Bipolar Constant Current Isolated Stimulator (DS4)

Bipolar Constant Current Isolated Stimulator (DS4)

The DS4 provides an isolated biphasic constant current stimulus in response to an external command voltage signal. Generally speaking, the command signal is a computer generated DAC signal via software. The DS4 accepts a variety of voltage input ranges from ±1V to ±10V and produces a constant current output in 4 overlapping ranges from ±10_A to ±10mA. The compliance voltage is ±48V. In addition, the DS4's GATE input allows multiple DS4's to be connected to a single analog voltage source, with each DS4 capable of being independently enabled.

  • No interference with recordings
  • No ground loops
  • Bi-phasic constant current
  • Gated operation allows multiple units
  • Battery powered energy saver circuitry
  • Compatible with electrophysiology recording

 

Item# Description U.S. List Price Quantity
65-0364 (DS4) Biphasic Stimulus Isolator
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One problem with stimulators that use an external voltage source to define the stimulus waveform is that small offsets or noisy baseline signals from the DAC's can result in battery drain or low amplitude stimulation. The DS4 uses a special inactivity sensor to monitor the input voltage and disable the output if this voltage falls within 0.2% of the full scale value for a user selectable time period. This inactivity sensor reduces battery usage and damaging leak currents during infrequent stimulation, while at the same time maintaining low zero crossing distortion for repetitive waveforms.

The DS4 uses an external power supply to power the input control circuitry and inexpensive batteries to provide an opto-isolated voltage source.

Specifications
Output Biphasic constant current proportional to the input voltage
Output Ranges ±10_A; ±100_A; ±1mA; ±10mA for a full scale input
Output Duration >2_s
Compliance ±48 V from 8x GP23A batteries
Linearity ±3% of full scale output for each output range
Output Impedance >900Mohms
Output Rise Time <5_s (1kohm load), <40_s (1Mohm load)
Frequency Response Expected DS4 output is maintained for frequencies up to 5kHz.
Inputs
IN
Ranges
±1; ±2.5; ±5; ±10 V full scale (selected by an internal jumper) with a limit of ±12V max without damage
Input Impedance 1 Mohm
GATE Range: TTL; Gate OFF if Low; Gate ON if High or open circuit. Limit of ±15V max. Input Impedance: 10kohm
Inactivity Sensor The output is disabled if the voltage input remains within 0±0.2% of the full scale value for a user selectable period of 100ms, 200ms, 1s or 2s. This time period can be adjusted with an internal jumper.
Connections Output - 2mm shrouded, touch-proof sockets (red and black) spaced at 0.75" Input - Front panel BNC socket Gate - Front panel BNC socket Battery Test - Six 2mm sockets Power - Socket for external power supply
Controls: Gate - On/Off toggle (off overrides BNC input) Output Range - 4 position rotary switch Power - On/Off toggle switch
Indicators Power ON - LED Green (lit when the power supply is connected and DS4 is switched On) Gate Enabled - LED Amber (lit when Gate is On and the Gate Input is held TTL high) Phase+ve - LED Amber (lit when input exceeds +0.2% of full scale voltage) Phase-ve - LED Amber (lit when input exceeds -0.2% of full scale voltage)
Power Included external power supply (input voltage 110V - 220V) providing ±15V DC output 10 x 12V GP23A Batteries.
Mounting One or two stimulators may be mounted in a 19" rack using a specially fabricated frame (D121-11)
Dimensions
(W x H x D)
190 x 110 x 80 mm (7.5 x 4.3 x 3.1 in)
Weight (approx.) 500 g (1.1 lb)