zr416
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Invention Idea

Postby zr416 » Sat Feb 17, 2018 9:19 pm

Our big eight grade project is an invention convention, where we have to think of solutions to problems. For my project, I wanted to do a fingerprint locker. I was wondering what materials would I need for that, and what experience would that require, software programming, coding, etc. Also as a back up I had an idea for a kinetic energy phone charger, would you be able to tell me materials I would need, and if I should have experience with computers for these kinds of inventions, or can I learn as I build- because I am a complete beginner when it comes to coding. The project is due in a month but I must submit my idea in 3days. Would you recommend going through with these inventions as a beginner or go with something more simple? Thank you!

bfinio
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Re: Invention Idea

Postby bfinio » Mon Feb 19, 2018 7:13 am

Hi zr416,

I'm not entirely sure what you mean by "fingerprint locker" - do you mean a physical lock that you can open with your fingerprint? There are electronic fingerprint scanners you can buy but building something functional with them would require a good deal of electronics and programming experience, so might be a little ambitious for a first-time project:

https://www.sparkfun.com/products/11792

If you wanted to, for example, do something with a fingerprint scanner on a smartphone, there is an app called MIT App Inventor that makes it easy for beginners to program smartphone apps (I'm not sure if it allows you to use a phone's fingerprint scanner, you would have to look around their website):

http://appinventor.mit.edu/explore/

For a kinetic energy phone charger - you could build one of those without any programming, but you would need electronics experience. We have a simple project that may be a good place to start - it shows you how to use magnets and a coil of wire to light some tiny LEDs. However, the circuit to charge a phone is more complicated and you would have to search around online for more instructions:

https://www.sciencebuddies.org/science- ... red-energy

Hope that info helps you get started.

-Ben

zr416
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Re: Invention Idea

Postby zr416 » Mon Feb 19, 2018 12:04 pm

Thank you!!!! :D

bfinio
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Re: Invention Idea

Postby bfinio » Mon Feb 19, 2018 12:42 pm

No problem! Don't hesitate to post again if you have more questions. If you are interested in learning to program there are a ton more resources online but I didn't want to flood you with links in my first response.

zr416
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Re: Invention Idea

Postby zr416 » Thu Feb 22, 2018 4:56 pm

Hi again, so we went through the links (thank you for those) and we decided that it was to complicated to use kinetic energy as a charger, so we decided to use solar energy. I was wondering if there would be a possibility we could put an electrical socket along with a USB port in one device, https://youtu.be/5HPm-Act2Zk, this is pretty much what we are doing but I was hoping to modify with the outlet idea.

LeungWilley
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Re: Invention Idea

Postby LeungWilley » Thu Feb 22, 2018 7:23 pm

Hi zr416,
I would recommend against adding this outlet. The solar cell design shown in the video have a number of issues (no power flow protection with diodes, etc...) that could be become a serious safety hazard with additional components like the outlet. Also, what will this outlet be powering? These solar cell (0.5Watts each according to the video) will get you 4.5Watts with the 9 cells in ideal sunlight. There's not many device that uses that little power. The closest thing might be an LED bulb but that's a DC device so you would be better off just installing an LED light without the inverter that changes the 5Vdc to 120Vac. (There are also losses in the conversion process so that will further reduce the available power.)

Good Luck and please let us know if you have any more questions!
Willey

zr416
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Re: Invention Idea

Postby zr416 » Thu Feb 22, 2018 9:46 pm

We are planning to use higher voltage solar pannels, would the outlet still work? Thank you!

LeungWilley
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Re: Invention Idea

Postby LeungWilley » Fri Feb 23, 2018 3:54 am

Hi zr416,
The higher voltage might help but it's more about the power output (wattage) of the panel. Also, with a higher voltage solar panels, you are going to need voltage regulator and converter to bring it back to the 5Volt that the USB port uses.
Good Luck!
Willey

zr416
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Re: Invention Idea

Postby zr416 » Mon Mar 05, 2018 9:08 pm

Do my solar panels need direct sunlight, or can i cover it with clear plastic as protection? Thank you!!

LeungWilley
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Re: Invention Idea

Postby LeungWilley » Tue Mar 06, 2018 5:06 am

Hi zr416,
Clear plastic should be fine as a cover but the panels' efficiency might go down very slightly depending on the grade of plastic amd how much reflection / refraction occurs within the plastic.

Good Luck!
Willey

zr416
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Re: Invention Idea

Postby zr416 » Thu Mar 15, 2018 4:16 pm

Hi, so about the solar panels, how much voltage would I need to power 2 usb outlets (DC-DC boost converters) and an electrical socket (only 1)? We are planning to use rechargeable batteries to power this, is that a smart way to go, or should we find another way to power it? Also, can I combine more than one solar panel for more voltage? And what is an output parameter, and how, if it will, would it affect our project? Thank you, and sorry for all the questions!!

LeungWilley
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Re: Invention Idea

Postby LeungWilley » Thu Mar 15, 2018 6:05 pm

Hi zr416,
It's no problem with the questions. That's what this forum is for :) (This is going to be a long answer though...)

The output parameters are the electrical characteristics of the system that you are trying to assemble. In your example, this would be the loads (the 2USB ports and the outlet) that you want to power, the run time for the system on battery, the charge time of the battery, etc...)

In order to do this design, we need to be a lot more thorough in defining what you expect out of this system.

To start, let's look at the 2 USB ports. There are different variant of this so you need to specify what you would like to be able to charge. Please take a look at https://en.wikipedia.org/wiki/USB. The most common USB version right now USB 2.0 (0.5Amps), USB 3.0 (0.9Amps), and Type-C (3.0Amps). (Your phone / electronic will tell you which version of USB port it has or you can look at the wall charger that comes with the device - the ratings will be printed on the charger.) So, as example, let's choose USB 2.0, the subtotal power required then is 5Volts * 0.5Amps = 2.5Watts.

2. For the 1 outlet, what voltage would you like this outlet to run at? (A typical outlet in the United States is 120V, 15Amps at 60Hz, while much of Europe and Asia runs on a 230V, 50Hz system.). Again, as an example, let's use the US version of the outlet at 15A. The power required would then be 120V *15Amps = 6000W. You could lower this power requirement by limiting what can be plugged into this outlet. As a side note, You will need a DC to AC inverter in order to power the outlet.

3. Let's assume you are using re-chargeable battery, you will then need to size the battery to give you the run time that you want. (If it's cloudy, snow, or you went indoor - how long should this system be able to run? 15 minutes, 30minutes? ) You will need to take the total load of the system so far and multiply by the runtime requirement to figure out what size battery you need to get. (Batteries are rated by WattHour or AmpHour-You can convert the Amphour to Watthour by multiplying by the battery voltage.)

4. Next, we need to look at the solar panels that charges these batteries. Depending on the type of batteries you select (such as Li-Ion, NiCAD, etc...), there will be different charging requirements. For this application, please google the term "solar battery charger" for a list of different options. Finally, once you define how much battery is needed, you can then figure out the size of the solar panel and their requirements.

Bottom line, we need to start with a list of the items that you want to be able to power with this device. Once we have that, we can start sizing and specifying the rest of the components. Just one final word of warning though, the AC outlet will significantly increase the cost and space requirements of this device.

Good Luck and please post again if you have any other questions.
Willey

zr416
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Occupation: Student

Re: Invention Idea

Postby zr416 » Sat Mar 17, 2018 3:22 pm

Hi (again) :lol:, so instead of an outlet, what if we use a flashlight. We were wondering if inserting an LED bulb would be a better idea, and if we could get an on-off switch for it (also what would the switch be called?). Is there a special bulb that is solar powered or would we have to attach it to our panels somehow? Also would the light bulb ever die?

This is our material list, would we need to change or add anything else?:
1) Usb dc-dc boost converter (2)
2) Solar panels (we aren't sure yet how many volts)
3) Zener diode
4) 47k resistor
5) 51k resistor
6) (presumably) 10-12 volt rechargeable batteries
7) Soldering iron
8 ) digital multimeter
9) mini LED lights (presumably) 120V
Thank you!! :D

LeungWilley
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Re: Invention Idea

Postby LeungWilley » Sun Mar 18, 2018 11:45 am

Hi zr416,
Yup, IMHO, the LED / flashlight, would be a much better fit for this device. Just a couple of clarification though, an LED is a DC (Direct Current) device. In fact, you should be able to use the same 5V USB voltage to power this light. However, please do note that most of the LED will have a forward voltage requirement of 2.5 to about 3.7V so you will need to design a voltage divider circuit. LED usually have a very long life, typically in the 30,000 hours to 40,000 hours range. Usually, other components will fail long before the LED.

Here's an example of an LED light:
https://www.mouser.com/ProductDetail/Lite-On/LTL17KTGX3KS?qs=sGAEpiMZZMtmwHDZQCdlqZICT%252bSaMZUBN7SS5xXRSR4AZ8svO2G8BA%3d%3d

In regards to the switch, I would suggest something like a "Rocker Switch" Here's an example:
https://www.mouser.com/ProductDetail/CW-Industries/GRS-2011-2018?qs=sGAEpiMZZMvEZpvz4iUm3t5I5IXx8x6Q

In regards to your part list, I would need to see the circuit diagram to make sure that you have all of the parts needed for this. At a minimum though, I would suggest adding the following to your list:
A. Breadboard - for prototyping the circuits
B. Solder
C. Blade connector and associated wire crimper
D. Wires (probably 22 AWG or larger (American Wire Gauge))
E. DC mini current clamp (This is an accessories for the multimeter so that you can check for current flowing to the device without breaking the circuit.)

Good Luck!
Willey


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