Multichannel Systems MC_Rack Manual User Manual
Page 90
MC_Rack Manual
84
Amplifier gain
Specify the gain of the amplifier used. The gain is an intrinsic option of the device and can not be
altered. Make sure to use the gain the device actually has. Otherwise the recorded data will have
wrong voltage values. The default amplifier gain of a MEA1060 amplifier is 1200. For MEA2100-
Systems the amplifier gain is automatically set depending on the hardware. Any value between
1 and 1,000,000,000 is valid. The original signal is calculated automatically from the input and the
amplifier gain.
Important: The gain is a hardware property. You cannot change the gain of the amplifier with
MC_Rack. Make sure you use the gain that the amplifier actually has. This is especially important
if you use a PGA amplifier with programmable gain. Use the PGA-Control program to change the
PGA's gain and make sure you specify the same gain in the MC_Rack program as well. Otherwise,
the recorded data will have wrong voltage values.
Click Enter... to change the amplifier gain settings.
Input voltage range of data acquisition board
You can adjust the input voltage range of the MC_Card from +/- 400 mV to +/- 4 V with the
software control in the MC_Rack program. The lower the input voltage range, the higher is the
voltage resolution. You need a higher input voltage range if your biological sample generates
higher voltages, for example, cardiac signals from whole-heart preparations, and / or if the
amplifier gain is higher, so that the amplified output signal amplitude is higher, too. For spike
data, an input range of -819 to +819 mV will in most cases be fine, whereas for sum field
potentials like LTP that can be in the range of mV, you will probably need a higher input range.
For example, if you have a standard MEA amplifier with a gain of 1200, and choose a MC_Card
input voltage range of 819 to +819 mV, this results in a signal input range of -682 to +682 μV.
With a MC_Card with 14-bit resolution and an input voltage range of -819 to +819 mV, the
voltage resolution of the MC_Card will be 0.1 mV or 100 μV: A 14 bit resolution means 2
14
= 16384
available voltage values. 819 mV * 2 = 1638 mV total input voltage range / 16384 = 0.1 mV. For
a standard MEA amplifier with a gain of 1200, this means a resolution of 83 nV for the recorded
original signal.
Select the desired input voltage range from the Input Voltage Range of Data Acquisition
Board list.