Thanks for your ideas, but I think you really wrong abut the capacitor.I think you are missing the basic problem. If the converter does not get enough voltage from the pulse it will not turn on. If this happens all of that energy is lost forever, so you want it to turn on at as low a voltage as possible. Once it turns on the capacitor makes no difference. It will stay on as long as it has enough voltage , then it will shut off. You cannot get more out of it than you put in. Please show me where I am wrong.
Looks good, but I would have to assemble a PCB or carry a breadboard in my bike's breadbasket on my errands at least more than once. No room for the groceries. In this day and age, some worried people would think I am carrying some hi-tech bomb in my basket!. What do I do, disconnect it and put it into my purse before I enter Walmart? What might my girlfriends think?Somebody here has a signature line like, "One measurement from a real test is worth a hundred theories."
The way I put it is, "Electrons can't lie." Go make the electrons jump through the circuits and they will tell you the answer.
Looks good, but I would have to assemble a PCB or carry a breadboard in my bike's breadbasket on my errands at least more than once. No room for the groceries.
That's what the Pope said to Leonardo D. and Galeleo G. , but one of them and his boyfriend carried the Mona Lisa around with them a good part of their lives.OK. Still in the theory stage after 5 days...after at least 3 people have told you to try a different approach. This discourages us.
And you think you're a match for them?That's what the Pope said to Leonardo D. and Galeleo G. , but one of them and his boyfriend carried the Mona Lisa around with them a good part of their lives.
I find a specially designed/modified generator a lot more practical than the options you've been studying so far. The trick would be to make it as frictionless as possible and avoid direct contact with the tire at all costs, since it would be too high a source of friction for you to pedal comfortably. Also, doing the math for a generator should be a lot simpler... but I suggest you do the math in retrospect, by first building the contraption and making actual measurements that could tell you the system's overall efficiency...or I could fasten the coil of a 48V relay to my vise and with the help of a small motor with a brass rod soldered or superglued to its rotating shaft, attach thereon its end a niobium super magnet to twirl so close but not touch.
Yes. of course you need to match the load to the generator in either case. It would not like to discharge the cap into a short either. You need to set the current so the input to the boost regulator looks like 150 ohms. Then you will transfer the most power.Thanks for your ideas, but I think you really wrong abut the capacitor.
Again, the power stored in the capacitor is C*V*V/2, so available power for the converter increases with the square of the startup voltage. The larger the capacitor, the longer the converter can deliver its intrinsic current-limited pulses before the capacitor is discharged below the .3V UV cutoff voltage. The converter operates a >1.5MHz, so all these pulses are completed in less than a few mSecs, depending on the size of the storage capacitor.
Right now, I have 1500uf. So it works like this, energy is somewhat slowly built up in charging the capacitor, the capacitor is rapidly discharged but is able to deliver power until the cutoff voltage of the MCP1624 (.3V) is reached.
If no capacitor was used, the 150 source resistance of the generator would face almost a short circuit. At best, the current in the switching inductor could not rise above approx 20mA with at peak, .9V of voltage across it.
That will be extraordinarily difficult. The generator output will depend heavily on the magnet field strength and shape, the air gaps (which will not be identical), the inductance of the coil, and probably a few more things I can't think of. The results you measure will depend on the properties of the rectifier and the load placed on the DC side. In fact to be at all useful, you'll need to map out the voltage and current over a wide range of load impedances. Everything you measure depends heavily on rpm, so you'll need good control and measurement of that.The answer can be found if I just simulate the output of the generator.
You're right... but I'm under the impression that the OP is still considering all viable options... I think she wants to fundamentally understand every aspect involved in her initial idea, with a complete registry of calculations and conceptual engineering... but there are situations in which doing this before building the actual device is more time consuming and expensive in terms of the effort involved... any experienced engineer knows that... I guess we're all waiting for her to reach the "aha moment" and move forward.The TS has derided EVERY suggestion put forth, why is anyone still coming back for more of the same?
I need to get my eyes checked again.I should have the capacity to easily stimulate what goes on between my legs as I roll down the road.
Thanks for analysis, I studied and thought about what you've said carefully.I find a specially designed/modified generator a lot more practical than the options you've been studying so far. The trick would be to make it as frictionless as possible and avoid direct contact with the tire at all costs, since it would be too high a source of friction for you to pedal comfortably. Also, doing the math for a generator should be a lot simpler... but I suggest you do the math in retrospect, by first building the contraption and making actual measurements that could tell you the system's overall efficiency.
A valid point... but how exactly do you intend to generate the energy that you plan to harvest in the first place? If the method chosen for this purpose is not good enough then it won't matter if we're talking about trunk or tail...Thanks for analysis, I studied and thought about what you've said carefully.
But I see that you are looking at the wrong end of the elephant, as one blind man said to another.
The idea in question is about energy harvesting of energy already delivered to the input of the boost converter, and duplicating the generator exactly on my workbench does not offer any way to optimize harvesting, which size capacitor is best for this, what startup voltage is optimal. I only have to create various pulse train scenarios to charge the capacitor to some value that could be studied for energy harvesting to optimally deliver the charge in the capacitor(P=C*V*V/2) at a particular Vstartup of the bo0st converter.
Thanks for your comments, I truly appreciate all of you for your patience with me and the gift of your comments and analysis.A valid point... but how exactly do you intend to generate the energy that you plan to harvest in the first place? If the method chosen for this purpose is not good enough then it won't matter if we're talking about trunk or tail...
Ronv, thanks again for your analysis. I have thought about the results you show, but you fail to try to examine the condition where there is no 150 ohm resistor in parallel with a 4500uf (value corrected) capacitor that simply wastes any power delivered to the energy storage capacitor.Actually, I was wrong about the capacitor. It makes it worse because of the higher current thru the diode to charge the cap increases the loss in the diode.
The simulation below shows the results of the 2 ways.
by Jake Hertz
by Aaron Carman
by Don Wilcher
by Aaron Carman