Weston D.C. Voltmeter, Model 45

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Weston D.C. Voltmeter, Model 45


Electrical Measurement


Front face with lid opened:

Knobs: Toward the top of the box on the front face, there are 3 screw knobs (two on the left, one on the right). Each dial has a knurled surface, and when unscrewed, reveals a metal electrical lead. Above the knobs on the left are circular labels with white text that say “300” and “150”. On the right, a similarly formatted inscription above the right knob has a “+”.

Front face surface: the entire surface is a black, knurly surface. On it is a circular boss that drops below the hinge mounts, such that the user can only see half of the circle. In the boss, there is a quarter-circular slot with glass in it such that the user can see the white label underneath it. A singular needle points to labels marked from 0 to 300, with increments of 20. Below those markings, there are similar markings in red instead of black, that increment by 10 and go from 0 to 150. Below that is the label “WESTON D.C. VOLTMETER”. The individual line increments on the white portion have 10 increments in between each labeled increment, with a longer split marking 5 increments.

Functional Description: This object is intended to measure voltage through use of the leads underneath the screw knobs. One attaches their charged leads to either the 300 or 150 lead and the “+” lead. When this is done, the needle points to the amount of voltage between the user’s charged leads.

The holes on the inside of the lid are probably for storing the electrical lead screw knobs, such that they do not get lost.

The instrument can be used on its back or on its bottom, and the user can use the latch to close the device during storage. When the leather strap was still there, it could be used to carry the device around.

The “correction” knob on the front can be used for fine-tuning/calibrating the instrument’s measurements.

The measurement of voltage can suit many applications, but in this case, it looks like it was for a specific class (The “EE” course prefix probably signifies the electrical engineering department).


Cooper Sheldon, John Wyrzykowski, Ben Weigand, Nick Silvestri


March 1930



Physical Dimensions

Oak case with a leather handle: Length 7.75 x Width 7.75 x Height 4.5"


Glass, Metal, Paper, and Wood


Weston Electrical Instrument Co.


F-552-1M-2-29|WESTON D.C. VOLTMETER, MODEL 45, No [handwritten: “38129”] |
This instrument indicates International Volts and is correct within ½ of 1%|
of full scale value at any part of the scale at [handwritten: “75° F.”] |
For ordinary measurements no temperature correction is required. If greater|
accuracy is desired, multiply readings by:-|
[handwritten: “1-0.00007(t-75° F)”] for the [handwritten: “150&300”] Volt Ranges|
”_________________” “________________” “|
”_________________” “________________” “|
Resistance of [handwritten: “150”] Volt Range [handwritten: “15000”] Int. ohms at [handwritten: “75° F”]|
“ [handwritten: “300”] “ “[handwritten: “30000”] “ “ “ ___________|
“ _________________” “________________” “ “ “ ___________|
Standardized at Weston Laboratory, Newark, N.J., U. S. A.|

Dated [handwritten(cursive): “March 24”] 1930|
Certified [handwritten(cursive): “J.B. Dourden”]


Mechanical Engineering-Engineering Mechanics Building Third Floor Display Case


"Weston D.C. Voltmeter, Model 45", Robert A. Paselk Scientific Instrument Museum. (2010). Accessed on 11/17/2019. https://www2.humboldt.edu/scimus/HSTC.27-35/Descriptions/DCVMeter.htm

Science History Institute. Weston Ammeter Model 45. 2016. Photograph. Science History Institute. Philadelphia. https://digital.sciencehistory.org/works/ht24wj48w.

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Cooper Sheldon, John Wyrzykowski, Ben Weigand, Nick Silvestri, “Weston D.C. Voltmeter, Model 45,” Michigan Tech Inventory of Historic Scientific Instruments, accessed April 17, 2021, https://ihsi.omeka.net/items/show/183.