User:GEEN2400/sandbox

=Electric Fence Communication Unit= A team of five undergraduate engineers from the University of Colorado Boulder have been commissioned by Jacobs Springs Farm's to build an electric fence charger for the group's projects class: Engineering Projects for the Community. The group has one semester to design, prototype, and build their project before presenting it at the design expo on Saturday, December 5th, 2015. The design is intended to be completely open source.

The Team
Joel Knepper Junior, Mechanical Engineering

Slator Aplin Junior, Mechanical Engineering

Zoe Welz Sophomore, Environmental Engineering

Andy Granger Sophomore, Environmental Engineering

Haley Basti Freshman, Open Option Engineer

New Age of Farming
Houssney's long term goal for the team and for the fence charger is to be able to provide farmers today with a way to do managed intensive rotational grazing with a relatively low cost electric fence charger that has communication abilities. One of Houssney's issues with chargers available today is that they cannot communicate to the user when the fence is not working properly. He wants to be able to set a "threshold" of when the fence will deliver a shock and when it notifies him that the fence is being touched too frequently, because the fence will almost always be touching plant tissue or other material that will complete the circuit of the fence on deliver an unnecessary shock.

Problem Statement
The client, André Houssney, is looking for an unconventional design for a fence charger for his farm. His goal is to obtain a product that can communicate to him via WiFi if/when there is no current running through the fence, that is "portable" (can be moved to different parts of the farm while still connected to a 120 Volt electric wall outlet, can be used for multiple types of livestock), and is open source and could be recreated by the overage farmer with ease.

Many of the fence chargers available today are extremely expensive and can break easily. Houssney has experienced problems with chargers in the past that have failed due to water damage, so another priority for the group will be finding a way to waterproof the system.

The Prototype
The prototype was built using the open source Particle Photon board, which uses a Broadcom WiFi chip, and a powerful STM32 ARM Cortex-M3 microcontroller. The full data sheet for the Photon is available on Particle 's website. The Photon was hooked up to a breadboard and powered by a 9 Volt battery, whose voltage what regulated down to 5 volts to power the board and the current sensor. The sensor sends a reading back to the Photon which communicates to the client's smartphone via Particle's app. The prototype confirmed the design concept met Houssney's requirements of a charger that could communicate to the user.

User Testing
Results of user testing showed that the value obtained from the current sensor were lower than expected.

Research and Development

 * quote='Early alternating current (AC) fence chargers used a transformer and a mechanically driven switch to generate the electrical pulses. The pulses were wide and the voltage unpredictable, with no-load peaks in excess of 10,000 volts and a rapid drop in voltage as the fence leakage increased. The switch mechanism was prone to failure. Later systems replaced the switch with a solid-state circuit, with an improvement in longevity but no change in pulse width or voltage control.

"Weed burner" fence chargers were popular for a time and featured a longer-duration output pulse that would destroy weeds touching the fence. These were responsible for many grass fires when used during dry weather. Although still available, they have declined in popularity.

Most modern fences emit pulses of high voltage at a given interval of time, and don't take into account whether is there an animal or person touching the conductive wires, except for the voltage multiplier based electric fence charger that stores high voltage potential and dumps its charges as soon as a conductive load (grounded animal/person) touches the wires.

Depending on the area to be fenced and remoteness of its location, fence energizers may be hooked into a permanent electrical circuit, they may be run by lead-acid or dry cell batteries, or a smaller battery kept charged by a solar panel. The power consumption of a fence in good condition is low, and so a lead-acid battery powering several hundred metres of fence may last for several weeks on a single charge. For shorter periods dry cell batteries may be used. Some energizers can be powered by more than one source.

Materials

 * Resistors
 * 2 - 51k Ohms 5%
 * 1 - 470 Ohms 5%
 * 1 - 5.1k Ohms 5%
 * 1 - 10 Ohms 5%
 * 1 - 10k Ohms 5%
 * Integrated Circuits
 * 1 - 555 Timer (LM555CM)
 * 1 - Operational Amplifier (UA741CP)
 * Capacitors
 * 1 - Aluminum Electrolytic Capacitor - Leaded 10μF 50V
 * 1 - Ceramic Capacitor - .01μF
 * 1 - Ceramic Capacitor - 470pF
 * Transistors
 * 3 - Bipolar Transistors (TIP31C)
 * Transformer
 * 3500v Neon Sign Transformer
 * Terminal Strip
 * Barrier Terminal Block
 * Solder-able Breadboard
 * 63 line Solder-able Breadboard
 * Microcontroller
 * Particle Photon with Headers