Model BPG-1

• AUTOMATICALLY TIMED AND BALANCED BIPHASIC PULSES
• INTERNAL TRAIN FREQUENCY GENERATOR, EXTERNALLY GATED
• PRECISION 0- +/-10 V OUTPUT LEVELS
• 5-DECADE POST-TRIGGER DELAY
• 5-DECADE INTER-PHASE DELAY

• Also available with independent phase shape controls:

BPG-2: Identical to BPG- 1 except for additional set of control knobs: 10 turn amplitude and 5~ec* duration controls for second phase instead of duplicating first phase values. Comes in -a width module 8.4~' wide. Same timing and polarity controls as BPG-l.

• For a complete stimulus control and delivery system, use BAK DC-1 Digital Controllers or BAK TM-1 Timing Module in front of BPG-l ,2 Pulse Generators and follow with BSI-1 Biphasic Stimulus Isolators for flexible, safe, precise constant current or voltage delivery

The importance of using balanced cathodiclanodic biphasic waveforms was discussed by Dr. J.C. Lilly and colleagues* in 1955 and has since been accepted as the best way to avoid tissue damage and metal electrode electrolysis. The BPG stimulators are specifically designed to facilitate generation and control of this waveform without requiring multiple timing generators, external configuration or complicated calculafions. However, they also function well as simple generators of monophasic pulses and pulse trains. The inter-phase interval control is particularly useful for generating trains of monophasic pulse pairs (see Options below) with variable interval as is frequently required for refractory period determinations.

Waveform Control:

The unique aspect of the BPG series is that the second phase timing always starts at the end of the first phase regardless of first phase dura-tion. This means that the phases can never overlap and that a desired interphase interval does not have to be calculated or reset as pulse width is changed. The BPG-1 further guaran-tees perfect waveform symmetry by setting the width and amplitude of both phases from a single set of controls.
 
 
 
 
 
 
 
 
 
 
 
 
 

* Lilly, J.C. et al. "Production & avoidance of injury to brain tissue by electrical current at threshold values" , Electroenceph. din. neurophysiol. 7:458-9 (1955)
Lilly et al, "Brief, noninjurious electric waveform for stimulation of the brain", Science, 121:468
(1955)

The BP(3-1 and 2 Biphasic Pulse Generators are designed for both stand-alone manual operation and electronic interface with computers and timing sequence generators such as the BAK DC-1 Digital Controller or BAK TM-1 Timing Module. The selected output waveform (as described under Waveform Control) may be delivered as either single presentations following a manual or electronic TRIGger pulse. Alternatively, a train of these waveforms at a settable clock rate may be OUTPUT for the duration of a manual or electronic GATE input, as shown under Waveform Control.

All of the timing controls operate with single turn pots for one decade of continuously variable settings selected by a 4 or 5 decade multiplier range switch. This is designed to give a reasonable degree of precision resetability without being awkward to use when large ranges of these parameters must be quickly and smoothly scanned. Parameters such as DELAY (post-trigger) and INTERVAL (between phases) have zeroing switches built into their continuous controls. The train output rate is indicated as true frequency in pulses per second rather than inter-pulse interval time. The multi-range structure for all timing parameters makes the instrument equally convenient and accurate for time frames from 10 microseconds to 100 msec. To facilitate monitoring of the BPG output state by computers, oscilloscopes or other equipment, a SYNC output is provided which puts out a standard, brief TTL pulse at the output time of each phase of actual output.

The amplitude control(s), unlike the timing controls, are designed to optimize precision setting and grading of output level over a single 0- +/-10V range. A 10-turn linear pot and dial are provided along with a polarity inversion switch. Range setting is generally provided by the stimulus isolator and/or constant current driver such as the BAK BSI-l Biphasic Stimulus Isolator.

The Model BPG-l Biphasic Pulse Generator is of modular design and receives its power from the Model RP-1 rack mount power supply module cage system.

TM-1 Timing Module
DC-1 Digital Controller
BSI-1,2  Biphasic Stimulus Isolator (constant current/voltage source)
MDA-1 ,4 Amplifiers with stimulus delivery relays, manual and electronic gating
A-1, 1B, 2 Amplifiers with stimulus delivery relays, manually operated