Biphasic Stimulus Isolators


BSI-1A - Biphasic Stimulus Isolator


BSI-2A - Biphasic Stimulus Isolator

Characteristics BSI-1A

Output Waveform Follows Input (Linear)


Constant Current & Voltage Modes


Plus and Minus 125 Volts Compliance


Characteristics BSI-2A

Two Independent Constant Current Sources


Accepts TTL Or Biphasic Gates


Multi-Range 10-Turn Amplitude Controls


Description BSI-1A

The Model BSI-1A Biphasic Stimulus Isolator is totally battery powered utilizing optimum packaging design to provide maximum isolation of stimulus signals. This instrument is truly linear and will convert any waveform from 0 to plus and minus 10 volts into a constant current or constant voltage stimulus. It has a constant current range from ±100 nanoamps to ±10 milliamps with a compliance voltage of up to ± 125 volts and a constant voltage range between 0 and ±125 volts. A four-position front panel range switch allows optimum resolution for selecting precise stimulus amplitudes. A calibrated front panel control knob allows the investigator to apply input signal levels, which can then be attenuated to give continuously adjustable output levels. A separate output jack is provided for monitoring current levels through the electrode so that no connection need be made across the electrode, which could interrupt the stimulus current path.

The Model BSI-1A is a completely self-contained portable instrument with adjustable handle for convenient placement near the preparation. It is the logical companion to the BPG-1P Biphasic Pulse Generator.

For more detail please read the manual: Download Owners Manual

Description BSI-2A

The Model BSI-2A Biphasic Stimulus Isolator has been optimized for applications requiring precise control of rectangular waveform stimuli. It is designed for use with external timing circuits, which are biphasic single channel (e. g. MLS BPG-1P, Digital Controllers or other monophasic pulse signal sources such as computers). The external timing input(s) gates each of the two optically isolated, independently battery powered, constant current sources. Because they have completely independent isolators, range controls, and output circuits, the “A” and “B” outputs can be used as independent monophasic stimuli which are completely isolated from each other as well as from the control input. Each output has an inversion switch and an extra binding post to facilitate installation of coupling capacitors or current monitoring resistors. The two sets of output binding posts are strategically placed so that the addition of two jumpers (provided) converts the unit instantly to biphasic or pulse pair operation.

The Model BSI -2A features high compliance, high isolation, and the same conveniently portable plastic case as the BSI-1A. The main difference is that its output circuitry has been optimized for gated on-off operation rather than proportional input following. This mode of operation is inherently very low noise and eliminates the danger of applying DC currents as a result of low level offsets in the control signal between output pulses. It also permits manual fine-tuning of the output level from the unit itself, which can be placed near the preparation. If you need non- rectangular waveforms (e. g. sinusoids, ramps or computer D/A driving), we recommend the BSI-1A, a linear biphasic stimulus isolator with a complete range of both constant current and constant voltage output levels.

For more detail please read the manual: Download Owners Manual


BSI-1A - Biphasic Stimulus Isolator
Item Description
Constant Current ±100 nA to ±10 mA
Constant Voltage 0 to ±125 volts
Input Impedance 10 kOhms
Linearity 1% (input/output)
Noise <0.5% of full output range
Compliance Voltage in Constant Current Mode ±125 volts
Maximum Output Current in Constant Voltage Mode ±25 mA
Isolation Coupled through 1pF capacitor
Output to Ground Impedance 1011 ohms Shunted by 10 pf
Output Impedance <0.05 ohms for loads up to ± 10 ma
Input Voltage Range 0 to ±10 volts (will accept any waveform)
Range Adjust 4 position switch and calibrated input attenuator knob (0-1.0)
Rise Time 2 microseconds with 1 МΩ source impedance
Slew Rate 5 volts per microsecond
Current Monitor Output 1 mV/uA
Power Supply (4) 9 volt lithium batteries (Ultralife #U9VL), (life expectancy greater than 100 hours), (6) 3.6Volt C-cells
The BSI-1A is a linear output device and as such, it uses more current than pulse type output devices. The output amplifier stage draws 2.2 milliamps even when no signal is applied. This means that the high voltage batteries will operate for 81 hours continuously with no signal.
BSI-2A - Biphasic Stimulus Isolator
Item Description
Constant Current 100 nA to 10 mA each channel with polarity inversion switch.
Current Control Ranges 1, 10, 100 and 1000 uA per turn via 5 position rotary
Output Controls 10 turn potentiometer with indicating dial each channel.
Output Linearity 1% all ranges
Compliance Voltage 90 Volts each channel, independent batter sources.
Isolation 1,000 VDC (optically isolated) 30 pF between any two
Output Connections 3-way banana binding posts, 3 each channel.
Input Connections Floating BNC Jacks
Input Signal: A/B Biphasic ±2.8V min., TTL compatible, protected to ±15V
Input Signal: B Only ±2.8V min., TTL compatible, protected to ±15V
Power Supply 2: 9 Volt lithium batteries ULTRALIFE # U9VL. (replace with BAK BPL-l)
Battery Life 100 hours minimum
Package Bench mount with supporting handle, 3.5"H x 26"W x 7.5"D (less handle)
Weight 6Ibs (shipped with batteries installed)


Download Manual

File name: BSI-1A Owners-Manual.pdf

Download Manual

File name: BSI-2A Owners-Manual.pdf

Other Microprobes equipment used with BSI-1a & BSI-2a
Download Manual

File name: BPG-1P Owners-Manual.pdf

Request a quote Close me
Please let us know your name.
Please type your Institution name.
Please let us know your email address.


Please let us know your message.
Please complete the security check.


All Microprobes for Life Science products are warranted against defects in materials and workmanship for one full year from the date of delivery. Products that prove to be defective during the warranty period will be repaired or replaced without charge provided they are returned to the factory. No other warranty is expressed or implied. We are not liable for consequential damages.