HEKA Elektronik EPC 10 USB, Hardware Manual, Page: 23 / 81

4. Verifying and Testing the EPC 10 USB
4.1 Testing the EPC 10 USB with the Model Circuit
The following tutorial will guide you through most of the basic and some of the unique and more sophisticated
features of the
EPC 10 USB
amplifier. At the same time it allows you to check, whether the amplifier is
functioning properly. You can use the model circuit you got together with the amplifier as a substitute for a
real patch clamp recording and explore the virtual ”front panel” of the
EPC 10 USB
supplied in the acquisition
software (
Patchmaster
)
4.1.1 The Model Circuit
The model circuit connects to the probe input via a BNC adapter and the plug goes to the black GND connector
on the probe:
The model circuit provides a switch with three positions simulating the following conditions typically observed
during an electrophysiological experiment:
ˆ
In the top position an ”open” pipette with a resistance of 10 M Ω is simulated. This mode is useful for
applying a test pulse and for correcting offset potentials.
ˆ
The middle position simulates a pipette attached to the cell membrane after the GΩ seal formation. In this
setting only a capacitance of 6 pF is left over, corresponding to the ”fast” capacitance of a pipette sealed to
the cell membrane. This mode allows you to test the C-fast compensation.
ˆ
In the bottom position a ”model cell” in the whole cell patch clamp configuration is simulated. The ”input
resistance” is 5
. 1 M Ω, the ”membrane resistance” is 500 M Ω and the ”membrane capacitance” is
∼
22 pF.
This mode allows testing the C-slow compensation and the current clamp mode. Furthermore it is useful to
check stimulation patterns you design within the acquisition software.
Note: This model cell has a long ”membrane” time constant (about 10 ms).
The following tutorial can be best executed with
Patchmaster
.
4.1.2 ”SETUP” - Applying the Test Pulse
First, connect the model circuit to the probe input via a BNC adapter and plug the black cable to the black
ground connector of the probe. If
Patchmaster
is not running yet, start the program which is located in the
Patchmaster
folder inside the HEKA folder. MS Window users might alternatively use the Start button to
launch
Patchmaster
from Programs
→
HEKA. Press the SPACE key to bring up the so called ”virtual front
panel” ( Amplifier Window ). It provides a graphical representation of the
EPC 10 USB
amplifier. The panel lets
Figure 4.1: Model Circuit