User:K moreno/ENES-100/project 1

My Instructor's user page which points to this.

Week1 Narrative
Task: Figure out why a Simplex wireless card scanner stopped working and to understand more about it.


 * Copper wires wrapped around card scanner to make a magnetic field
 * Insides of scanner was filled with about a centimeter of durable potting material
 * Used various clay carving tools and a razor blade to remove potting
 * Upon removal, the devices contained 10 wires with various colors connected to a motherboard
 * One of the wires was severed, possibly making it the cause for the device to cease functioning

Next Steps
 * Try to get the device working again
 * Measure the range of the magnetic field it produces

Week2 Narrative
Task: Attempt to get the magnetic field from Simplex card scanner to function again.

The Simplex card scanner needs a transmit frequency of 125 kHz in order to scan cards. Replicating that condition to see if it results in a magnetic field.


 * Used a sweep function generator
 * Detached the copper wires from the circuit board
 * Unwrapped some of the copper wire enough to attach hook clips
 * Used the clips and sent 125 kHz all the way to 2 MHz

No magnetic field emerged. Not even when copper wires were directly inserted into the machine. Later used 9V batteries and alligator clips to send current through the wires. Did not work either.

Next Steps:
 * Locate another proximity card reader of a different brand, broken or already functioning
 * See if the same principles apply

Week3 Narrative
Task: Attempt to get copper coil from Simplex card scanner to emit a oscillating magnetic field.

Proximity card readers and commercial wireless charging products use the principles of an oscillating magnetic field instead of a regular one to function properly. Function generator was originally not working with the copper coil because the wire was coated with a resin and needed to be burned off to establish a proper connection.

Steps Taken and Observations:


 * Connected function generator and oscilloscope to copper coil.
 * Applied several different settings
 * Copper coil emits a high pitched whine
 * Set phone with wireless charger adaptor near it to see if it would charge but produced no results
 * Connected set up to volt meter, with it giving a reading of less than a volt

The manual of the wireless charger product states that the charging base outputs 5 volts so the phone can charge. Afterwards the copper coil ceased emitting a high pitched whine. A 9V battery was added to the set up but produced no results.

Task: Attempt to create an oscillating magnetic field using a different set up.

Found an electric door strike and proceeded to take it apart and see if it still worked. Saw that it uses an electromagnet in order to fulfill its purpose. When connected to a 9V battery, discovered that the electromagnet still functions. Decided to use this to create the oscillating magnetic field.

Results: Using the function generator, it made the magnetic field produced by the electromagnet to oscillate.

Next Steps: Attempt to see the electric door strike electromagnet will be able to charge the phone with the wireless charging adaptor.

Week4 Narrative
Task: Create an alternate transmitter coil that will operate with the existing wireless charger receiver.

Proximity card readers use the same properties of oscillating magnetic fields as wireless chargers. This was proved using a Powerbot Wireless Charger hooked up to an oscilloscope:

The current that the wireless charger was producing was oscillating but at the same time decaying. The next step to see if the oscillating magnetic field obtained last week would work with the wireless charger's receiver and make an electronic device charge.

Steps Taken and Observations:


 * Powerbot wireless charger needs at least five volts and a frequency of 125kHz to operate
 * Hooked up previous experiment's coil to 9V battery and function generator at a setting 125kHz
 * Oscillating magnetic field created, however, device is not charging

Task: Figure out why Powerbot did not work with makeshift oscillating magnetic field.


 * Looked up how wireless chargers work from Power by Proxy
 * Discovered wireless chargers use alternating current to function
 * All batteries use direct current
 * DC vs. AC
 * Alternating current could possibly create oscillating magnetic fields within itself because the direction of the current reverses

Although the battery met the voltage requirements and the function generator met the frequency requirements, the direct current of the battery cannot meet another requirement of the Powerbot, which was needing at least 1500mA. A 9V battery does not come close to producing the required amount of mA.

Next Steps: Find or create a power source that can give the makeshift oscillating magnetic field an alternating current.