Hi,
Why is it impossible. I think you are wrong. Maybe if I use a low power 555 I may use the energy in the cap to build a monoshot circuit?
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- but to give a pulse based on the charge stored on a capacitor how about the standard beam robotics solar engine?.Hi again,
Ok this problem is becoming more clear as time goes on
Part of the confusion was in the waveshape that was posted, which clearly shows a VOLTAGE waveform, and there is no limit to how much energy a voltage can produce. Later, we found that there was a series resistance but that combined with the voltage source and a capacitor meant that we would loose half the energy just in the transfer alone without even going any farther, which started to make this project's goal look rather bleak.
Now finally we are getting the full story. It's not a voltage source per se it is a coil that produces energy based on the generator effect when something magnetic passes by. This is entirely different than just a voltage source this is a physical device that produces energy. This allows us to model the energy producer to some extent and come up with a theory of how this HAS to work. We can later render that theory into a practical circuit that will behave similar to theory but with some losses.
The theory of operation would go like this:
The coil is modeled as an inductor with some initial energy storage. At t=0 we want to start to transfer that energy to another storage device in a form which would allow us to again transfer the energy to a third as yet unspecified device. But since the original question called for storage into a capacitor and assuming this is adequate for now, we'll go with the capacitor storage and leave the rest for later.
The first problem we encounter is that if the coil is connected directly to the capacitor the current goes negative and this will act to reduce the energy stored into the capacitor, so the coil current has to be rectified first. Eric's circuit accounted for this already as he was able to see past all the confusion about the 'voltage' source
Once rectified, most of the energy will transfer to the capacitor because it is being converted from a current source to a voltage source, ie a true power conversion, and a true power conversion allows high efficiency. The only remaining problems then are the devices that will be used to accomplish this should still have as low resistance as possible to prevent high energy absorption. To get low loss we would like to be able to use a synchronous rectifier so another question that comes up here is how often will the coil contain energy, that is, how often is it energized.
Eric's solution was to use a transformer instead which makes the voltage drops of the rectifiers look less significant, and a transformer is a true power converter so we would see only the loss of the transformer. That's not too bad, but i wonder what kind of transformer we would be able to design to be able to handle this kind of signal without requiring excessive startup current and be able to handle the very low frequency required. Perhaps Eric can come up with a solution for this.
In any case, we need power for generating the output pulse (although we still dont know what kind of pulse this is to be) so we need energy storage for the circuit as well as for the output pulse. This is a little more difficult but if we can tap off some of the energy we can use it to run the circuit and make the circuit as efficient as possible for low loss. We might also use some of this energy to run the synchronous rectifiers.
It would also help to use a double coil, where the coil was wound bifilar with a center tap. This would reduce the required rectifiers to 2 and thus avoid another rectifier voltage drop.
We would also need to know what kind of device this energy is to be transferred to. "Energy in the form of a pulse" has to be specified as either current or voltage or power.
So in the end we see this is not that much different from a transformer. The transformer transforms energy from one form to another and although it has some loss it still provides a much needed functionality.
I still think we're all blindly guessing
You can't get right to zero volts because energy can only be extracted if there is a flow of current from the cap to an external device; and that would require the voltage of the external device to be negative. The negative voltage would require another power source, which you say you don't want.
