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Transistor Analyzer


This instrument is contained in a black suit-case sized case with a plastic handle, metal corner protectors and two metal latches that are released by sliding a metal strip at the side of each latch. The lid is designed to be removable when the case is opened.

The instrument is fixed inside the bottom of the case, with two open storage areas at the top of the box and the control panel occupying the remaining lower portion of the box. In the storage areas, there is a power cable, a couple of electrical wires, some other metal pieces, a ‘caution’ label, and an unopened plastic bag containing two keys.

On the panel there are three indicator dials. The left one is labeled “INPUT CURRENT” the right “COLLECTOR CURRENT” and the central one “INPUT VOLTS COLLECTOR VOLTS REACH THRU”. Above this centre dial there is a copper panel with various electrical connectors affixed. Each of these can be screwed down to hold a wire in place.

There are a number of knobs, dials and switches across the panel. The two largest knobs are labeled “INPUT” and “COLLECTOR”, and there are graduations drawn directly on the panel surface to indicate. A white arrow on each knob acts as a pointer. There are five tear-drop shaped knobs on the surface, and three large switches with plastic ends. There is one small toggle switch for turning the instrument on and off, with an red indicator light above it. There is also a small button that can be depressed and springs up when let go.

Accession Number: 2019.ast.173

Alternative Name: Triplett Transistor Analyzer

Primary Materials:

Plastic, Metal: Iron Alloy, Metal: Copper, Metal: Copper Alloy


Printed directly on the bottom of the control panel: “MODEL 3490-A TRANSISTOR ANALYZER”

Printed on a blue sticker affixed to the control panel: “UNIVERSITY OF TORONTO

There are some pen markings consisting of letters inside circles on the panel around plug-type attachments in the panel to the left of the rightmost indicator dial.

Dimensions (cm):


This Transistor Analyzer enables the analysis of the relationship between the current a transistor permits to flow through it when a given current is applied.


Excellent: The case is in very good condition although the corner protectors and latches are slightly corroded across their surfaces. The instrument itself is in excellent condition, with very little sign of use or wear. The plastic bag holding the pair of keys is yellowed and brittle, but intact.

Associated Instruments:


Triplett Electrical Instrument Co., Bluffton, Ohio

Date of Manufacture: c. 1963


This object was likely moved from the David Dunlap Observatory in Richmond Hill in 2008, upon the sale of the observatory. It was stored at the Department of Astronomy and Astrophysics until 2017, when it was moved to a new storage location in McLennan Physical Laboratories.

Additional Information and References:

The 3490-A Triplett Transistor Analyzer handbook can be found <a href=””>here</a>, at Triplett’s website..

Historical Notes: