This unit provides two channels of high power, constant current stimuli needed for punctate or field stimulation of preparations in low impedance baths. The fully protected unit provides control of stimulus strength up to 500mA from 100V into low impedance baths with impedances as high as 200 ohms.
The output current of each channel is independently controlled by a single turn control and range selector switch. Each channel has an on/off switch, stimulus indicator and an overload/out-of-compliance indicator.
The control and timing for the pulses is generated by selecting other modules from the D330 MultiStim range.
System – Over protection & indication
Even though each D343 channel can supply up to 500mA, the D337 rack is only specified for supplying an aggregate stimulating current of almost 1A continuously. The system is designed to supply short 500mA stimulus pulses from all channels but if the pulses are too long the green ‘Power’ LED on the left hand module will turn red as a warning. If this is not heeded and the demands of the system are not reduced, there is an over-current power cutout fitted to the rear of the rack that will trip.
Module – Overload protection, Out-of-Compliance detection & indication
- If the power dissipation of the module is exceeded the red overload LED will illuminate and the output will be inhibited for both channels until the unit has cooled when it will be automatically reset.
- If the impedance of the preparation is too high for a channel to supply the set current through it, the red overload LED will illuminate momentarily, as a warning of an ‘out-of-compliance’ condition. This will also warn of an open circuit stimulating lead.
Current and Voltage monitoring
The current and output voltage of each channel can be monitored independently with the D335 Meter. This can show either the voltage or current of the selected channel immediately before the end of the stimulation pulse.
– for constant voltage stimulation up to 100V at 1A, see D333H Dual Stimulator