This example is intended to illustrate the technical documentation of an electronic design produced by AIRBORN ELECTRONICS. Most of the technical drawings in this page have been reduced in resolution so they can be viewed easily. The full sized diagrams may be downloaded from our circuit collection.
All material contained in this document is Copyright ©2010 AirBorn Electronics.


Technical Design Manual

RCM Weighing


    Document Part 1

  • Specification
  • Circuit diagrams: RCM710 Main CPU
  • Parts List
  • Parts Key and Packages
  • Specific Parts notes
  • Front Panel art

    Document Part 2

  • RCM710 Interboard connector (CN15 Lead)
  • Factory only adjustment #5
  • RCM710 Connector pinouts
  • 87C552 Pinout definition, as used in RCM710 project
  • Drilling diagram: RCM710 CPU
  • Overlay diagram: RCM710 CPU
  • Circuit diagram: RCM710 Keyboard/Display PCB
  • Parts List: Keyboard/Display PCB
  • Drilling diagram: RCM710 Keyboard/Display
  • Overlay diagram: RCM710 Keyboard/Display
  • Overlay diagram: RCM710 CPU, colour

RCM710 Digital indicator specification (Revised)

    Standard Features

  • The RCM710 setup functions and calibration sequences are programmed through the in-built keyboard and display. Setup and calibration may be disabled by an internal hardware jumper.
  • Displayed resolution: Up to 1 part in 10,000.
  • Automatic zero maintenance: Maintains a stable zero.
  • Push-button zero: Zeros the gross value to within plus/minus 2% of the capacity of the scale
  • Digital filter: Provides the ability to digitally compensate for extreme motion or vibration.
  • Automatic weight identification: Net, Gross and Zero indication is provided via the display.
  • Keyboard enterable Tare.


6 digits or 5 digits with a leading minus sign. The display is a blue-green vacuum fluorescent type, with characters 13mm high.
Decimal point location:
Setup through the keyboard to display:
Increment size ('Count by'):
X1,X2,X5,X10,X20 or X50 (Maximum set by Full Scale Increments)
Full Scale Increments:
Choice of: 1000,2000,2500,3000,4000,5000,6000,8000 and 10000.
Zero Indication:
"Zero" indicator illuminates when scale is within +/-0.25 increment of gross zero.
Over capacity:
Display will blank if scale is over 2 increments above programmed scale capacity.
Under zero display:
Display will blank if scale is 2 increments under zero.
Initial/Span range:
Initial range is 0 to 20 millivolts; span range is 5 to 30 millivolts, both referenced to a 30 millivolt load cell output. The span range may be increased to 45 millivolts for use with 3mv/V load cells through an internal shorting jumper.
0.50 microvolts per increment minimum.
Up to 1 part in 10,000 displayed, Up to 1 part in 100,000 internal.
Load Cell Excitation:
Provided for up to six 350 ohm or eight 725 ohm load cells. Load cell excitation voltage is nominal 12.5 volts.
[To be determined by NSC test]
Operating range:
[To be determined by NSC test]. Target: -10 to 40 degrees Celsius at 10 to 95% relative humidity, non-condensing.
Motion detection:
The Zero and Tare functions are inhibited while the weight display is changing.
Automatic zero maintenance:
Weight indication within +/- 0.1 increments of the centre of zero is compensated to zero. Total compensation range is 4% of full scale. Weight variations which occur at a rate of 0.1 increments per second or slower will be compensated.
Digital Filter:
Selectable (through the keyboard) to reduce the effects of vibration and extreme motion. 4 settings are available.
Display Verification:
Depressing the "test" button causes a test pattern to appear on the display, testing all segments, decimal points and arrows for correct operation.
Tare entry and operation may be disabled by programming.
Power requirements:
240VAC 50Hz. Power consumption is 15 watts (or less).

Revised RCM710 Digital indicator specification. 24 February 1994

RCM710 CPU Board Parts list

RCM1_1.PCB  22:28  17-8-1996      PCB Parts List

A1                                                     LOGO1
BR1                1A 100V                             WO-1
BR2                1A 100V                             WO-1
BR3                1A 100V                             WO-1
BR4                1A 100V BR                          WO-1
C1                 0.2UF FILM                          RAD0.3
C2                 47NF FILM                           RAD0.3
C3                 22NF FILM                           RAD0.3
C4                 0.15 P1840                          RAD0.4
C5                 22UF16V TN                          RB.1/.2
C17                22UF16V TN                          RB.1/.2
C18                22UF16V TN                          RB.1/.2
C6                 220PF                               RAD0.1
C7                 100PF                               RAD0.1
C8                 100PF                               RAD0.1
C9                 0.1UF                               RAD0.1
C10                0.1UF                               RAD0.1
C11                0.1UF                               RAD0.1
C12                0.1UF                               RAD0.1
C13                0.1UF                               RAD0.1
C26                0.1UF                               RAD0.1
C27                0.1UF                               RAD0.1
C28                0.1UF                               RAD0.1
C34                0.1UF                               RAD0.1
C35                0.1UF                               RAD0.1
C36                0.1UF                               RAD0.1
C14                470UF 63V                           RB.3/.6
C15                2200UF 35V                          RB.4/.8
C16                4700UF 16V                          RB.4/.8
C19                10UF25V TN                          RB.1/.2
C20                10UF25V TN                          RB.1/.2
C21                10UF25V TN                          RB.1/.2
C22                10UF35V                             RB.2/.4
C23                33NF                                RAD0.2
C24                33NF                                RAD0.2
C25                2.2UF 50V                           RB.1/.2
C29                22PF                                RAD0.2
C30                22PF                                RAD0.2
C31                2.2UF 16V                           RB.1/.2
C32                3.3NF                               RAD0.2
C33                0.5F SUPER                          SUPERCAP
CN1                TRANSFORMER                         PHOENIX10H
CN2                LOAD CELL                           PHOENIX8H
CN3                BUS COM'S                           PHOENIX3H254
CN4                FEATURE PCB                         SIP8
CN5                RELAY PCB                           SIP8
CN6                PRINTER PCB                         SIP6
CN7                ANCILL RS232 PCB                    SIP8
CN8                SYSTEM RS232 PCB                    SIP8
CN9                I2C CONN A                          SIP5
CN10               I2C CONN B                          SIP5
CN11               PRINT SW                            PHOENIX4H254
CN12               ANOUT                               SIP4
CN13               CHASSIS POST                        SPADE
CN14               ALT LC PCB                          SIP10
CN15               DISPLAY-KEYBOARD                    IDC26
CN16               VTEST                               SIP2
D1                 BAW62                               DIODE0.3
D2                 BAW62                               DIODE0.3
D10                BAW62                               DIODE0.3
D11                BAW62                               DIODE0.3
D12                BAW62                               DIODE0.3
D14                BAW62                               DIODE0.3
D17                BAW62                               DIODE0.3
D18                BAW62                               DIODE0.3
D19                BAW62                               DIODE0.3
D4                 6.8V 400MW                          DIODE0.4
D5                 15V 1.3W                            DIODE0.7
D6                 15V 1.3W                            DIODE0.7
D7                 LM385Z2.5                           TO-92A
D8                 1N4002                              DIODE0.4
D9                 1N4002                              DIODE0.4
D13                5.6V 400MW                          DIODE0.3
D15                10V 1.3W                            DIODE0.4
D16                5.6V 1.3W                           DIODE0.4
IC1                LTC1051                             DIP8
IC2                LTC1051                             DIP8
IC3                LTC1051                             DIP8
IC4                TLC2274                             DIP14
IC5                LM339                               DIP14
IC6                4051                                DIP16
IC7                4053                                DIP16
IC8                74HCT74                             DIP14
IC9                87C552                              PLCC68SKT
IC10               PCF8583A                            DIP8
IC11               PCF8582A                            DIP8
IC12               75176                               DIP8
J1                 LDCELL LNK                          SIP3
J2                 PROG LINK                           SIP3
J3                 TERMIN LNK                          SIP3
LED1               RED DIAG LED                        LED5
LED2               GRN DIAG LED                        LED5
R1                 100K 0.1%                           AXIAL0.4
R2                 100K 0.1%                           AXIAL0.4
R5                 100K 0.1%                           AXIAL0.4
R8                 100K 0.1%                           AXIAL0.4
R3                 1K                                  AXIAL0.4
R4                 1K                                  AXIAL0.4
R11                1K                                  AXIAL0.4
R12                1K                                  AXIAL0.4
R19                1K                                  AXIAL0.4
R21                1K                                  AXIAL0.4
R44                1K                                  AXIAL0.4
R46                1K                                  AXIAL0.4
R59                1K                                  AXIAL0.4
R60                1K                                  AXIAL0.4
R6                 750E 0.1%                           AXIAL0.4
R7                 750E 0.1%                           AXIAL0.4
R9                 3K 0.1%                             AXIAL0.4
R10                475K                                AXIAL0.4
R14                475K                                AXIAL0.4
R13                59K                                 AXIAL0.4
R15                243K                                AXIAL0.4
R16                10K                                 AXIAL0.4
R20                10K                                 AXIAL0.4
R28                10K                                 AXIAL0.4
R33                10K                                 AXIAL0.4
R17                ?? 0.1%15P                          AXIAL0.4
R18                30K EST.                            AXIAL0.4
R22                500K                                AXIAL0.4
R23                500E                                AXIAL0.4
R24                5K                                  AXIAL0.4
R25                4.7K                                AXIAL0.4
R26                4.7K                                AXIAL0.4
R38                4.7K                                AXIAL0.4
R72                4.7K                                AXIAL0.4
R27                1M                                  AXIAL0.4
R76                1M                                  AXIAL0.4
R34                27K                                 AXIAL0.4
R35                22K                                 AXIAL0.4
R36                22K                                 AXIAL0.4
R37                22K                                 AXIAL0.4
R58                22K                                 AXIAL0.4
R68                22K                                 AXIAL0.4
R69                22K                                 AXIAL0.4
R70                22K                                 AXIAL0.4
R71                22K                                 AXIAL0.4
R73                22K                                 AXIAL0.4
R74                22K                                 AXIAL0.4
R75                22K                                 AXIAL0.4
R39                1.2K 1%                             AXIAL0.4
R54                1.2K 1%                             AXIAL0.4
R40                110E 1%                             AXIAL0.4
R49                110E 1%                             AXIAL0.4
R51                110E 1%                             AXIAL0.4
R53                110E 1%                             AXIAL0.4
R41                1.8E                                AXIAL0.4
R42                1.5E                                AXIAL0.4
R43                180E                                AXIAL0.4
R45                47K 1%                              AXIAL0.4
R47                47K                                 AXIAL0.4
R48                47K                                 AXIAL0.4
R50                3K 1% 0.5W                          AXIAL0.4
R52                330E 1%                             AXIAL0.4
R56                56K                                 AXIAL0.4
R57                2.2M                                AXIAL0.4
R61                220E                                AXIAL0.4
R62                100E                                AXIAL0.4
R63                10E FUSIBLEX3                       AXIAL0.4
R64                10E FUSBLE                          AXIAL0.4
R65                10E FUSBLE                          AXIAL0.4
R66                1.5K                                AXIAL0.4
R67                1.5K                                AXIAL0.4
R77                10K 0.1%                            AXIAL0.4
R78                10K 0.1%                            AXIAL0.4
R79                10K 0.1%                            AXIAL0.4
R80                30K 0.1%                            AXIAL0.4
R81                30K 0.1%                            AXIAL0.4
R82                30K 0.1%                            AXIAL0.4
SIP1               10K                                 SIP9
TR1                BC337                               TO-92A
TR2                BD140                               TO-126
TR3                BC549C                              TO-92A
TR4                BC549C                              TO-92A
TR5                MPSA13                              TO-92A
VDR2               D223512-22                          TO-92A
VR1                LM317T                              TO-220
VR2                LM317T                              TO-220
VR3                LM317T                              TO-220
VR4                LT1021                              DIP8
VR5                LM317LZ                             TO-92A
XTAL1              11.0592MHZ                          XTAL1
XTAL2              32.768KHZ                           XTAL32
Total Components = 183

    Additional parts:

  • 68 pin PLCC socket, pin grid array type, gold flash for part 87C552
  • 8 pin DIP IC socket, turned pin machine screw type for part 75176
  • Shorting plugs for each of the "Jxx" jumpers, 0.1 inch pitch two pin gold plated
  • Mating connectors for CN1, CN2, CN3, CN11 as detailed in "Specific parts notes"
  • Cable assembly per "CN15 interboard connector" specification
  • PCB Laminates, RCM710 CPU AB9301027 and Keyboard-display AB9301027
  • Transformer, per "RCM710 Transformer specification"
  • Mains Filter Roxburgh RX730AE or equivalent
  • Mains VDR Philips 2322 595 52716 or equivalent
  • 4 Way covered mains wiring block
  • 15 Amp 32mm fuse holder, chassis mount
  • 1 Amp 240v 32mm fuse

Part Key:

Bridge Rectifier
Integrated circuit
Selection jumper (3 0.1 inch pitch posts and one shorting plug)
Light emitting diode
SIP resistor network (Resistors to one common terminal, pin 1)
Voltage regulator


Axial package, lead pitch 0.4 inches when formed
Polarised axial package, lead pitch 0.3 inches when formed
Polarised axial package, lead pitch 0.4 inches when formed
Polarised axial pack, lead pitch 0.7 inches, body width 5.5mm
8 pin dual in line package
14 pin dual in line package
16 pin dual in line package
18 pin dual in line package
NEC Fluro display, 0.1 inch lead pitch, 20 pin, special pack
26 Way 0.1 x 0.1 inch dual row horizontal connector for IDC
Special IR rx package, 3 pin (like TO-92) 0.1 inch lead pitch
Special LDR package, radial, 5mm lead pitch
5mm diameter 2.5mm pitch LED (Note 3mm dia LEDs also fit holes)
12mm square tactile push button, 5mm x 12.6mm mounting pitch
3 Way 0.2 inch pitch horizontal connector (Can take an unpluggable screw terminal connector if required)
4 Way 0.2 inch pitch horizontal connector (Can take an unpluggable screw terminal connector if required)
8 Way 0.2 inch (Note: Not 5mm) pitch horizontal connector (Can take an unpluggable screw terminal connector if required)
10 Way 0.2 inch (Note: Not 5mm) pitch horizontal connector
68 pin PLCC socket, 0.1 x 0.1 inch pitch pin grid
Radial leaded package, lead pitch 2.5mm
Radial leaded rectangular package, 5mm lead pitch
Radial leaded rectangular package, lead pitch 0.3 inches
Radial leaded rectangular package, lead pitch 0.4 inches
Polarised radial package, diameter 5mm or less, lead pitch 2.5mm
Polarised radial package, diameter 10mm or less, lead pitch 5mm
Polarised package, diameter 15mm or less, lead pitch 0.3 inches
Polarised package, diameter 20mm or less, lead pitch 0.4 inches
2 Way 0.1 inch pitch single row package
3 Way 0.1 inch pitch single row package
4 Way 0.1 inch pitch single row package
5 Way 0.1 inch pitch single row package
6 Way 0.1 inch pitch single row package
7 Way 0.1 inch pitch single row package
8 Way 0.1 inch pitch single row package
9 Way 0.1 inch pitch single row package
10 Way 0.1 inch pitch single row package
PCB Mount 5mm pitch two prong mounting brass spade terminal
Polarised package, 21mm diameter, lead pitch 5mm
Standard TO-92 package mounted on 0.1 x 0.1 inch pitch pads
Standard TO-126 package, mounted on 0.1 inch pitch lead spacing
Standard TO-220 package, 0.1 inch pitch leads, M3 mounting screw
10 turn horizontal long body preset pot, 12.6mm pin spacing
Bridge rectifier, 10mm diameter, lead pitch 0.2 x 0.2 inch
Standard HC49 crystal can, vertical mount (horizontal if space)
Watch crystal

Specific parts notes:

  • Capacitors suffixed by "Tn" are tantalum type.
  • Capacitors C14, C15 and C16 should not exceed 32mm in length or 16mm in diameter
  • Capacitors with higher voltages may be substituted, provided they physically fit
  • Do not substitute P1840 capacitor. Each brand requires approval.
  • Parts 0.5F supercap, 32khz crystal and PCF8583A are only required for Clk option
  • PCF8583A is a Philips part
  • CN1 is to be 0.2 inch pitch wafer connector, not 10 way screw terminal
  • Kit both PCB mount socket and screw terminal plug for CN2, CN3, CN11
  • See connector pinouts for suggested connector part numbers, details are:
  • CN1 10 Way 0.2 inch pitch wafer connector
  • CN2 8 Way 0.2 inch pitch Weidmuller-Klippon SL8-H or equivalent
  • CN3 3 Way 0.2 inch pitch Weidmuller-Klippon SL3-H
  • CN11 4 Way 0.2 inch pitch Weidmuller-Klippon SL4-H
  • CN15 26 Way 0.1 x 0.1 inch Insul. Displacement connector, Fujitsu FCN744P034AUR
  • CN4,5,6,7,8,9,10,12,14,16,J1,J2,J3 0.1 inch pitch gold plated single row posts
  • Diodes that specify just voltage and wattage (e.g. "15V 1.3W") are zener type
  • Diode type 1N4002 may be replaced with 1N4003-1N4007
  • Device 87C552 needs to be programmed prior to insertion into the 68 pin PLCC pin grid array socket
  • LEDs should be water clear package super/ultra bright or high intensity
  • All resistors are 1% 0.25w metal film type unless otherwise specified
  • Substitution of standard resistors where fusible types are specified could cause a fire hazard or damaged circuitry under fault conditions
  • VDR2 D223512-22 is a Murata part
  • All ICs are DIP plastic package types, unless otherwise specified
  • LT1021 is a linear technology voltage reference part - type LT1021CN-8
  • LTC1051 is a linear technology chopper amplifier part - type LTC1051CN-8
  • TLC2274 is a Texas Instruments premium op-amp part - type TLC2274ACN
  • LM339 should be substituted with LM339AN where possible
  • PCF8582A is a Philips 256 x 8 i2c EEPROM, or Arizona 85C82P. Do not use 93C56.
  • 75176, use SN75176AP or LTC485, but is only necessary for RS485 option
  • Each brand of 4051/4053 may have to be tested for RON variation before approval
  • 11.0592MHz crystal is an AT-cut part
  • 32.768kHz crystal is a standard watch part
  • FIP6A13A is made by NEC
  • SA594 may be substituted with NE594, HA16617P, (M54564P with link changes)
  • Key-Sw is type SKHKAA, many types are physically compatible
  • IRRX is type Sharp IS1U60, but is only necessary for IRRX option
  • Piezo is murata PKM22EPP-4001 or physically compatible sounder (NOT buzzer)
  • LDR is NSL19-MS51 type, but is only necessary for LDR option
  • Dew sensor is two gold plated 0.1 inch posts mounted with epoxy on plastic sheet with flying leads, and is only necessary for dew sensor option
  • Tilt switch is Farnell part number 170855, and is only necessary for tilt option
  • NTC is Philips part number 2322-640-66472, and is only necessary for NTC option

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