The cheap flashlight had a rather small (0. 22 Farad) capacitor for energy storage - not very much energy, really, approximately 6. 6 Joules maximum or less than 1/1000th of what a single AA alkaline cell contains! Being a standard `super cap` its internal resistance was quite high (10`s of ohms) which meant that a large percentage of the energy dumped into it during charging
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and that extracted from it to run the LED was lost as heat - not much heat, but heat just the same. A switching converter to run the LED. The LED didn`t even begin to light until 2. 7-3. 0 volts or so appeared across the capacitor and it isn`t usefully bright until there is 3. 6-4. 2 volts available which meant that a significant portion of the energy in the capacitor (all of that at voltages of 3-ish volts and below) was unusable. A simple switching converter would allow both extraction of that additional energy as well as regulate the LED`s current so that its brightness was more consistent over the entire charge range and, in theory, could also be adjusted upwards or downwards as necessary. The efficacy of trying this with a capacitor of high internal resistance would probably be dubious. One of the conclusions in this earlier article was that the back-and-forth shaking motion wasn`t a very efficient means of generating electricity - both in terms of expended muscle energy (since you have to move and stop the entire mass of your arm!) and compared to a conventional crank-type generator - and it would necessarily be larger and heavier in order to be more efficient. By using a conventional spinning generator and gearing up rotational speed, one can more-efficiently rotate a smaller magnet faster in a larger number of poles with a motion that requires less human effort. What`s more, a crank-type generator is quite...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
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