Money Sorting Machines (Part 3)

Bill Validation

In this final article of his money sorting machine series, Jeff wraps up his coin sorting project and examines how a bill validator can tell one bill’s denomination from another.

By Jeff Bachiochi

Most of us connect Ben Franklin with kites and lightning. He was also a printer and might be best known for Poor Richard’s Almanack—a yearly publication that he published from 1732 to 1758 under the pseudonym of Richard Saunders. It was a best-seller and thanks to his wit and wisdom, his portrait was added to the cover of The Old Farmer’s Almanac in 1851—appearing opposite the founder Robert B. Thomas. It remains there today.

As a master printer and engraver, in 1730 Franklin began printing all paper money issued by Pennsylvania, New Jersey and Delaware. Paper money was first introduced in the region in 1723, but it remained a hot political issue. That’s because it helped farmers and tradesmen, while merchants and landowners wanted it eliminated or limited in its circulation. Paper money printed from ordinary type was easy to counterfeit, but Ben’s ingenuity solved that problem by printing pictures of leaves on every piece of money. Counterfeiters could not duplicate—or even imitate—the fine lines and irregular patterns. The process by which he made the printing plates was secret, but were probably cast in type metal from molds made by pressing leaves into plaster of Paris. There began the Feds vigilant effort to thwart counterfeiters.

Today every aspect of our paper currency is controlled—from its design to its printing, as well as its monitoring and destruction. The paper (which is not paper) and ink (multiple types and formulas) are fabricated for the express use by the Department of Engraving. That department is the Treasury bureau responsible for paper money—as opposed to the U.S Mint, which is the Treasury bureau responsible for coinage. US currency consists of 25% linen and 75% cotton and contains small randomly disbursed red and blue security fibers embedded throughout the material. Depending on the denomination the material is further enhanced by embedding security threads, ribbons and watermarks. Since 1996, printing with colored and color changing inks make the new currency pop. While older black and green currency is rather drab in comparison, it is still legal tender and remains the target of most counterfeiters.

The previous two parts of this article series (December 329 and January 330) centered around coinage. Before we look at bill validation for paper money, I need to finish up with that project. I had purchased a few Coin Acceptors and showed how they are used to identify coinage, especially but not limited to US coins. The acceptance and dispensing of money is presently used in many ways today, including vending machines and ATMs. The discussion also included National Automatic Merchandising Association (NAMA), the organization that developed the international specification for the Multi-Drop Bus/ Internal Communication Protocol (MDB/CP) released in July 2010. The MDB/ICP enables communication between a master controller and any of the peripheral hardware like Coin Acceptors and bill validators. By adhering to these guidelines, any manufacturer’s equipment is interchangeable.

Turns out the Coin Acceptors I purchased don’t have the MDB interface necessary to communicate with a Vending Machine Controller (VMC). I reviewed the protocol and VMC/Peripheral Communication Specifications required by the Coin Acceptor/Changer peripheral and began work on developing an MDB interface that would bridge my Coin Acceptor with the multi-drop bus. 

Read the full article in the February 331 issue of Circuit Cellar

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Boost Arduino Mega Capability with 512-KB SRAM & True Parallel Bus Expansion

The Arduino MEGA-2560 is a versatile microcontroller board, but it has only 8 KB SRAM. SCIDYNE recently developed the XMEM+ to enhance a standard MEGA in two ways. It increases SRAM up to 512 KB and provides True Parallel Bus Expansion. The XMEM+ plugs on top using the standard Arduino R3 stack-through connector pattern. This enables you to build systems around multiple Arduino shields. Once enabled in software, the XMEM+ becomes an integral part of the accessible MEGA memory.Scidyne

The XMEM+ also provides a fixed 23K Expansion Bus for connecting custom parallel type circuitry. Buffered Read, Write, Enable, Reset, 8-bit Data, and 16-bit Address signals are fully accessible for off-board prototyping. The XMEM+ makes any Arduino MEGA system much better suited for memory-intensive applications involving extended data logging, deep memory buffers, large arrays, and complex data structures. Target applications include industrial control systems, signage, robotics, IoT, product development, and education.

The introductory price is $39.99.

Source: SCIDYNE Corp.

EMC Measurement Technology

LangerSX near-field probes enable electromagnetic compatibility (EMC) analyses of interferences emitted by electronic boards, components, and IC pins with high internal frequencies. The SX-R3-1 magnetic H-field probe is designed to detect high-frequency magnetic fields with a high geometrical resolution. The field orientation and distribution can be detected by moving the probe around conductor runs, bypass capacitors, EMC components, and within IC pin and supply system areas. The SX-E03 E-field probe detects bus structures and larger components.

The probes have a 1-to-10-GHz frequency range. Their high resolution (the SX R3-1 achieves 1 mm and the SX E03 covers up to 4 mm × 4 mm) enables them to pinpoint RF sources on densely packed boards or on IC pins. The magnetic-field probe heads are electrically shielded. The probes are connected to a spectrum analyzer input via a shielded cable and SMA connectors during measurement. High clock rates of 2 GHz, for example, may result in fifth-order harmonics of up to 10 GHz. These harmonics are coupled out by RF sources on the board (e.g., conductor-run segments, ICs, and other components). They may stimulate other structural parts of the board to oscillate and emit interferences.

Contact Langer for pricing.

Langer EMV-Technik

High-Speed Laser Range Finder Board with IMU


The NavRanger-OEM

The NavRanger-OEM combines a 20,000 samples per second laser range finder with a nine-axis inertial measurement unit (IMU) on a single 3“ × 6“ (7.7 × 15.3 cm) circuit board. The board features I/O resources and processing capability for application-specific control solutions.

The NavRanger‘s laser range finder measures the time of flight of a short light pulse from an IR laser. The time to digital converter has a 65-ps resolution (i.e., approximately 1 cm). The Class 1M laser has a 10-ns pulse width, a 0.8 mW average power, and a 9° × 25° divergence without optics. The detector comprises an avalanche photo diode with a two-point variable-gain amplifier and variable threshold digitizer. These features enable a 10-cm × 10-cm piece of white paper to be detected at 30 m with a laser collimator and 25-mm receiver optics.

The range finder includes I/O to build a robot or scan a solution. The wide range 9-to-28-V input supply voltage enables operation in 12- and 24-V battery environments. The NavRanger‘s IMU is an InvenSense nine-axis MPU-9150, which combines an accelerometer, a gyroscope, and a magnetometer on one chip. A 32-bit Freescale ColdFire MCF52255 microcontroller provides the processing the power and additional I/O. USB and CAN buses provide the board’s high-speed interfaces. The board also has connectors and power to mount a Digi International XBee wireless module and a TTL GPS.

The board comes with embedded software and a client application that runs on a Windows PC or Mac OS X. It also includes modifiable source code for the embedded and client applications. The NavRanger-OEM costs $495.

Integrated Knowledge Systems, Inc.