3
VOLTMETER RANGE CHANGE CONNECTIONS
APOLLO VOLTMETER INPUTS & CONFIGURATIONS
10
9
8
7
6
5
4
3
2
1
1M
75K
CW
25-turn built-in scaling pot, provides a continuously variable division rate of ÷1 through ÷13. When connected
in conjunction with the multi-tap voltage divider, direct readout from virtually any proportional transducer.
900K
90K
9K
1K
IN
V
÷10
÷100
÷1000
COMM.
0-1.999V
BASIC INPUT
115 VAC
50/60 HZ
POWER IN
Range Selection Jumper
Voltages over 1.999V are connected to
a multi-tap precision divider (Terminal 3
and 7) whose output is then jumpered
back to the basic 0-1.999V input. See
"Voltage Range Connections" below.
(+)
(-)
OPERATING POWER - Maximum power line variation ±10%
(Terminals
3 and 8)
Basic Apollo
Voltmeter
Input Range
0-1.999V
(+)
(-)
BASIC
VOLT-
METER
CIRCUIT
FRONT PANEL
FINE SCALE
ADJUSTMENT
PRECISION
MULTI-TAP
RANGE CHANGE
VOLTAGE DIVIDER
SCALING ADJ. POT FOR
NON-VOLTAGE READOUT
DECIMAL
POINT
SWITCHES
DISPLAY
The simplified schematic (left) shows all of
the features that permit the Apollo Voltmeter
to cover in-plant voltage related measurements.
The basic voltmeter range is 0 to 1.999 V. For
higher voltage readout, a multi-tap precision
voltage divider can be connected to extend the
range up to 300 V. A built-in scale adj. pot.
extends the capability of Apollo Voltmeters
even further to provide direct readout from
transducers that generate signal voltage
outputs proportional to RPM, PSI, FPM, etc.
Note: When used to readout in scaled units
other than voltage, the front panel adjustment
can be used as a fine trim scaling adjustment.
SCALING FOR DIRECT READOUT OF OTHER
VARIABLES
In many industrial applications, a voltage sensing instrument is required to
display a reading in terms of PSI, RPM, or some other variable. The signal
voltage being measured is normally generated by a transducer which senses the
variable and delivers a linearly proportional output voltage.
The multi-tap divider and the scale adj. pot. of the Apollo Voltmeters can be
connected in tandem
(series)
to scale
(divide)
virtually any signal voltage up to
300 V max. down to the basic 0 to 1.999 V input range to get the desired reading.
The multi-tap voltage divider provides coarse ranges of division and the scaling
pot. provides continuous selection of division factors between the taps.
Note: The normal decade division factors (÷10, ÷100, and ÷1000) have been
adjusted in this schematic to account for parallel connection of the scale pot.
resistance which increases these factors as shown.
In order to determine the jumper wiring configuration of the Apollo for a
scaled application, we must first determine the division factor required to
provide the desired display.
USING THE FORMULA:
VT x D.D.P. = D.F.
D.R.
10
9
8
7
6
5
4
3
75
K
900K
90K
9K
1K
12
105
1005
BASIC
VOLT-
METER
CIRCUIT
TRANS-
DUCER
MAX
VT
1M
V
SCALING
POT
1
13
WHERE:
VT = Maximum Transducer Output
D.D.P = Display Decimal Point
D.R. = Desired Reading
D.F. = Division Factor
D.D.P.
0.000
= 1
The Display Decimal Point
00.00
= 10
(D.D.P.) is determined by
000.0
= 100
the desired decimal point
0000
= 1000 placement in the readout.
Then we connect the divider and pot. to obtain the adjustable division range
we need to bracket the proper division factor
(See “Scaling Connection
Diagrams” below)
.
EXAMPLE 1:
A pressure transducer delivers a 5.5 V signal @ 120.0 PSI
maximum.
VT x D.D.P. = 5.5 x 100 = 4.58 D.F.
D.R. 120.0
This division factor falls between 1 and 12, so connect per
“Diagram A”
below. Calibrate by adjusting the scaling pot. to get the proper readout at a
known pressure.
SCALING CONNECTION DIAGRAMS
10
9
8
7
6
5
COMM.
1 ≤ D.F ≤ 12
Diagram C
Diagram A
Diagram B
Diagram D
12 ≤ D.F ≤ 105
105 ≤ D.F ≤ 1,005
1,005 ≤ D.F ≤ 13,000
VT
(+)
(-)
4
3
COMM.
3
6
4
5
7
8
(-)
T
V
9
10
(+)
(-)
COMM.
3
6
4
5
7
8
VT
(+)
9
10
10
3
6
4
5
7
8
9
(-)
COMM.
VT
(+)
EXAMPLE 2:
A tachometer generator delivers 210 VDC at maximum
machine speed which is to be indicated as 575 FPM on an Apollo Voltmeter.
210 V (Max. from tach. gen.) x 1000 (D.P.P.) = 365 (D.F.)
575 (Desired Readout)
This division factor falls between 105 and 1005, so connect per
“Diagram
C”
above. Calibrate by adjusting the scaling pot. to get the proper readout at a
known speed.
8
7
6
5
4
3
(+)
(-)
COMM.
0-1.999V
COMM.
3
(-)
4
5
8
(+)
6
7
0-19.99V
(3 & 8) 0-1.999V INPU
T
RANG
E
(3 & 7) 0-19.99V INPU
T
RANG
E
(3 & 7) 0-199.9V INPU
T
RANG
E
3
COMM.
4
5
(-)
8
6
7
(+)
0-199.9V
JUMPER
JUMPER
(3 & 7) 0-300V INPUT
RANG
E
COMM.
3
4
5
(-)
8
JUMPER
6
7
(+)
0-300V