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GENERAL INFORMATION
Axopatch 200B, Copyright 1997-1999, Axon Instruments, Inc.
Power-Supply Glitches
The Axopatch 200B has been designed to minimize the effects of power-supply transients
(glitches). Some power-supply glitches do, however, get through. These can cause
transients to appear on the voltage and current outputs which may corrupt high-sensitivity
recordings.
The only completely effective way to gain immunity from mains glitches is to eliminate
them at the source. Most glitches are due to the switching on and off of other equipment
and lights on the same power-supply circuit. Precautions to be taken include:
1) Avoid switching equipment and lights on or off while recordings are being made.
2) Water baths, heaters, coolers, etc. should operate from zero-crossing relays.
3) RFI
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filters should be installed in glitch-producing equipment.
In most circumstances, occasional transients on the outputs are inconsequential and,
therefore, no precautions have to be taken.
Ten-Turn Potentiometers
The ten-turn potentiometers used in the Axopatch 200B are high-quality wirewound types.
An inherent problem of wirewound potentiometers is that the wire elements tend to oxidize.
When this happens, significant instrument noise becomes noticeable when the
potentiometer is turned. This condition is easily cured. If noise is observed when a
potentiometer is turned, the potentiometer manufacturer recommends to rapidly spin the
knob 20-30 times between full clockwise and full counterclockwise. This clears the oxide
off the element and restores noise-free operation.
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RFI - Radio Frequency Interference
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