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Wheatstone Bridge

Technical Information

Catalogue No: C0241
Category: General Purpose
Object Type: Test Equipment
Object Name: Wheatstone Bridge
Part No: ?
Serial No: ?
Manufacturer: Croydon Precision Instrument
Division: Unknown
Year of Manufacture: circa 1950
Dimensions: Width (mm): 318
Height (mm): 200
Depth (mm): 215
Weight (g): 645
Location: Rack RAA07 [Main Store]

Portable Wheatstone Bridge


This high quality instrument has a nice solid wooden case and robust controls and was manufactured by the Croydon Precision Instrument company, known as Cropico, in the 1950’s.
The PW1 is a manually balanced Wheatstone bridge with a usable range from 10 milliohms to 11 megohms. Four decades of switched resistances provide four-digit resolution (from 1 milliohm on the 10 ohm range to 1kohm on the 10 megohm range. Separate multiply by and divide by switches, each spanning four decades from 10 to 10,000 act to modify the scaling of the switched resistances.
There is no internal power supply: a battery of at least 2V would have been connected to the Battery terminals.

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of a wheatstone bridge is its ability to provide extremely accurate measurements (in contrast with something like a simple voltage divider). It was invented by Samuel Hunter Christie in 1833 and improved and popularized by Sir Charles Wheatstone in 1843.

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