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Bayham Place, London NW1 OEU UK
Tel: +44
0
20 7380 8167 Fax: +44
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20 7874 1908 http://www.meters.anders.co.uk
For 9V operation it is recommended to power from a 9V
battery. The inputs are intended to float with respect to
the supply but if they do not float they must be no closer
than 1.5V from either VDD or VSS (VDD-1.5V and
VSS+1.5V)
see the circuits for non-floating inputs below.
CONNECTION DIAGRAM BASIC CONFIGURATION
APPLICATION CIRCUITS
To measure voltages greater than 200mV an
attenuator is required.
VIN=VD x R1+R2 VD max. is 199.99mV
EXAMPLES
VIN Display VDR1 R2
2V 1.999V 199.9mV 1MΩ110KΩ
10V 1500rpm 150mV 1MΩ15KΩ
R2
The input impedance becomes R1+R2. Choose accurate stable resistors.
Typically, R1=1MΩ. 9MΩ is a practical upper limit.
DC MULTI-RANGE VOLTAGE MEASUREMENT
DC CURRENT MEASUREMENT
Shunt resistance RS = Vs Ω
It is important to note the power
dissipation in the shunt and choose
resistor rating accordingly
PS= Vs = IIN RS Ω
EXAMPLES
22
IIN
IIN
Current RSPS
200mV 1Ω0.04W
2A 0.1Ω0.4W
DC MULTI-RANGE CURRENT MEASUREMENT
For multi-range, use, a 2 pole, 5
way rotary switch. 1 pole for
range select and the other to
connect the appropriate
decimal point to XBP
DC VOLTAGE RATIO MEASUREMENT
To determine the ratio between two
voltages apply the inputs as shown.
Displayed reading = V2 X 1000
Over range occurs when V2 > 2
Note Jumper J1 must be closed
V1
V1
To achieve a zero display reading
for a non-zero voltage input, apply
the offset voltage between C and
IL.
For a positive offset apply a
Positive signal to IL w.r.t. C.
Apply the input signal between IH
and C
Note jumper J1 must be open
DC VOLTAGE OFFSET
The OEM33 is designed for 5/9V supply. Incorrect supply
polarity will destroy the module immediately. It is ready
for general use when connected as in fig 1 for 5 volts.
For 9 volt supply the module may need calibrating before
use as follows. Connect as in fig. 2, apply 100mV to the
inputs from a calibrated source and adjust VR1 until the
display reads 1000.
The input range is 0-199.9mV . Over-range is indicated
by blanking the three least significant digits and
displaying a "1" in the most significant digit. If the input
voltage is reversed, a minus sign is displayed
automatically.
The module has 3 decimal points. D1, D2, D3 and 11
selectable annnunciators.
For 5V operation, IL must be connected to GD for
non-floating inputs (as fig. 1) and to the analogue
USER INSTRUCTIONS
Where a single 5V supply is not suitable
but you must connect your input signal
ground to the module supply ground
then either of the two non-floating input
circuits can be used. Note that the
module is set in 9V supply mode BUT
jumper J1 is left open.
NON FLOATING INPUTS (a) NON FLOATING INPUTS (b)Using the formulae choose resistors to
ensure the analogue inputs are no closer
than 1.5V from either VDD or VSS
(VDD-1.5V or VSS+1.5V)
For multi-range, use a 2 pole, 4
wa y rotary switch. 1 pole for
range select and the other to
connect the appropriate
decimal point to XBP.
DC VOLTAGE MEASUREMENT