Accession Number:

Instrument Name: Ammeter


Object has a black plastic case with a black painted metal cover. There are two silver knobs on the top of the object approximately 2.5 cm away from one another. There is a black leather carrying strap on the right hand side attached to the bottom and the top of the galvanometer with screws. An adjustable black plastic knob that has options of “HIGH” and “LOW” is located on the right hand side of the object below the leather handle. There are four rubber feet on the left hand side of the object.The meter has a mirrored scale and knife-edge pointer behind a plastic screen. The object is listed as “Model 433 No. 140705″. The manufacturer’s label contains the following information: “DAYSTROM INCORPORATED; WESTON INSTRUMENTS DIVISION; NEWARK, N.J. ZERO; U.S.A. CORRECTOR.” The back of the object has four rubber feet on its back. Weighs approximately 2 – 2.5 lbs.

Alternative Name: Daystrom Portable Ammeter

Primary Materials: Other metal, leather, rubber, plastic


Below the manufacturer label on the front of the object is a hand-etched inscription “2515 D”. On the bottom of the object is a white circular stamp with “W 59″ in the middle. There is a number 6 stamped in white less than a 1 cm away from this circular stamp, also on the bottom of the object. On the back of the object between two of its rubber feet is a series of numbers “2903005″ also stamped in white.

Dimensions (cm):

Length = 9 cm , Width = 12.5 cm, Height = 16 cm


Ammeters measure the electric current in a circuit, the unit for which is amperes (A). This ammeter covers a standard frequency between 25-500 cycles. This instrument is also meant to be hand-calibrated.


Good condition: there is very little wear and tear other than an occasional scratch on the surface of the bakelite plastic. The two knobs on the top of the ammeter have a dull finish that may be a thin layer of corrosion. The leather strap is fraying slightly along its edges and is stiffening with age. The dust that coated the object was brushed off with a soft bristle brush during examination.

Associated Instruments: N/A

Manufacturer: Weston Instruments Division

Date of Manufacture: c.1960


The manufacturer’s label gives Newark, N.J. (New Jersey), U.S.A. as this object’s place of manufacture

Additional Information and References:

Donated to UTSIC: Yes

Historical Notes:

Model 433 ammeters have a rated accuracy of 0.75% when used in the horizontal position, according to historic catalogues.