Simpson Electric Mini M135 Series Operation Manual
Minimum Depth Indicator - Less than 1.25” (31.75mm)
of Space Required Behind the Panel
Fits 3/64 DIN Cutout, 22mm x 68mm
3-1/2 Digit, 0.5” (12.7mm) High LCD
User-Selectable Decimal Point
Optional Negative Image, Bright Red Backlighting
12 Pin Mating Connector With 6” Lead Wires Included
for Easy Installation
Display Hold Standard on All Units
Four Voltage Ranges: 200mV, 2V, 20V, 200V
Three Power Supply Alternatives: 5VDC, ±5VDC, or
9VDC (With Low Battery Indication)
Mini M135 Series Digital Panel Meter
Installation and Panel Cutout
No mounting hardware required, snaps right into panel!
Mounting Requirements
The Mini indicators require a panel cutout of 2.68” (68mm) wide by
0.88” (22mm) high, and a panel area of 0.945” (24mm) high by 2.84”
(72mm) wide. The depth behind the panel, including terminals, is
0.7” (17.8mm). The front bezel protrudes 0.158” (4mm) from the
front of the mounting surface. The unit will snap-mount into panels
from 0.050” to 0.125” thick. A 12-pin connector with 6” wire leads is
included with each unit for quick installation.
Simpson’s Mini DC Voltage Indicators provide high quality,
accuracy, and reliability in a compact 12mm deep case.
M135 has a 3-1/2 digit, 0.5” LCD display and is available
with a negative image, bright red backlight option. Mini
M135s feature user-selectable decimal point and display
hold.
Three power supply choices are available, and a low battery
indication is provided for 9VDC battery applications. Mini
units feature a standard 3/64 DIN high-impact plastic case.
The standard LCD units have a clear viewing window. The
units with optional negative image, bright red backlighting,
have a red window.
DC Voltage
DISPLAY
Type: 7-segment LCD
Height: 0.5” (12.7mm)
Decimal point: 3-position programmable
Overrange indication: Most significant = “1”
Backlighting: Optional negative image, red
backlighting at 5, 10, 12, 24, or 48VDC
Polarity: Auto with “-” indication, “+” indication
implied
POWER REQUIREMENTS
DC Power: ±5V, +5V, and +9V
(Low battery indication provided with 9V units)
Power supply current: 2mA max
Backlight supply current: 50mA typical
For 24 and 48VDC, 10mA typical
ACCURACY @ 25°C:
±(0.1% of reading + 1 count)
ENVIRONMENTAL
Operating Temperature: 0 to 55°C
Storage Temperature: -10 to 60°C
Relative Humidity: 0 to 85% non-condensing
Warmup time: Less than 20 minutes
Temperature Coefficient: (All inputs)
⫾ (0.2% of input ⫾ 0.2 digit) /⬚C
NOISE REJECTION
NMRR: 60dB, 50/60Hz
CMRR: (with 1KV unbalanced @ 60 Hz): 90dB min
ANALOG TO DIGITAL CONVERSION
Technique: Integrating
Rate: 3 samples/second-typical
MECHANICAL
Bezel: 0.945” x 2.835”
(24mm x 72mm)
Depth: 0.473” (12mm)
Panel cutout: 0.874” x 2.677”
(22.2mm x 68mm)
Weight: 10oz (28.3g)
Case Material: 94-VO, UL rated ABS
Input Maximum
Range Resolution Impedance Input (unfused)
200
mV 100V >100M
⍀
50V
2V
1mV 10M
⍀
250V
20V
10mV 10M
⍀
250V
200V 100mV 10M
⍀
250V
Specifications
Connections
Safety Symbols
INPUTS: DC Voltage
These instruments are designed for maximum safety
to the operator when mounted in a panel according
to instructions. They are not to be used unmounted
or for exploratory measurements
in unknown circuits.
A reversed polarity power supply will permanently
damage this instrument.
IN HIGH and IN LOW must remain within the limits of
the power supply breakdown voltage.
No internal isolation is provided. Each meter requires
an isolated power supply. Supply voltage must also
be isolated from the circuit being measured.
A positive reading will be displayed when IN Hi is
more positive than IN Low.
Internal Reference: REFOUT must always be connected to REFIN unless an external reference is
being used.
External Reference: Connect between REFIN and
ANALOG GROUND; REFOUT should then be unconnected (open). For best results, external reference
voltage should be in the range of 50mV to 150mV.
System stability is then only as good as the external
reference.
Calibration
Model M135 has a limited range adjustment for calibration. Apply the appropriate current input for a
near full scale reading, typically 1900 counts on the
display. The adjustment is accessed through the
exposed hole in the upper left corner of the rear
panel. For this adjustment to function, REFOUT must
be connected to REFIN.
Backlight Power Supply
A 2-pin connector is included with the unit if backlighting is specified. The right pin is the Positive, and
the left pin is for the Negative power supply. See the
Rear Connections
diagram for location.
Mini M135
Rear Connections
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
5
VDC
Input Signal
+
-
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
-5
VDC
Input Signal
+5
VDC
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
Decimal Point
DP3
DP2
DP1
Decimal Point: DP 1 is the first decimal
point to the left of the least significant digit.
Connect DP# to Positive Supply to activate.
Unneeded features should remain unconnected.
Display Hold: The display can be held
indefinitely by connecting Hold to Positive
Supply. The display will function normally
when this connection is removed.
In Hi Analog Supply Negative REFIN DP2
Ground Ground Supply
Positive
In Low REFOUT Supply Hold DP1 DP3
9
VDC
Input Signal
+
-
±5 VDC Power Supply
+5 VDC Power Supply
9 VDC Power Supply
Optional Connections
The WARNING sign denotes a hazard. It
calls attention to a procedure, practice, or
the like, which, if not correctly performed
or adhered to, could result in personal
injury.
The CAUTION sign denotes a hazard. It
calls attention to an operating procedure,
practice, or the like, which, if not correctly adhered to could result in damage to or
destruction of part or all of the instrument.
Ordering Information
Non Backlight
Negative Image Red
Basic Unit Display DPM Power Supply Range Backlight Power
M135
0
1
2
0
1
0
1
2
3
4
5
11
12
13
14
3-1/2 Digit Indicator
+5VDC
±5VDC
+9VDC
200 mV
2 V
20 V
200 V
None
5VDC
10VDC
12VDC
24VDC
48VDC
Mini Voltage Indicators can be configured by making an entry for each box
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