Red Knights for Hope was an activity at school where the objective was to create a water purification system for third world countries that lack fresh water. I created the design and most of the construction of the electrical system. Here is a video describing what Red Knights for Hope.
How It Works
The water purification is electrolysis based so when sodium chloride is fed into the 'electrolysis chamber', the electricity breaks down the sodium chloride into chlorine gas, which is then dispersed into the water that is flowing through the system. the chlorine kills off any bacteria the water contains. So for the electrical, our goal was just to make it as simple as possible. Initially, I designed two systems that would allow them to pour water and the system would start up, but it was later decided that it just wasn't feasible with the resources they would have in these third world countries. Thus, we created a simple system that is essentially a separate electrical powerhouse with outlets that they can plug the purification system. All you have to do then is flip a switch and it will start up.
This was my initial design that allowed the system to initialize when water is poured in the system.
The water purification is electrolysis based so when sodium chloride is fed into the 'electrolysis chamber', the electricity breaks down the sodium chloride into chlorine gas, which is then dispersed into the water that is flowing through the system. the chlorine kills off any bacteria the water contains. So for the electrical, our goal was just to make it as simple as possible. Initially, I designed two systems that would allow them to pour water and the system would start up, but it was later decided that it just wasn't feasible with the resources they would have in these third world countries. Thus, we created a simple system that is essentially a separate electrical powerhouse with outlets that they can plug the purification system. All you have to do then is flip a switch and it will start up.
This was my initial design that allowed the system to initialize when water is poured in the system.
Below is the iteration 2 design that starts up based on a pressure differential (according to Ideal Gas Laws, when a liquid turns to gas, pressure increases).
- The Force Sensitive Resistor (FSR) will increase in resistance, ergo increasing the voltage output of the voltage divider network (FSR & R1)
- The operational amplifier acts as a comparator here and will output a signal if the output voltage of the voltage divider rises above the threshold voltage or trigger point
- The threshold voltage simultaneously changes depending on Vout and therefore the FSR resistance - For example, say the Utp is 1v and the Ltp is -1v. If the voltage output of the voltage divider (FSR and R1) is greater than 1v, Vout will go HIGH and the threshold will change to -1v. So in order for the system to shut down, the output of the voltage divider (FSR and R1), must be below -1v
- This is called a Schmitt Trigger and is used to prevent rapid switching from electrical noise. It makes the system a lot more stable
- So from there, when Vout is HIGH, it will switch on a MOSFET which connects common to the relay coil, which then supplies power to the port
- The Force Sensitive Resistor (FSR) will increase in resistance, ergo increasing the voltage output of the voltage divider network (FSR & R1)
- The operational amplifier acts as a comparator here and will output a signal if the output voltage of the voltage divider rises above the threshold voltage or trigger point
- The threshold voltage simultaneously changes depending on Vout and therefore the FSR resistance - For example, say the Utp is 1v and the Ltp is -1v. If the voltage output of the voltage divider (FSR and R1) is greater than 1v, Vout will go HIGH and the threshold will change to -1v. So in order for the system to shut down, the output of the voltage divider (FSR and R1), must be below -1v
- This is called a Schmitt Trigger and is used to prevent rapid switching from electrical noise. It makes the system a lot more stable
- So from there, when Vout is HIGH, it will switch on a MOSFET which connects common to the relay coil, which then supplies power to the port