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Electrical Pulse Generator


The stimulator consists of a grey electrical box whose front panel features a variety of dials, switches, lights, and electrical terminals. Features are color coded and extensively labeled. Researchers have marked various settings in permanent maker and tape. Both sides have cut out handles. The rear panel features vents, electrical terminals, fuses, and a power cord. A retractable bar on the bottom can be used to incline the unit towards the operator.

An extensive manual is provided with the instrument. The manual contains a copy of an experimental setup involving the instrument (see image 5).

Accession Number: 2012.ihpst.11

Alternative Name:

Model S88 Multifunction Solid-State Square Wave Stimulator

Primary Materials: Steel, Aluminum


Front Panel: “Grass S88 Stimulator”, “Grass Medical Instruments, Quincy, Mass., U.S.A. Since 1935”, “MAXIMUM PATIENT CURRENT 150 MA DC WITH 1000 OHM LOAD”, “Serial 742T8C”; Back Panel: “Grass Instrument Co./ Quincy, MA. USA/ Mod. S88B Date 4-77”

Dimensions (cm):

Height = 23.5, Width = 43.5, Length = 21.5


Provides an adjustable electrical impulse for various research purposes.

Condition: Excellent: Minor scuffs and abrasions.

Associated Instruments:

Manufacturer: Grass Instrument Co., Quincy, MA.

Date of Manufacture: April 1977


This instrument was purchased by the U of T Eye Department (Department of Ophthalmology and Vision Sciences). It was in use at Toronto General Hospital, from the late ’70s until the mid ’90s.On 13 February 2012 it was donated to the IHPST by Dr. John Alexander Parker, Professor emeritus of Ophthalmology at the University of Toronto Faculty of Medicine.

Additional Information and References:

Historical Notes:

This Grass S88 Stimulator was used to control optical stimulus in experiments as well as to synchronize other apparatus.
Some of these experiments studied the eye by producing electroretinagrams (ERGs.) In this case, the instrument was used to produce a controlled visual flash stimulus. The electrical activity of eye receiving this stimulus would be recorded on an ERG (see image 5).
This stand-alone instrument was ultimately replaced by a computer controlled system.

1) The <a href=””>company website</a> lists the current version of this instrument.


  • Donated to UTSIC