Design DocumentShiley School of Engineering, University of Portland

EE/CS 480A Senior Design Project Preparation

Magnetic Manipulator

Team 125Marley Rutkowski (Fall Team Lead), John Olennikov,

Chad Perkins, Benjamin YounceFaculty Advisor: Dr. Robert Albright Industrial Advisor: Andy McConnell

Client: Dr. Mark Utlaut

November 15th, 2013

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Table of Contents Page

Introduction....................................................................................................................................2

High-Level Architecture.................................................................................................................4

Construction Specifications...........................................................................................................6

Component Structure.....................................................................................................................7

Software Architecture..................................................................................................................11

System Test Plan.........................................................................................................................12

Development Plan, Milestones, Assumptions, Risks, and Facilities............................................13

Final Budget.................................................................................................................................13

Conclusion...................................................................................................................................13

Bibliography.................................................................................................................................14

Glossary.......................................................................................................................................15

Appendix A..................................................................................................................................16

Figure 1. System Layout................................................................................................................4

Figure 2. System Block Diagram...................................................................................................5

Figure 3. Electromagnet Layout....................................................................................................7

Figure 4. System Schematic..........................................................................................................9

Figure 5. Magnet Field Visualization...........................................................................................10

Figure 6. DC to DC Adjustable Voltage Regulator/ Power Supply DC Boost Converter Schematic....................................................................................................................................11

Figure 7. 7805 DC Voltage Regulator IC Schematic...................................................................12

Figure 8. Software Components..................................................................................................13

Figure 9. User Interface Diagram................................................................................................13

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Introduction

Team 125 has designed a magnetic levitation device that will manipulate a small metal object, controlling its movement in a small area of vertical 1D space without any physical interaction. The team hopes to further expand on this process to achieve controlled levitation in 2D space in which an object can be moved left, right, up and down.

Levitation will be achieved by switching the electromagnets on and off above the levitating object to maintain its desired position. The system will monitor levitation position of the object, and if it is below the desired position, the electromagnet is fully powered. It is powered down again when the object is at the desired position. Stable levitation is achieved by repeating this process very rapidly. The system layout is detailed in Figure 1. The user will be able to adjust the desired vertical position of the levitating object. An Arduino microcontroller will monitor the position of the object by decreasing the percentage of the time that the power to the electromagnet remains on to allow the object to drop, and increasing this time to lift the object. Team 125 hopes to expand the device to achieve horizontal movement by using a second electromagnet positioned adjacent to the original one to pull the object to the side, eventually achieving stable levitation under the second electromagnet.

Many examples exist of systems that have achieved levitation comprised of a single electromagnet, coupled with a Hall Sensor at the tip of the electromagnet, and positioned above a magnetic object. Team 125’s system will expand upon this idea with an added adaptability of position control. Accurate manipulation of the object will require experimentation once the team has the physical system of the Magnetic Manipulator set up. Achieving proper functionality at the high speed at which the system will have to adjust electromagnet strength in order to stabilize the magnet will the primary challenge of the system. It will have to be precise, and it will be difficult to identify what is causing problems in the system. However, by choosing an Arduino as the center of the team’s logical system, there will be opportunities to fine-tune the system to work as desired. In the team’s finished project, the user will be able to control the levitation movement using a computer connected by serial to the microcontroller, as well as manipulate the levitating object in a pre-programmed movement pattern.

This concept could eventually be expanded to utilize additional adjacent electromagnets to achieve levitation in a larger area, and possibly in 3D space. The device will serve as a conceptual demonstration for a technology that can be applied to numerous fields, potentially including manufacturing or even eventually in patient medical surgery.

In this document Team 125 will go over the Magnetic Manipulator design and how it will be implemented. First, high-level architecture will be discussed; each of the system components, their functionality, how they interact and how they fit the requirements of the system. This document will then delve deeper into the component structure of the system, giving details on how components will be designed and implemented. Team 125’s plan will be detailed in the system test plan section. The project development plan, as well as the team’s milestones, assumptions, risks, and required facilities, will also be discussed. Finally, Team 125’s final budget will be provided.

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Figure 1. System Layout

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High-Level Architecture Team 125’s magnetic levitation system will require at least 9 major components: an Arduino microcontroller, computer, electromagnet*, Hall sensor*, levitating object, power source, transistor*, voltage regulator*, and an enable switch. The primary goal of Team 125 will be to achieve controlled levitation under a single electromagnet in one dimension. Once this has been completed, the team hopes to achieve controlled levitation in two dimensions by adding a second electromagnet. The inclusion of a second electromagnet will require an additional set of each of the control system components marked by an ‘ * ’, in order to control the second electromagnet. Figure 2 is a block diagram of all of the system components and how they interact. Further information on their functions and the specific parts being used can be found below.

Figure 2. System Block Diagram 1-Arduino Microcontroller: The Arduino microcontroller is the central brains of Team 125’s system. It is responsible for interpreting commands from and providing information to the user, tracking the levitation of the object through the Hall sensor, and controlling the power given to the electromagnet via the transistor.

User input data will be received by the Arduino as bytes sent over a serial wire by the computer. When commands are available in its buffer, the Arduino will read and interpret them in order to determine how the state of the system should be affected.

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System state data will be encoded by the Arduino and sent over serial to the computer in order to provide the user with information to improve system control.

Hall sensor data will be read in by the Arduino on an analog pin. Its value will be used to track the position of the levitating object at any given time.

The levitating object position will be used by the Arduino in order to determine how to control the electromagnet given the present position of the levitating object, the desired position, and the change since the last measurement.

2-Computer: The computer will serve as the user interface for the magnetic manipulation system. The user will be able to input commands into a custom GUI which will be encoded and sent over serial to the Arduino to be executed. The GUI app may also have to buffer commands to make sure that they are not sent too fast for the Arduino to read because it has a serial queue of limited size. The GUI should also decode and display pertinent data about the system state, received from the Arduino over serial. 3-Electromagnet(s): The electromagnet creates the magnetic field that interacts with the levitating object keeping it in place. It is activated and deactivated by the transistor that controls the power provided to it. The electromagnet must be powerful enough to maintain levitation of our object within a maximum range of at least 2 inches. 4-Hall Sensor(s): Hall sensor data will be used to gather information on the position of the levitating object. A Hall sensor varies its output voltage in response to the magnetic field; the Arduino will monitor this data on one of its analog input pins. From this information the Arduino will be able to extrapolate the position of the levitating object at the given time. The Hall sensors must be strong enough to accurately sense the magnetic flux of a ferromagnetic with an induced charge strong within a 2-inch range.

5-Levitating Object: This is the object that the system is working to levitate. It has a force exerted on it be the field of the electromagnet which counters the force of gravity, and the Hall Sensor reads the value of the magnetic field produced by this object to provide information on its position. The team will design the Magnetic Manipulator to levitate a 1/2 inch diameter by 1/8 inch thick disc grade N48 Iron-Boron Neodymium magnet.

6-Power Source:The power source provides the energy necessary to activate the electromagnets. Team

125 will use a power source that meets the power requirements of the electromagnets. In preliminary lab tests using a physical concepts demonstration magnet team 125 was able to estimate the amount of power needed to lift the magnets of interest at 2 inches. Tests showed that lifting at such a range with the test electromagnet required about 20W of power (2.92V at 6.1A). Therefore based on current research and experimentation the Magnetic Manipulator

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system will require a 12V DC power supply that can supply at least 20W of power. Until further notice, the team will use a supply from the University of Portland Senior design laboratory. 7-Transistor(s): A transistor will be necessary to switch the power to the electromagnet on and off. The transistor will take power, provided by the power source, through the power regulator. The transistor will then supply power to the electromagnet when activated, and supply no power when not activated. A digital control signal from the Arduino will be used to activate and deactivate the transistor. 8-Voltage Regulator(s):

The voltage regulator maintains a constant voltage supply to the system, independent of the power supply and the current load. It takes power in from the power source and provides power to the transistor circuit that is responsible for controlling power supplied to the electromagnet. It may be necessary to use an adjustable power regulator so that the output voltage will be adjusted by the Arduino via an analog signal. The technical specifications of the team’s voltage regulator will depend on the power supply and electromagnets that Team 125 chooses to use in the system. 9-Enable Switch:

Team 125 will include a physical switch that can be used to enable and disable the levitation system. The switch will be connected to one of the Arduino’s digital input ports. When disabled, the electromagnets will have no power supplied to them. When enabled, the system will work as specified.

Construction Specifications System Layout:

Figure 3 depicts how the team plans to lay out the electromagnets and Hall effect sensors if system is extended to execute controlled levitation in two dimensions. For the team’s primary one-dimension goal, one of the electromagnet and Hall sensor systems will be utilized.

Figure 3. Electromagnet Layout

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Stand:Team 125 will build a stand to suspend the electromagnets above the area of

manipulation. This stand must be sturdy, but it must also allow for an unobstructed view of the Magnetic Levitator at work. The team must also be able to place the system electronics somewhere that the magnetic fields generated by the electromagnets will not interfere with them. In order to achieve these goals, the team will use a hangman-style stand that will allow for an unobstructed view at three out of four angles. With this design, the electronics will be placed on the base of the stand of the Magnetic Manipulator, opposite of the levitation area. The primary construction material of the stand will be Plexiglas. Constructing the stand from Plexiglas will allow the system to have an unobstructed view from the back. Figure 1, provided above, demonstrates how the system will look. System Dimensions:

The maximum distance of magnetic manipulation control that the system should achieve is 2 inches, so the electromagnets will have to be mounted high enough to allow for improvement from this goal with some leeway. However, the levitating magnet will not be able to move too close to the electromagnet or else it will be attracted to the ferromagnetic iron core, so our manipulation range will be approximately 0.5-2 inches. By building the mounting structure so that the electromagnets are about a foot above the base of the mount, there will be enough room for improvement on the team’s 2-inch goal.

The electromagnet(s) will have to be far enough away from the vertical part of the stand so that the movement of the levitating object will not be obstructed. The first electromagnet will be placed 2 inches from the vertical part of the stand to allow for enough space. This will put the entire top structure, or overhang, of the stand at approximately 5 inches.

Component Structure This section details the structure of each component of the magnetic manipulator. It displays the parts that have been chosen by Team 125 and how they will be effectively integrated into the system. Figure 4 is a system schematic showing all of the system components and how they are integrated.

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Figure 4. System Schematic

Arduino:Team 125 will use an Arduino Due to control the Magnetic Manipulator system.

Maintaining stable levitation will require very rapid adjustments to the magnetic field supporting the object, and the Due contains the quickest processor of all of the Arduino microprocessor boards. Unlike the other boards it utilizes an Arm processor with a clock speed of 84 MHz, which will allow the system to have a high turnover rate. The Due has 521kB if flash memory available to the user, as well as 96 kB of SRAM which will be plenty of memory since the system will not need to store much information. The board has 54 digital I/O pins, 12 analog input pins and 2 analog output pins, many more than the teams’ system will require.

A key difference of the Arduino Due and the other Arduino products is that it has an operating voltage of 3.3V for all of its pins, whereas other Arduinos run on 5V. This means that all of Team 125’s components that interact directly with the Arduino Due must also operate in a 0-3.3V range. This includes the Hall sensor(s) and transistor(s) that will have to be integrated with the board. The Analog input pins on the Due are 12 bit (i.e. 4096 different values), representing values in the range 0-3.3V, meaning they have an accuracy of approximately 0.806mV. Electromagnet(s):

Team 125 will use a Ginsberg Solenoid/Electromagnet with a steel core. The type of electromagnet chosen is important because it will affect how the levitated magnet will respond to its magnetic field. The solenoid measures 8” x 4” x 4” with a ¾” x 6” removable steel core. It will be powered by a 12V DC input and provide more than enough force to lift and suspend a small neodymium magnet in midair. The electromagnet will be powered by a transistor circuit that activates and deactivates based on the negative feedback of the system. The electromagnet is expected to maintain a minimum distance of 2 inches between itself and the neodymium magnet that it levitates.

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The positive lead of the electromagnet will be connected to the positive out of the voltage regulator, and its negative terminal will be connected to the collector of its controlling transistor. It will also be connected in parallel with a diode to dissipate backflow current with its cathode wired to the positive lead and its anode to the negative lead (and transistor collector).

Hall Sensor(s):The magnetic manipulator will utilize an A1326 linear Hall effect sensor with analog

output. This sensor can be powered by the Arduino at 5V and will have a quiescent voltage output of 2.5V with a sensitivity of 2.5mV/G. However since the output voltage range of this IC is 0-5V a voltage divider to bring the range down to 0-3.3v will be needed, this will decrease the sensitivity to 1.67mV/G. Such a divider circuit will be made with a 1kOhm and 2kOhm resistors in series, the Arduino monitors the voltage between the resistors through an analog input pin. The Arduino Due’s analog input pins have an accuracy of about 0.806mV per integer; therefore, using this sensor, Team 125 will be able to interpret the strength of the magnetic field at an accuracy of approximately 0.48G. If in testing the team finds that this is not accurate enough, the Hall sensor signal can be amplified and a voltage divider can be used to get more accurate data.

Levitating Object: Team 125 will design the Magnetic Manipulator to levitate a 1/2 inch diameter by 1/8 inch thick disc grade N48 Iron-Boron Neodymium magnet. Such a magnet weighs approximately 3g and has a pull force of 6.1lb (placed directly against steel). According experimenting done by K&J Magnetics the magnetic field strength of such a magnet 2 inch away on axis is approximately 6.8 gauss. Figure 5 displays the shape and strength of the magnetic field. Neodymium magnets are the strongest permanent magnets in the world, which makes them perfect for our application where the Magnetic Manipulator will require the greatest ratio of field strength to mass in order to support the object across a large air gap. Team 125 hopes to be able to extend the project to the levitation of other sizes/types of magnets and even ferromagnetic materials (at smaller ranges), once the team has achieved its goal with the Neodymium magnets specified above.

Figure 5. Magnet Field Visualization Transistor(s):

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A TIP 120 NPN transistor will be used in the Magnetic Manipulator. The maximum collector-base voltage of the TIP120 is 60V, the DC collector current is 5A, and collector dissipation (TC=25°C) is 65W. This is way above the system specifications where the Magnetic Manipulator is expected to run on around 12V with less than 1A, meaning that the power of its system would be around 12-24 watts. The maximum collector cut-off current of the transistor is 0.5mA, and the base-emitter on voltage is 2.5V which can be easily supplied by the Arduino Due outputs which can provide 3-15mA, and have a maximum voltage of 3.3V.

The transistor will be wired with its base connected to the Arduino through a 1KOhm resistor. The emitter will be wired to ground, and the collector will be wired to both the negative lead to the electromagnet and the anode of a diode. The diode will be wired in parallel with the electromagnet in order to prevent any backflow current created when the electromagnet turns off from propagating back into the system. Therefore, its cathode will be connected to the positive lead of the electromagnet. Voltage Regulator(s):

Team 125 will use a high power DC-to-DC adjustable voltage regulator/power supply DC boost converter. The regulator is present in the system to stabilize the voltage from the source and raise the voltage and/or power of the power source. The voltage regulator has a range of 4.5-32V at the input and is capable of 5-42V at the output. The current limit through the regulator is 6A. The power output capability of the boost converter is much higher than the Magnetic Manipulator will need, but the power boost converter in the regulator will give the operator the ability to raise or lower the voltage supplied by the source without changing the current supplied to the electromagnet.

The voltage regulator will be wired between the power switch and the electromagnet. The second pole of the power switch will be wired to the positive input of the voltage regulator. The positive output of the voltage regulator will be connected to the positive lead of the electromagnet.

The voltage regulator/boost converter that the team will use is a purchased product that is a complete circuit on its own. A schematic of the device is shown in Figure 6 below.

Figure 6. DC to DC Adjustable Voltage Regulator/ Power Supply DC Boost Converter Schematic

Figure 7 displays the schematic of the 7805 voltage regulator IC that is an element of the voltage regulator/boost circuit.

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Figure 7. 7805 DC Voltage Regulator IC Schematic

Enable Switch: Team 125 will use a toggle switch with ratings of up to 5A and 28V DC, manufactured by TE Connectivity. This is much more power than the Arduino will ever require, so the switch should integrate effectively into our system. The system enable switch will be wired with a positive lead to 3.3V and a negative lead to a digital “in” on the Arduino. The team will also wire a switch in series with the power source and power regulator so that an operator can quickly shut off power in case of emergency.

Software ArchitectureThe user can affect the circuit only by interacting with the provided interface. The user,

through the interface, can enter an input that decides how the object should be raised or lowered. The interface then communicates with the Arduino chip and interprets the user data. The Arduino, in response, sends back present statistics that will be displayed to the user via the interface. The Arduino monitors the input values of the Hall sensors in the circuit and manipulates the pulse frequency to manipulate the object. The Arduino chip also runs calculations to determine the strength of the magnetic field and calculate the levitating object’s distance from the magnets.

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Figure 8. Software Components

User InterfaceThe user interface will be designed using the Processing programming language. As

shown in Figure 9, the interface will consist of a data and a user input container. Section 1 contains and displays all the relevant data related to the program. The user-set “Pulse Frequency” is shown in a text view as shown in Section 2. Section 3 and Section 4 are also text views that display the calculated values for the “Magnetic Field” strength and the distance that the object is from the magnets. Section 5 contains components which allow the user to interact with the device. If the users decide to raise or lower the object, they would press either the “UP” button, as shown in Section 6, or the “DOWN” button, as shown in Section 7.

Figure 9. User Interface Diagram

System Test PlanTEST 1. Steadily levitate one Neodymium magnet.

1. Turn on the power source.2. Carefully place the magnet about 1 inch directly below the electromagnet in mid air.

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Note: For a passing result the magnet should levitate steadily underneath the electromagnet.

TEST 2. Use the GUI to steadily move the Neodymium magnet vertically, up and down.1. With the magnet statically levitating from TEST 1.2. Use the up button on the GUI to move the magnet upward 0.5 inch.

Note: For a passing result the magnet should move steadily upward toward the electromagnet 0.5 inches and settle, levitating steadily 0.5 inch higher than it was previously.

3. Use the down button on the GUI to move the magnet downward 1 inch.Note: For a passing result the magnet should move steadily downward away from the electromagnet 1 inch and settle, levitating steadily 1 inch lower than it was previously.

Development Plan, Milestones, Assumptions, Risks, and FacilitiesRefer to the Requirements and Functional Specifications v1.0 document for a complete list of Team 125’s current milestones, assumptions, risks and facilities required.

Final BudgetSee Appendix A - Final Budget (p16)

ConclusionTeam 125 will strive to develop a system that will achieve stable magnetic manipulation

controllable in at least the vertical plane. The team has chosen a flexible design, so after achieving this result Team 125 hopes to have the opportunity to extend our goals into further dimensions. The Magnetic Manipulator’s design will allow the user to have a high level of control, but still have insight on how it is working. In developing Team 125’s system, the team will face lots of trial and error testing in order to develop the code to make the device work properly. Therefore, one of the team’s biggest challenges will be the testing of the Magnetic Manipulator, and the potential of accidentally damaging system components. Team 125 will order extra parts so that if components are damaged, progress is not greatly inhibited. Although the team’s ultimate goal of 2D magnetic manipulation is a stretch on the skills of each team member, Team 125 has provided itself with goals of increasing difficulty and achievable milestones that will lead to the ultimate success of the Magnetic Manipulator.

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BibliographyArduino. 2013. http://arduino.cc/en/Guide/ArduinoDue (accessed September 5, 2013).

DigiKey. http://www.digikey.com/ (accessed September 7, 2013).

HacknMod. 2013. http://hacknmod.com/hack/how-to-controlled-levitation-using-magnets-microcontrollers/ (accessed September 15, 2013).

Instructables. 2013. http://www.instructables.com/id/Use-Arduino-with-TIP120-transistor-to-control-moto/(accessed September 11, 2013).

Instructables. 2013.http://www.instructables.com/id/Controlling-solenoids-with-arduino/?ALLSTEPS(accessed October 27, 2013).

Mekinikuv Blog. 2009.http://mekonik.wordpress.com/2009/03/17/arduino-magnet-levitation/ (accessed October 30, 2013).

SparkFun. https://www.sparkfun.com/products/9312 (accessed September 4, 2013).

YouTube. http://www.youtube.com (accessed September 1, 2013).

Zelcom. 2013.http://zeltom.com/products/magneticlevitation (accessed October 27, 2013).

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GlossaryArduino: A single-board microcontroller to make using electronics in multidisciplinary projects more accessible.

Electromagnet: A type of magnet in which the magnetic field is produced by electric current flowing through coils.

Enable Switch: Can be switched on or off to provide high/low logic.

Hall Sensor: A transducer that varies its output voltage in response to a magnetic field.

Team 125: A Senior Design Project team consisting of Marley, John, Chad, and Ben.

Magnetic Field: A region around a magnetic material or a moving electric charge within which the force of magnetism acts.

Magnetic Levitation: A method by which an object is suspended with no support other than magnetic fields.

Magnetic Manipulator: A device constructed by Team 125 that sustains controlled levitation of a small object.

Neodymium Magnets: A member of the rare earth magnet family. They are called "rare earth" because Neodymium is a member of the "rare earth" elements on the periodic table. Neodymium magnets are the strongest of the rare earth magnets and are the strongest permanent magnets in the world.

Power Source: A device that supplies electric power to an electrical load.

Pull Force: The holding force of a magnet when it placed up against a steel plate. This value is determined in a lab with a pull force tester.

Transistor: A semiconductor device used to amplify and switch electronic signals and electrical power.

Solenoid: A coil wound into a tightly packed helix used to create magnetic fields.

Transistor: A semiconductor device with three connections, capable of amplification in addition to rectification.

Voltage Regulator: A device that automatically maintains a constant voltage level.

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Appendix AFinal Budget

Item Qty Unit Price

Cost Supplier Webpage

Arduino Due 2 $46.95 $93.90 Virtuabotix https://www.virtuabotix.com/productpage/7640152111228/

Hall Sensor A1326LLHLT-T

5 $2.20 $11.00 Digikey http://www.digikey.com/product-detail/en/A1326LLHLT-T/620-1403-1-ND/2639995

TIP120 Transistor

5 $0.66 $3.30 Digikey http://www.digikey.com/product-detail/en/TIP120/TIP120-ND/1052441

Bread Board 1 $7.95 $7.95 Virtuabotix https://www.virtuabotix.com/productpage/608641373295/

Toggle Switch 2 $3.17 $6.34 Digikey http://www.digikey.com/product-detail/en/A101SYZQ04/450-1523-ND/1021810

Power

Regulator

#090480

2 11.20 22.40 AliExpress http://www.aliexpress.com/item/DC-Adjustable-Voltage-Regulator-DC-4-5-32V-to-5-42V-High-Power-Industrial-Power-Supply/678569187.html

Radial Magnet 5 $1.28 $6.40 Digikey http://www.digikey.com/product-detail/en/1%2F2%22DIA%20X%201%2F8%22THICK/469-1002-ND/555326

10 N48 Magnets

2 $7.96 $14.92 Amazon http://www.amazon.com/Neodymium-Magnets-inch-Disc-N48/dp/B001KV38ES

Solenoid 2 $26.98 $53.96 Teacher Supply

http://www.teachersupplysource.co

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m/product/63947/american-educational-products/ginsberg-science-and-labware/electricity/ginsberg-solenoid-electromagnet-with-core/

Diode 1N5817 5 $0.44 $2.20 Digikey http://www.digikey.com/product-detail/en/1N5817-T/1N5817DICT-ND/190530

*Stand Expenses

1 $40 $40 Tap Plastics http://www.tapplastics.com

Shipping CostDigikey $7.49-$9.75 (depending on weight)Virtuabotix FREEAliExpress FREEAmazon $7.99Teacher Supply $15.87

Total cost of parts: $262.37Total cost of shipping: $33.61Total cost of project: $295.98