I want to add, I wasn’t originally thinking of a web page. I was thinking that the microprocessor would read the sensors and write their values to a wireless output device. Ethernet or Bluetooth, it doesn’t matter

But the web page approach doesn’t require any programming on the phone. Which may be an advantage.

 

You are right, I totally agree with you. No point in doing this yet I have to do it...

Nothing like a lazy professor wasting student's time.

 

In order to graduate, me and my friends took upon ourselves a wireless RF energy harvester project.

Uh-oh.

Our objective is to receive RF energy and then turn it into useable DC energy.

Forget "useable" energy; if you're clever and careful and lucky, you might end up with enough energy to actually measure with sensitive instrumentation.

This energy will then be deposited in a li-on battery.

No way. You won't even get enough energy to overcome the battery's internal self-discharge rate.

What @Papabravo said above in post #2 is absolutely correct:

Maybe you could improve your results if you did your experiment underneath a 50,000 watt clear channel AM transmitter antenna.

True; if you can arrange to demo your energy harvester in close proximity to a powerful AM radio station, you probably should be able to get enough energy out of it to light a sensitive LED. Anything more than that, is doubtful.

 

This is troubling news.

 

Thanks guys, I read them all. I really appreciate the amount of replies. I will be posting further advancements. I will be discussing this with my teammates for a time...

 

Thanks guys, I read them all. I really appreciate the amount of replies. I will be posting further advancements. I will be discussing this with my teammates for a time...

Good plan. I hope something positive comes about from this exercise.

 

Good plan. I hope something positive comes about from this exercise.

Thanks for the optimism, I needed that

 

Thanks for the optimism, I needed that

Research is a critical part of discovery

 

Nothing like a lazy professor wasting student's time.

It's not a waste of time if they learn something from it. Just from this thread I think they've learned a bit: researching available options, discussing feasibility, etc.

 

Old guy here. We used to make crystal radio sets using a germanium diode(low forward voltage drop) and a tuned circuit to listen to am radio via a crystal earpiece. It needed a good aerial though so it is possible to get some energy. Your problem is that it can't supply enough to transmit. You could get the receiving device to supply the energy. I am thinking of something that works like an rfid tag. Your device opens and closes a switch on the tuned circuit and the receiver senses the tuned not tuned condition, sending information as morse code. It would be very short range but it would qualify as wireless. Just a wild idea to show that you've considered everything. good luck.

 

You do have quite a few challenges ahead of you however, does your professor state that the energy that you harvest must be used to power your data collection and transmitting circuitry? If not, that part of the project is fairly cut and dry. The challenge will be storing the harvested energy in the battery. As mentioned in a previous post, overcoming the batteries internal resistance in order to effect charge will be tough. If you are not given any requirements for the battery, other than chemistry, then research the various external factors that affect the batteries internal resistance and optimize the system to take advantage of what you can. In essence, if the specification for the task is vague, as it appears to be, then set the task up to make it as easily achievable as possible. It will still be difficult but achievable. Good luck!!

 

Energy harvesting is becoming more of a thing and its interesting to hear this take on it. I would look at something like a Joule Thief or, an IC energy harvester and get some idea of how much energy you can harvest. Working on a similar project of harvesting tree energy we found that there was really not enough energy to even have an active component in the circuit. We determined it was required to complete this with passive components.