EGR 450 Controls Project               Nick Moelker
                                                            August 1999
"The Traveling Sprinkler"
Outline:

I. Proposal
II. Project Description
III. Proposed Solution
IV. Main Components
        i. Timer
        ii. Switch
        iii. Photo eye
        iv. Solenoid Valve
V. Tools ect.
VI. System Guide
VII. Lessons Learned / Challenges
VIII. Conclusion
 

I. Proposal
The proposed Controls Project was to control a traveling sprinkler by using a switch to shut off the water to a solenoid valve in order to make the sprinkler stop. The reason that this is necessary is because without the proper supervision the sprinkler would sprinkle the house when it comes close enough. Another problem is that when it reaches the end of the hose it ruins the lawn by spinning its wheels.

II. Project Description
The traveling sprinkler, pictured in Figure 1, is propelled by water. The water travels through the housing and causes the helicopter sprinkling mechanism to turn. This turning causes the wheels located in the back of the tractor to turn, thus moving the sprinkler forward as long as the water is supplied. By turning off the water supply the tractor will stop, therefore stopping the advance towards the house.

Figure 1. A picture of the traveling sprinkler.

III. Proposed Solution
The main thing that the project is trying to achieve is to stop the sprinkler at a designated place. In order to do this the water supply must be turned off so that the propulsion force is no longer present. The solution to this problem is a simple solenoid valve that can be bought at you local hardware store. The object of this project is to figure out how to activate and deactivate the solenoid valve. This will be done with a photo eye that is set up in the lawn at the appropriate place to detect the presence of the tractor. This photo eye will deactivate the solenoid so that the sprinkler only covers the area that you want. Just for precautions a stop switch and a timer will also be able to deactivate the solenoid valve. See Figure 2 for a state diagram for more information.

IV. Main Components
The project consist of  four main parts. The timer, the switch that will activate the solenoid, the solenoid valve, and the photo eye.

i. The timer will be made up of a 555 timer and several counters. The 555 chip is a pulse generating chip, the counters will each count up to a certain number of pulses, then send a pulse of its own. After a certain number of pulses the last counter will send a pulse to the switch, this pulse will flip the switch and turn off the solenoid. For this project a CA555CE timer was used as the pulse generator and four 74LS161AN counter chips were used.
a. 555 Pulse Generator
b. Counter
ii. The switch that will be used is a flip-flop. A flip-flop is a chip that acts like a latch, it will latch on when 5V is seen at the "set" pin and will turn the latch off if a 5V input is seen at the "clear" pin. The flip-flop that was used in this project is a SN74LS74AN chip.
a. Flip-Flop
iii. The Photo eye that is used in this project is numbered 42RP-604 and is made by Electronics Corporation of America.
a. Photo eye
iv. The solenoid valve that is being used is a 1" valve made for underground watering systems, made by Lawn Genie. The valve was purchased at a local hardware store and is activated by 24V AC.
a. Solenoid Valve
V. Final Project
i. Wiring Schematic
ii. Pictures
V. Tools, Components, ect.
1. Oscilloscope (Tecktronix 2246A)
2. Digital Multimeter with continuity checker (Fluke 8010A and Fluke 76)
3. Circuit Trainer (E & L Instruments)
4. Soldering Iron with thin solder
5. Power Supplies (Picture of PS)
        5 V DC for chips
        24 V AC for solenoid
        12 V DC for Photo eye
6. Several PVC fittings, hose fittings, and a short piece of hose
7. All of the items that are needed for wiring (resistors, caps, leads, chip sockets, terminal strips, ect.)
8. Circuit boards (purchased from Radio Shack)
9. Several Push button Switches
10. A relay that is activated by 5 VDC and can handle 24 VAC
11. Several chips (see information above)
12. Photo eye
13. Solenoid Valve
14. Traveling sprinkler
VI. A Guide on how to run the System

VII. Lessons Learned / Challenges

1. Carefully wire the chips and always draw good schematics that can be used again to wire everything.
2. When moving the circuit from the Circuit Trainer to the circuit boards make sure that you are careful to make good solder connections. i.e.. one bad connection can cause your whole board to malfunction.
3. ALWAYS check for continuity.
4. The data sheets on the 7400 series chips are a big help.
VIII. Conclusion
This project was an incredible learning experience for me. I feel that I have become a better engineer because I was challenged by something that I have never worked with. Since I have a Mechanical emphasis, I learned a lot about what goes into the design of a circuit and the fine detail that goes into getting a simple 7400 series chip to work. To me electricity and circuits was always something that I wanted to stay away from, but after this project I am intrigued by what can be done with some simple chips from Radio Shack. Not only have I learned a lot about circuit design I also learned a lot about documentation and time management, two of the biggest things that can not be taught, but are skills that are developed. I am very happy that I worked on this project and even though it was a lot of work it was worth the effort to see it work.

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