HEKA Elektronik EPC 10 USB, Hardware Manual, Page: 27 / 81

4.1 Testing the EPC 10 USB with the Model Circuit 21
The steps listed above can be automatically executed by clicking on the SEAL button or pressing the key ”2” on
the numerical keypad ( Amplifier Window has to be active). This will execute the following predefined protocol lines
that increases the gain and then performs twice an auto-compensation - considering a possible failure in the first
attempt.
2 : SEAL
E Mode 3 ; Whole Cell
E Gain 12 ; 20 mV/pA
E AutoCFast ;
E AutoCFast ;
E Beep ;
4.1.4 ”Whole-Cell” - Voltage Clamp Recording
After compensating C-fast well, you can now switch into the ”0.5 GΩ” position of the model circuit. This will
simulate a ”model cell” with 22 pF ”membrane capacitance”, 500 M Ω ”membrane resistance” and 5 . 1 M Ω ”input
resistance” in the whole-cell configuration. This mode can be used to verify the C-slow controls, the action of series
resistance compensation with C-slow enabled, and the current clamp mode (see below).
Figure 4.5: Before C-slow compensation
After reducing the gain to 20 mV/pA (1), the R-memb field should reflect the changed ”membrane” resistance
and display a value close to 500 M Ω (2). You should see in the Oscilloscope three capacitive transients (black line)
caused by the 22 pF capacitor in the model circuit. The ”slower” time constant of the model cell - compared to
the ”fast” time constant from the middle position - is
τ = R
s
∗
C
m
= 5 . 1 M Ω
∗
22 pF = 112 µs
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