Stimulate different sites with 1ms switching times
The D188 Remote Electrode Selector and the new D189 Low Voltage Electrode Selector allow you to direct an electrical stimulus of up to 1A from a single stimulator to one of up to eight pairs of electrodes. The D188 is intended for applications where the stimulator voltage might exceed 100V (e.g. DS5, DS7A, DSAH, DS7R or DS8R), while the D189 is intended for use with stimulators that do not generate more than 100V (e.g. DS2A, DS3, DS4).
Both the D188 and D189 are supplied with “virtual front panel” software compatible with WindowsTM 7 and higher, which permits manual switching between stimulation sites via a key-press or mouse click. However, the remote electrode selectors were predominantly designed for situations where stimulation delivery needs to be rapidly switched between sites under remote, digital control. With switching times of 1ms, the D188 and D189 Electrode Selectors can be used for demanding stimulation applications involving multi-location stimulation in studies of pain, cognitive behaviour or sensory perception. An example of a typical stimulation system incorporating the D188 is given in the diagram below.
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- Remote Electrode Selector.
- Power Supply with adaptor plates for European, North American and UK plugs.
- USB Cable, 2m long.
- Digital Communication Cable (15-way “D” to bare wires), 1m long (D188-08).
- Virtual Front Panel Software, supplied on USB stick.
- Operator’s Manual
Digitimer only develops for the Windows environment, so unless you are able to run a Windows emulation, we would suggest that you configure the settings of the D188 using a Windows PC. As the settings are persistent, the D188 can then be controlled with digital inputs from a data acquisition interface rather than via the USB connection.
It is important to appreciate that the electrode switching process is not instantaneous. It takes several hundred microseconds for the D188 to switch channels in response to a change in the TTL state of the digital inputs. We recommend that stimulus delivery and digital switching protocols are devised which allow for at least a 1ms pause in stimulation following a digital input state change. If this pause is not adhered to, stimulation may occur in multiple channels during the 1ms transition period.
The D188 accepts standard TTL logic pulses which can be provided by an array of commercially available data acquistion/control hardware. Products from Cambridge Electronic Design, National Instruments, Labjack and many others have all been used to control the D188 for a variety of applications including psychological testing and pain scoring.
In order to use more than one D188 and a single stimulator, it will be necessary for the user to connect the stimulus source, in parallel, to the COM inputs of each D188. In this case, our D185-HB1 output adaptor cable would be a suitable alternative to our D185-HB4. Alternatively, the stimulus source can be connected to a single D188 and one output channel of that unit used to pass the stimulus to a second D188. In this way, multiple D188’s can be “daisy chained” to one stimulator.