DS5 Isolated Bipolar Constant Current Stimulator DS5 Operator's Manual 5.0
Applying a Stimulation Protocol
Introduction
All appropriate input and output connections should now have been made to the DS5, including connections
to a dummy load or patient. The voltage source should be connected to the DS5 voltage input socket, but
should not be delivering a stimulus waveform. The DS5 should have been powered ON for at least one hour
prior to use in order to equilibrate temperature sensitive components. Whether the operator is preparing to
stimulate a patient or a “dummy load” it is necessary to Autozero the DS5 prior to enabling the stimulator
output. Both of these steps are detailed below.
The Autozero Function
The autozero function is used to ensure that the baseline input voltage is translated into zero current at the
output even if there is a small DC offset present at the input. Autozeroing should be carried out by pressing
the F2/AZ key once an external voltage source has been connected to the DS5, but BEFORE any stimulation
voltage is applied to this input. The autozeroing procedure is prompted by the appearance of the autozero
timeout icon in the F2 zone of the display upon startup, during use and whenever the output has been
disabled.
If the stimulator does not autozero when the F2/AZ key is pressed, a warning beep will sound and an icon
will be displayed in the F2 zone indicating the reason why the autozero could not be completed. If the
autozero fails, please refer to Table 3.1 for an explanation of the displayed icon. Once autozeroed, the
output can be enabled and a stimulation protocol can proceed.
If the output remains enabled for a 5 minute period, then the flashing autozero timeout icon re-apppears in
the F2 zone of the display, prompting the operator to autozero the unit once again. If the operator fails to
press the F2/AZ key, the DS5 will remain enabled until the user disables the output manually or it is disabled
automatically due to an error or an output limit being exceeded. In this way, stimulation protocols can be
completed without interruption, however, we do recommend that the DS5 is autozeroed regularly so as to
minimise the chance of the low level (baseline) current safety limit being exceeded during a study. If the
stimulator output is disabled either manually or automatically while the autozero timeout icon is displayed, it
will not be possible to re-enable the output until the stimulator is autozeroed.
Enabling & Disabling the Stimulator Output
On the right hand side of the DS5 front panel, an orange momentary action toggle switch allows the
operator to enable or disable the stimulator output. The stimulator will not pass a stimulus to a subject until
it is enabled and this can only be accomplished if there are no warning icons displayed that require user
intervention. For example, it will not be possible to enable the output if the DS5 requires autozeroing, or if a
voltage has been detected at the voltage input socket. A warning icon will be dispayed in the F4 zone to
indicate the reason why the output remains disabled. Once enabled, it is possible for the external voltage
source to control the output of the stimulator.
Enabling Upon Startup
To enable the stimulator the orange toggle switch needs to be pushed transiently upwards (it will
automatically return to the central position). The unit should give an audible confirmation beep and the
output enabled icon should be displayed in the F4 zone of the display. The output can be disabled at
any time by transiently pushing the orange toggle switch downwards, stimulation will cease and the output
enabled icon will disappear from the display. We would suggest that the operator routinely disables the
Digitimer Ltd. 32 of 52 Copyright © 2009
To Next Page
Loading...