Kation Scientific ExAmp-20K User Manual - page 2
Carbostar-4LT
Recording/iontophoresis
microelectrode
Adapter
No. 2331
Ground
socket
In order to minimize external noise pickup and interference, experimental set-ups have to be correctly shielded and grounded. Overall
shielding is often provided by a Faraday cage. Faraday cages do not necessarily remove interference from magnetic fields which
usually cause the most problems. Here we provide a few tips to improve quality of recordings.
Tip 1. Place the the preparation to be recorded as close to a large carbon steel (not stainless steel!) baseplate as possible (which should
be connected to the ground pin of the headstage probe). The greater the mass of the plate, the more helpful it will be at deflecting a
magnetic field. A steel slab 1/2" (12 mm) thick and at least 20" (500 mm) on each side greatly improves the quality of extracellular
recordings.
Tip 2. Always keep the lead wire from the electrode to the headstage probe as short as possible, less then 2" (5 cm).
This is
accomplished by our unique headstage probe design so that microelectrodes can actually be plugged straight into the probe.
Tip 3. Keep line-powered equipments as far away from the site of recording as it is possible. Everything near the preparation should
be grounded to a single point, that is the ground pin on the headstage probe and to nothing else. Use of a "star formation” grounding
will minimize ground loops.
Tip 4. Isolation of extracellular amplifiers from power line ground prevents ground loop formation.
Certification:
Kation Scientific certifies that this instrument has been tested and inspected thoroughly and was found to meet all published
specifications before shipment from the factory.
Warranty:
This product is warranted against defects in materials and workmanship for one full year from the date of shipment as long as it has
been exposed to normal and proper use. Products which prove to be defective during the warranty period will be repaired or replaced
without charge provided they are returned to the factory. Kation Scientific will provide for servicing and calibration after the warranty
period for a reasonable service charge. The instrument should be shipped to the factory postage prepaid.
Performing an experiment
Electrode holder adapters
Adapter No. 2331 is used for attaching Kation-made single- or multibarreled carbon fiber electrodes to
the headstage. In order to configure this type of electrode holder, screw the adapter onto the headstage
and simply plug the electrode's connector pin in as shown above. Adapter No. 2332 is used to
accomodate long, small-diameter metal (tungsten or stainless steel) electrodes. To configure this type
of electrode holder, first insert the electrode pin-first into the front of the adapter and pull it through so
that it protrudes somewhat from the back end of the adapter. Use a small tweezers to grasp the pin of
the electrode and insert it into the input socket of the probe. Screw the adapter onto the probe gently by
hand. Finally, use an inch-long strip of metal or electrical tape to fix the electrode as shown in the right
figure.
For other type of electrode holder adapters check our website.
Grounding
Circuits of the headstage probe and main amplifier are galvanically isolated from the input DC power
(floating configuration). In many cases, however,
a better recording quality may be achieved by
connecting the amplifier’s ground (Gnd) to the input DC ground (Case)
. This solution may be
counterproductive in other instances.
The headstage probe has two miniature sockets for grounding: one on the front end (shown above) and
one on the rear end. Use one of them to ground the amplifier to your preparation. All other instruments
should also be connected to this point to achieve a “star formation” grounding.
After following these basic rules, the removal of interference noise is normally a process of trial and error, involving experiments
with slightly different patterns of grounding. Remember that our ExAmp-20K amplifier permits a very smooth, low-noise recording.
Thus, if your extracellular recording shows a frustrating level of noise keep trying to find and eliminate the source.
See also the ‘Grounding’ section below.
No. 2332
Kation Scientific, LLC, P.O. Box 14674, Minneapolis, MN 55414 Phone/Fax: (651) 698-5167.
E-mail: info@kationscientific.com Web site: www.kationscientific.com