:

1

to

400K

4

terminal connection, constant current excitation

Constant current 10 microamperes

115

V

10

-

45°C

(Accuracy not guaranteed below 4.0

or 230

V,

50

-

60

Hz,

switch selectable

K)

Input Impedance:

Weight:

Greater

5.9

Kg

than

(13

100

pounds)

megohms

Dimensions: 10.7cm

Temperature Readout:

Display:

Temperature Coefficient

Error:

Conformity To

DRC-70 Silicon Diode Table:

LSCI

Response

Standard

Resolution:

Time:

(4.2")

25.4cm

3

digits (for DRC-7C),

segment, non-blinking

4

digits (for DRC-70/70C),

segment, non-blinking

0.01

0.5

1

K

0.1

2.2

(10.01”)

K/°C

K

(4

for

DRC-7C

K

for DRC-70/70C

seconds to rated accuracy

high x 31.0cm

deep

-

400

K)

1.1cm

(12.2")

(0.43") high, 7

1.1cm

wide

(0.43") high,

x

7

outputs

Analog (Standard): Monitor output of sensor voltage

Analog (Optional): 10mV/K

Digital (Optional):

Temperature Control: (For DRC-7C/70C only)

Set

Point: Digital thumbwheel selection directly in

Set

Point Resolution:

Optional Remote Set Point:

Controllability:

Heater

Output:

:

at

<10

ohm output impedance

TTL

compatible parallel

kelvin temperature units

1

K

for DRC-7C and

TTL

compatible, parallel

1

K

(for DRC-7C) with a properly designed system

0.1

K

(for DRC-70C) with a properly designed system

Standard

0

-

46

watts,

0.1

BCD

K

for DRC-70C

BCD

0-1A,

0

-

46

VDC

Control Mode:

Time

proportional gain and

reset

1.4

the digital thermometer, the following:

DRC-7/70 instrument.

Major Assemblies Supplied

The DRC-7/70 series includes as standard equipment, in addition to

A. Operating and Servicing Manual.

B.

Five Pin Plug for Temperature Sensor Cables.

C. Three Pin Plug for Monitor of Sensor Output Voltage.

Model DT-500 series silicon diodes are not supplied as part of the

1.5

the factory. Items marked with an asterisk
should discuss these items with a factory representative before ordering.

Accessory Equipment and Custom Options Available

The following accessory equipment and custom options are available from

(*)

are of a custom nature, the customer

A. Extra Five Pin and Three Pin Connectors.

B.

19"

Rack Mount.

C. DT-500-DRC and DT-500CU-DRC-36 Silicon Temperature Sensitive Diodes

(Uncalibrated). (See data sheets at end of this manual for nominal

operating characteristics and case styles available).

D. DT-500-DRC Silicon Temperature Sensitive Diodes (Calibrated). Standard

laboratory calibration service for correlating diode output voltage
with diode temperature.
ation.

E.

Custom Modification

F.

Analog of Temperature (10mV/°K is standard).

G.

TTL Compatible Parallel BCD

Input

H.

Custom Cut PROM of calibrated DT-500 diodes series.

-

Standard with BCD output for DRC-7C/70C instruments).

of

See sensor data sheet for additional inform-

Sensor Current Supply Value.*

of

Temperature

(Also Remote Set Point

I.

Two Position, Five Position and Ten Position Switches for multiple

sensor readout. (Switch is mounted internally in DRC-70 instruments

(See Table

instruments

1.6

Model DRC-7/70 series instruments. These are the DT-500-DRC and the DT-500-CU­DRC-36 sensors. Their description is included in the cryogenic temperature

sensing elements brochure which is included in the back
reference numbers

instruments. The correct curve must be specified

will have its stated accuracy.

following ways

Ordering of Replacement or Additional Sensors

Two different sensor configurations are available for use with the

8

Three curves presently exist which can be used with the DRC series

:

and

3.1)

.

)

14

Switch is mounted in an external box for DRC-7C/70C

for dimensions of these sensors).

so

that your instrument

The proper curve may be determined in one of the

of

this manual (see

Specify the sensor

A.

with the instrument (serial number

plastic box in which the sensor

B.

Most instruments indicate the correct curve on the

number sticker located

DRC-70C-B-BCD-L/A.

specified,

both the

instrument.

C.

The third way

writing on

pondence between this writing and the appropriate curve:

e.

g

BCD

and analog of temperature option

PROM

Curve

serial

The B indicates that

.

,

DT-500-DRC-B.

is

to open your instrument and observe the

U13.

number that

was

on

the back

The

The following table gives the corres-

is

currently being used

is

found on the end of the

received).

of

the instrument, e.g.,

a

B

sensor must be

BCD-L/A

PROM

indicates that

are

U13

serial

on this

D. A

at

fourth way

4.2K

0

A B4
B B6

is

to measure the diode voltage for your sensor

DRC

Curve Sensor Voltage

0

A

B

B3

2.42

2.30

2.50

-

-

-

at

2.48

2.34

2.56

4.2

K

SECTION

II

Installation

2.1

Introduction

This section contains information and instructions necessary for the
installation and shipping of the model DRC-70/7C/70C Cryogenic Temperature
Indicators and Controllers. Included are initial inspection instructions,
power and grounding requirements, installation information and instructions
for repackaging for shipment.

2.2

Initial Inspection

This instrument was electrically and mechanically inspected prior

to

shipment.

It

should be free from mechanical damages, and in perfect working
order upon receipt. To confirm this, the instrument should be inspected
visually for obvious damage upon receipt and tested electrically by use
detect any concealed damage. Be sure

before discarding any shipping materials.

in transit, be sure

to

file appropriate claims with the carrier, and/or

to

inventory all components supplied

If

there is damage to the instrument

to

insurance company. Please advise the company of such filings. In case of

parts shortages, please advise the company. The standard Lake Shore Cryotronics

warranty is given on page iv.

2.3

Power Requirements

Before connecting the power cable to the line, ensure that the line

voltage selector switch

the line voltage to be used. Examine the power line fuse
is appropriate for the line voltage.

permissible line voltage fluctuation is

(115

V

or

230

V)

is in the appropriate position for

to

ensure that it

(115

V,

230

V

=

0.4

Amp) Nominal

±10%

at

50

to

60

Hz.

Caution: Disconnect line cord before inspecting or changing line fuse.

2.4

Grounding Requirements

To protect operating personnel, the National Electrical Manufacturer's

Association

and cabinets

(NEMA)

to

recommends, and some local codes require instrument panels

be grounded. This instrument is equipped with a three-conductor

power cable which, when plugged into an appropriate receptacle, grounds the

instrument.

2.5

Installation

The DRC-70 Thermometer and DRC-7C/70C Thermometer/Controller are all

solid state and do not generate significant heat.

It

may therefore be rack

mounted in close proximity to other equipment in dead air spaces. The heat

from such adjacent equipment should not subject the thermometer to an ambient
temperature in excess of 50°C

(122°F).

As

with any precision instrument, it
should not be subjected to the shock and vibrations which usually accompany
high vacuum pumping systems.

The recommended cable diagrams for the sensor diode and heater element

(in the case of the DRC-7C/70C controllers) are shown in Figure 2.1(a) and

(b).

introducing lead

The use of a four wire diode connection is highly recommended

IR

drops which will occur if the alternate two lead sensor

to

avoid

cable connection is used. For example, for a two lead connection, every 25
ohms of cable resistance corresponds to a

.1

K

error above

30

kelvin. The
alternate wiring scheme shown in Figure 2.1(c) may be used for the diode in
less critical applications where lead resistance can be kept small. The
indicated shielding connections are the recommended standard practice to
avoid ground loops.

2.6 Repackaging €or Shipment

Before returning an instrument to the factory for repair, please

discuss the malfunction with a factory representative.

He may be able to

suggest several field tests which will preclude returning a satisfactory

instrument to the factory when the malfunction is elsewhere. If it is
indicated that the fault is in the instrument after these tests, the repre-

sentative will send shipping instructions and labels for returning it.

When returning an instrument, please attach a tag securely to the

instrument itself (not on the shipping carton) clearly stating:

A.

Owner and Address

B. Instrument Model and Serial Number

C.

Malfunction Symptoms

D.

Description of External Connections and Cryostats,

If the original carton is available, repack the instrument in

plastic bag, place in carton using original spacers to protect protruding

controls, and close carton. Seal lid with paper or nylon tape. Affix

mailing labels and "FRAGILE" warnings.

If

the original carton is not available, wrap the instrument in
protective plastic wrapping material before placing in an inner container.
Place shock absorbing material around all sides

damage to protruding controls.
carton and seal with tape.

Place the inner container in a second heavy

Affix mailing labels and "FRAGILE" warnings.

of

the instrument to prevent

SECTION

Operating Instructions

3.1 Introduction

a

This section contains

their adjustment under normal operating conditions, and typical controller

applications. These instructions
installed as outlined in Section

2.1(a) in particular must be correct.

ohm heating element

2.1(b).

3.2 Controls, Indicators, Connectors

The operating controls, indicators and connectors on the DRC-70 and

DRC-7C/70C instrument's front and

3.3, and 3.4. The numbers with leaders

are

keyed to the entries in Table 3.1.

is

assumed to the

description of the operating controls and

are

II.

rear

III

based upon the instrument having been

The diode polarity

For the DRC-7C/70C instrument,

"Heater"

panels

to

terminals

are

shown in Figures 3.1, 3.2,

various controls in the figures

as

shown in Figure

as

shown in Figure

a

50

NO.

KEY

1

2

3

4

5 .25A

6

7

8

9

10

Table 3.1

NAME

NO

LABEL

NO

LABEL

POWER

115/230

50-60

NO

Remote

NO

Monitor Analog output of sensor voltage (0-2.5

Sensor

V

Hz

S.B.

LABEL

I/O

LABEL

-

Entry Number Correlation

FUNCTION

Digital. temperature display located behind

filter panel.

Ten position switch,

from one through ten (see Section 1.5(I)).

A.C.

A.C.

A.C.

Sensor input connector for sensors one
through ten.

BCD

A.C.

or optional linear analog output of temperature

recorder or voltmeter.

V+,

line switch (ON/OFF)
line voltage selector slide switch

line fuse

output of temperature (optional)

line cord

(0-4

V).

Sensor input lead terminals (Pin

Pin

B,

Maximum range

selects

(FUI)

Should be used with high input impedance

I-,

Pin

D,

V-,

1-400

sensor number

See

Section 1.5(f).

A,

Pin

H,

Shield).

K.

I+,

V)

Pin

E,

11

12

NO

NO

LABEL

LABEL

Same

as

Key

1

LED

to indicate when power

heater load.

is

applied to

NO.

KEY

NAME

FUNCTION

13

14

15

16

17

18

19

20
21
22
23

24

Heater

POWER

NO

LABEL

.75ASB-115
.4ASB-220

115/230

50-60

HI

/LO

Heater

Remote

NO

1.

OASB

Monitor

Sensor

V

HZ

I/O

LABEL

V

V

Fine tuning power control. Adjusts the

maximum power available from

or 0 to

on

rear

through use of vernier control.

Same

Digital

for

Same

Same

Limits
position) or

Heater

BCD

Same
Output power

Same

Same

20

watts

of instrument. Infinite resolution

as

Key

set

70C

and

as

Key

as

Key

maximum

element terminals

input of

as

Key

as

Key

as

Key

dependent on switch setting

3

point.

1

K

Has

resolution for

5

4

power to

20

watts

set

point/output of temperature

8

fuse

(LO

FU2

9

10

0

.1

K

resolution

50

watts

position)

to

7C.

50

(HI

watts

3.3 Temperature Readout

The sensor and heater should be installed following the suggestions

listed in the "Installation and Application Notes for Cryogenic Sensors"

brochure in Section

Connect the sensor to the instrument following the diagram in Figure

VIII.

2.1.

Turn the power switch to

proper temper

If

the following:

at

ur e re

the diode

Curve

0

la

t

ive to t he s amp

or

lead wires

A

B

If

the display reads one of the above and blinks, the diode
nected backwards.
higher in temperature from the

The sensor and readout display should follow Table 3.3 which illustrates
typical values expected of the standard DT-500-DRC
for your appropriate curve.

If the instrument or sensor does not agree with values listed in the
table, within the accuracy of the system, consult sections
and/or section

malfunction.

In

the case of an open lead, the display

on

troubleshooting to determine the cause and cure of the

ON

and observe that

1

e

temper a tur

are

shorted, the display

PROM

U13 Display

B3

B4

B6

last

voltage reading taken by the

the display shows the

e.

431.0

433.7

428.0

or

DT-500CU-DRC-36 sensors

will

will

on

read one

slowly drift

A/D

installation

of

is

con-

converter.

3.3.1 Remote Parallel

The

BCD

option consists of
and, for the DRC-7C/70C controllers,
kelvin degrees. The

3M connector on the

17

of Figure 3.4).

I.C.'s

Components Layout). Cutting of this jumper allows the user to enable

set

to the instrument provide

TTL

(or

two

U10 and

point by setting Pin-38,

levels of

1)

state

standard loads,

U11

and above capacitor C21 (see Figure

0.4

volts for the

under full load conditions.

BCD

rear

A

jumper

3.2

BCD

Input/Output Option

a

16

bit parallel output of temperature

a

14

bit

parallel

in and out

panel of the instrument (Key 7 of Figure 3.2 or Key

wire

J1

a

1-2-4-8 code using positive logic with standard

mA,

in the

is

handled through connector 53,

is

placed

high (see Table 3.2). Decade counters internal

low

(or

low

state.

on

the printed circuit board below

0)

state

The drivers are sufficient to sink

and 2.4 volts for the high

input of

6.4

-

DRC-7/70 Series

set

point in

a

40

a

pin

remote

3.4

Standard

DT-500-DRC

and

DT-500CU-DRC-36

Curves

The standard

Table

illustrates typical values expected of

The table also includes

in the linearization of the
readout.

3.5 Calibration of the DRC-70/7C/70C Display

3.5

calibrated in the following manner: the sensor current has been factory
calibrated to

without removing the instrument cover,

.01%

socket
resistor should measure a voltage equal to 10microamperes
the resistor. For example,

within

100

diagram, Figure

the

A

ideal ways to generate this voltage. If a resistor

varied until one

(A high impedance volt

appropriate voltage

trimpot

voltage source

display should be calibrated
should be used since the voltage sensitivity with temperature
higher temperatures (dV

pins shown
Key

3.3.

tolerance should be connected to pins A and B(Figure

K

resistor can be adjusted by varying resistor

A/D

variable

7

and

The sensor and readout display should follow Table

The

A/D

10

(J2). A

100

microvolts. If a recalibration

The

converter,

R20

Table

high input impedance volt

A/D

100

K

until the display reads the correct temperature. If a precision

is

3.2

are

for connector

17).

DT-500-DRC

a

list

(analog-to-digital converter) and current source can be

microamperes

6.4)

until correct reading

converter has also been calibrated

a

voltage has to be applied across pins E and D (Figure

resistor or precision voltage source in place of the diode

of

the break point voltages indicated in Table

meter

is

obtained, the display should be calibrated hy adjusting

used, a break point voltage should be dialed in and the

=

2.5

dT

gives the pin configuration for the

and

of

DRC

±10

DT-500CU-DRC-36

a

standard

PROM

curve to

nanoamperes. To check the sensor current

sensor voltages and breakpoints used

arrive

a

precision resistor of not less than

curve

DRC

at

the correct temperature

is

sensor to within

2.1)

meter

a

100

K±,01%

must be used for this adjustment).

as

above.

mV/K)

J1

(40

pin

resistor should read

A

break point temperature above

than for temperatures below

3M

connected to the precision

times

is

needed, the voltage across the

R12

(see component position

is

achieved.

at

the factory.

is

used,

BCD

I/O

connector on

rear

presented in

3.3

which

of the sensor

the value of

1.0000

it

is

option.

of

volts

To adjust

should be

3.3

is

After

lower

30

Kelvin.

instrument,

0.5

K.

2.1).

are

generated.

an

40

K

at

the

The

curve.

Table

3.3

shows a table of break point data for the standard

DRC

2

4

6

1

3

5

BCD

TEMPERATURE

BCD

TEMPERATURE

8

10

12

14

7

9

11

13

OUTPUT

Table 3.2

OUTPUT

REMOTE

16 18 20 22

15

17 19

21

-

MODEL

DRC

-

SERIES

I/O

24

26 28 30 32 34 36 38 40

23 25 27 29 31 33 35 37 39

BCD

TEMPERATURE INPUT

PIN

1

800

3

400

5

200

7 100

9

80

11

13 20
15 10
17
19 4

21

23

40

8

2

1

PIN

2

.1

4

.2

6 .4

8

.8

10

12
14 4
16
18
20 20

22 40
24

1

2

8

10

80

25 .8

27 .4
29

31

33
35 -15V

37

39 Digital Ground

.2

.1

Data

+15v

Valid

DC

DC

26 100

28 200
30 Not used

32 Not used
34 Analog Ground

36

Not used

38 Remote Control

40

+

5V

0 - Internal

l

-

External