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OT-BridgeAmp4
4 Channels General
Purpose Amplifier
User Manual v1.0
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OT-BRIDGEAMP4 User manual v 1.0
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INDEX
1. GENERAL FEATURES ....................................................................... pag. 3
1.1. GENERAL DESCRIPTION
.............................................. pag. 3
1.2. TECHNICAL SPECIFICATION
......................................... pag. 3
2. DETAILED DESCRIPTION ............................................................. pag. 4
2.1. FRONT PANEL
................................................................. pag. 4
Single Ended INPUT ............................................................ pag. 5
Differential Single Ended INPUT .......................................... pag. 5
INPUT selector ................................................................... pag. 5
OFFSET switch ................................................................... pag. 5
Output BNC ........................................................................ pag. 5
OFFSET compensation potentiometer .................................. pag. 5
HIGH PASS FILTER selector ................................................ pag. 6
GAIN selector ..................................................................... pag. 6
LOW PASS FILTER selector ................................................. pag. 6
2.2. BACK PANEL
.................................................................... pag. 7
Power supply socket ........................................................... pag. 7
Power supply switch ........................................................... pag. 7
Fuse box ............................................................................ pag. 8
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1. GENERAL FEATURES
1.1. GENERAL DESCRIPTION
The OT-BRIDGEAMP4 is a four channel general purpose amplifier. It can amplify and
filters any referenced single ended or differential single ended signal. The four channels
are completely independent and can be used simultaneously.
1.1. TECHNICAL SPECIFICATION
The OT-BRIDGEAMP4 is a programmable amplifier with selectable high pass filter, low
pass filter, gain and offset compensation. The OT-BRIDGEAMP4 technical specifications
are reported in Table 1.
DC coupled
Selectable High pass filter
1 Hz (II order)
10 Hz (II order)
100 Hz (II order)
Selectable Low pass filter
10 Hz (VIII order)
100 Hz (VIII order)
200 Hz (VIII order)
500 Hz (VIII order)
Selectable Gains
100, 200, 500, 1000, 2000, 5000 V/V
Gain error
< 5 %
Input resistance
> 1012
Input range
4 V
Output range
5 V
Output offset
< 5 mV
Offset compensation
3 V, when DC coupled
TAB. 1: Amplifier technical specification
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2. DETAILED DESCRIPTION
2.1. FRONT PANEL
Figure 1 shows connectors switches and selectors of the OT-BRIDGEAMP4. The four
channels are separated by vertical lines.
Any indication reported in the following description can be associated to any OT-
BRIDGEAMP4 channel.
FIG. 1: Detail of OT-BRIDGEAMP4 front panel reporting a channel
Single ended
INPUT
Output BNC
OFFSET
switch
INPUT
selector
Gain selector
Low pass filter
selector
High pass
filter selector
OFFSET
compensation
potentiometer
Differential
Single ended
INPUT
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Single Ended INPUT
This connector is the input for the corresponding single ended signal.
Differential Single Ended INPUT
This connector is the input for the corresponding differential single ended signal.
INPUT selector
This selector can be used to select the amplifier input. When the switch is in the S.E.
position the signal present at the BNC single ended input is the input for the
corresponding amplifier channel. When the switch is in the Bridge position the signal
present at the differential single ended input is the input for the corresponding amplifier
channel. When the switch is in the NONE position the input of the corresponding amplifier
channel is connected to ground. The INPUT selector can be used to turn off the input and
evaluate the offset amount introduced by the internal offset compensation at the amplifier
channel output.
OFFSET switch
When the channel is DC coupled the offset compensation can be turned on or off using
this switch. Note that this switch has no effects when the high pass filter is used.
Output BNC
This connector is the output for the corresponding amplifier channel.
OFFSET compensation potentiometer
This multi-turn potentiometer controls the offset compensation. To activate the offset
compensation the channel have to be DC coupled (refer to LOW PASS FILTER selector)
and the OFFSET switch have to be placed in the ON position.
Note that the offset is multiplied by the gain selected and the potentiometer sensitivity
increase with the gain.
The offset value, introduced by the offset compensation circuit, can be sent to the output
BNC and measured. The input signal has to be excluded by positioning the INPUT selector
in the NONE position and the channel gain has to be set equal to 100. The measured
offset value will be 100 time the real offset introduced by the system.
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HIGH PASS FILTER selector
This four positions selector allows to select the -3 dB corner frequency of the second order
high pass filter. The DC position indicates that no high pass filters are introduced and the
channel is DC coupled. Available frequencies are: 1 Hz, 10 Hz and 100 Hz.
The frequency values are theoretical, refer to the “Modulo di collaudo” for the real values.
GAIN selector
This six positions selector allows to select the channel gain. Available gains are: 100, 200,
500, 1000, 2000, 5000.
The gain values are theoretical, refer to the “Modulo di collaudo” for the real values.
LOW PASS FILTER selector
This four positions selector allows to select the -3 dB corner frequency of the eighth order
low pass filter. Available frequencies are: 10 Hz, 100 Hz, 200 Hz and 500 Hz.
The frequency values are theoretical, refer to the “Modulo di collaudo” for the real values.
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2.2. BACK PANEL
Figure 2 shows the OT-BRIDGEAMP4 back panel.
Power supply socket
On the back panel, the Power supply socket can be found. It is used for the connection of the
power supply cable. The OT-BRIDGEAMP4 system can be supplied with a supply voltage
ranging from 90 to 260 VAC, 50÷60 Hz; it is very important that the supply cable includes
the earth connector.
DANGER: The use of extension cords or multiple sockets or adaptors can affect the performance of the
instrumentation. The connection to sockets without earth connection or with a low quality earth
connection can affect the performance of the instrumentation and cause potential harm to operators.
Power supply switch
On the back panel, together with the power supply connector, the power supply switch can be
found. To switch the OT-BRIDGEAMP4 on, move the power supply switch to position 1; to switch it
off, move it again to position 0. For higher safety, the switch interrupts connection to both power
conductors. When the system is not used, this switch should be off.
0 1
Power supply
socket
Fuse box
Power supply
switch
FIG. 2: Back panel of OT-BRIDGEAMP4
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Fuse box
On the back panel, together with the power supply connector, a box containing the two
power supply fuses (one for each cable) can be found. In normal working conditions the
two supply fuses must not be interrupted; the interruption of connection in either of them
can occur only when the system is damaged; this means that the device could no longer
be in compliance with the security standards, even if the fuses have been replaced
correctly.
DANGER: In case of interruption of one or both fuses, do not replace them by yourself, but immediately
contact the Technical Assistance Service of Ottino Bioelettronca.
Besides, replacing the fuses with others of different type can be dangerous. Always remove the power
cable before testing the fuses.
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Produced and distributed by:
OT Bioelettronica
C.so Unione Sovietica 312
10135 – Torino - ITALY
Tel: +39.011.6198498
Fax: +39.011.6198498
URL: www.otbioelettronica.it
e-mail: e.merlo@otbioelettronica.it, a.bottin@otbioelettronica.it
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