Macro Sensor LVDTs Ensure Proper Currency Dispensing in ATM Machines

Pennsauken, NJ, May 12, 2009... Macro Sensors PR 750 Series of 3/4 inch (19 mm) diameter AC-operated LVDTs are serving as measurement feedback devices in the paper bill detector of automated teller machines (ATMs) to ensure proper currency dispensing.

In an ATM, Macro Sensors' PR 750 Series of Linear Position Sensors are used to measure the separation of a pair of rollers, whereby bills passing between the rollers displace the LVDT core. As the bills pass between the rollers, the LVDT output changes according to their thickness. As a typical bill measures 0.0003" (0.0075mm) thick, the LVDT will detect any derivation should two or more bills get stuck together.

As the ATM can be used hundreds of times during the course of a day, the repeatability and reliability of the linear position sensor are of key importance. Since there is no contact between the LVDT core and coil of the PR Series, there is no friction to cause inaccuracy or part of the LVDT to wear out during the service life of the ATM. To account for any dirt accumulation on the rollers, a sample readout is made for one complete revolution. Any zero-offset value is stored and, then, compared against the LVDT output as the customer's currency is measured. This eliminates the risk of passing an unexpected number of bills, while at the same time compensates for any variation of the roller surfaces.

For more information on Macro Sensors PR Series of Linear Position Sensors, refer to the web site at or contact the factory at

About Macro Sensors

Macro Sensors' extensive line of linear and rotary sensors are used for position measurement and feedback in a variety of industrial applications including factory automation, motion control systems, metal fabricating, automotive assembly as well as power plants, gas/steam turbines. Incorporated in 1994, the Company offers more than 200 years of cumulative design and manufacturing experience by its key staff in serving its OEM and end-user international customer base. On June 1, 2005, Macro Sensors was acquired by AST, manufacturer of state-of-the-art (Micro Electro Mechanical Structures) MEMS-based pressure sensors, transducers, and transmitters. Common applications of AST sensor products are in industrial OEM, hydraulic systems, fuel cells, medical gases, HVAC/R, refrigeration, oil & gas exploration/production, and off-road vehicles. For more information on AST products and technology, visit the AST website at

U.S. Route 130 North,
Bldg. 22, Pennsauken,
NJ 08110-1541
Tel: 856-662-8000
Fax: 856-317-1005

Media Contact:
Jean Carl

Engineering Contact:
Joseph Vu

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