Axon MultiClamp 700A User Manual

Reference Section • 105
Chapter 5
Model Cell
• PATCH-1U model cell is a standard accessory provided with the MultiClamp
700A. It is useful for setting up, testing and doing the tutorials described in
Chapter 3.
The model cell is a small metal box with three connectors labeled BATH, CELL and
PATCH, and an unlabeled 2 mm gold plug which connects to the 1 mm grounding
plug on the rear of the CV-7A headstage. The circuit is shown in Figure 4.15 (right).
A 10 M resistor models the electrode, the cell is modeled by 500 M in parallel with
33 pF (the membrane time constant is 16.5 ms), and a 10 G resistor models the patch.
The pipette capacitance is about 4-6 pF. The charging time constant is approximately
330 µs (10 M x 33 pF).
The PATCH-1U model cell has been made without a switch to change the model
between the BATH, PATCH and CELL positions. This is because even the best
switches have an enormous amount of leakage resistance and capacitance that
increases the noise three to five times beyond what can be achieved with a good seal.
Instead of switches, three separate plug positions have been provided and you can
rotate the model cell into the position required. With this technique the noise
contribution of the model cell is still somewhat more than can be achieved with a good
seal, but the increase is less than 50%.

Axon MultiClamp 700A Specifications

General

Brand	Axon
Model	MultiClamp 700A
Category	Amplifier
Language	English