Kevin Week 12 Blog

Blog Week 12 Requirement:

Explain your setup.

    My Circuit consists of two main parts separated by a control relay.

     The First half of circuit provides voltage to the relay's coil, consists of: 

     4 solar panels, 

     1 Op-Amp IC chip

     2 Resistors (68 and 350 Ohms)

     1 Toggle Switch

     A 12 Volt Power Supply   

     

     The 4 Solar panels are connected in series and provide an input voltage to the Op-Amp.  The Op-Amp is setup in non-inverting  configuration and connected to a 12 VDC power supply through a simple on/off toggle switch along with two resistors.  This configuration provides an approximate voltage 6x the input from the solar panels to the coil of the relay.

    When the Relay is actuated it provides voltage from a second separate 12 VDC power supply to a single pole double throw switch.  This switch has one input and two outputs, with the input being spring loaded to it's "normally closed" contact when no pressure is applied.

    The switch's normally closed contact is connected to a 12VDC pump which is capable of circulating 200 Liters of water per hour.  While the "Normally Open" contacts ar connected to a 12VDC 35W Halogen Flood Light.

     

    The switch itself rests between two spring loaded plates, when enough pressure is applied to the upper plate to overcome the spring's tension the switch actuates and breaks the "normally closed" contact while simultaneously connecting the input to the "normally open" contact.

    The Circuit is actuated by providing light to the solar panels which send a 1.5-2 VDC to the Op-Amp.  It the the toggle switch in in the ON position the Op_amp then actuates the control relay sending power to our pressure switch.  That power then activates the water pump pumping water from a reservoir into a container resting on top of the pressure plate.  As the container fills the increased weight on the pressure plate overcomes the plates' spring tension and compresses the pressure switch into the normally opened position.  This cuts off the voltage the pump, stopping the flow of water, and redirects it to the floodlight.  Light from the Floodlight is then used as a trigger for Chris's circuit (See Chris's Blog Entry for a full breakdown of his circuit.)  

Provide the computer drawing for your individual Rube Goldberg setup.

My Week 12 Circuit Schematic made at www.CircuitLab.com

     Provide photos of the circuit and setup.

 

Solar Panel / Op-Amp / Floodlight Setup

A Picture of my Pressure Plate along with my water receptacle.

The Inner Workings of my Pressure Plate, The pliers provide spring tension which must be overcome by the water bottle, while the switch at the top controls both the pump and floodlight.

I made my Reservoir out of a cooler jug I had, the lid is ideal for routing the and minimizing the pressure it's weight applies to the pump's nozzle. 

I forgot to snap a picture of the pump before installing it so here is the stock image from Amazon where I ordered it from, along with a link to it's page.

4  

     Provide at least 2 videos of your setup in action, one being a failed attempt. 

     

 

A Demo of the Solar Panel/Op-Amp/Relay Setup

 

The workings of my Pressure Plate Explained

 

Dry Demo with a Different Pump

           

 

Complete Test Number 1.  AKA what happens if you forget to factor in gravity.

 

Complete Test Number Two.  Moving the Reservoir

 

Complete Test Number 3.  SUCCESS!!!!

    What failures did you have? How did you overcome them? 

    Initially I feared this project might have been a bit over ambitious when I submitted this week's pre-quiz the implementation actually went surprisingly smooth.  That being said I did encounter a few fairly significant hurdles.

    First was trying to figure out a way to move the water from the reservoir to the receptacle initially I planned a gravity feed using an electric motor to pull a stopper (See my initial Concept Drawing Below).  This proved to be overly complicated and potentially very messy.  My first thought was to find an electrically actuated valve but when I asked the technician if he had a suitable valve he didn't, but he did say he may have a pump.  I liked the pump idea so much I went home and ordered one off Amazon even before hearing back from the technician.  This turned out being a good thing because the pump the technician had proved to be far to require more amperage than our power supplies can provide.  The pump I did end up using was a 12 VDC aquarium/fountain pump.

Original Concept Art

    As I mentioned above I also ran into some limitations with the power supply in our labs.  Not only could the supply at my work station not run my first pump it also struggled to provide enough power simultaneously activate my relay and power the floodlight.  I overcame this by adapting a standard 12V 2A Power Supply, I had around from an old External Hard Drive.  By adding the stand alone power supply I not only solved the amperage issue, but also eliminated any issue me and Chris might have encountered sharing the power supply at our work station.

    The final major issue I encountered was water siphoning backwards from my receptacle back into my container into the reservoir.  This can be seen in my Complete Test 1 and 2 Videos above.  I initially thought I may need to install a check valve to prevent the backwards flow, but I was able to find a much simpler solution.  I adjusted the position of my receptacle on my pressure plate so that less water was required to overcome the spring.  I also moved the end of my hose to a higher position within the water bottle.  What this did was left a gap of air between the end of the hose and the water line when pressure switch actuates eliminating the siphoning effect.   As an additional bonus by moving the hose to the bottom of the bottle and restarting the pump for a few seconds the water can be made to siphon back into the reservoir making resetting the circuit much easier and less messy. 

    I am Looking forward to demonstrating the full circuit in class on Monday or Wednesday.  Enjoy the rest of your weekend and see you next week.