Question by CHATHUSANKAY | last reply
I want to power 3x 0.5W LEDs in series with 3x AA Ni-Mh batteries (input voltage will range from 2.5 to- 3.7 ). The total forward voltage is around 10volts, and the current of the LEDs is 150mA. I've tried using a Joule thief but it's quite inefficient, even with different transistor / toroid / resistor configurations (even with fast switching Darlington transistors) the maximum current I've been able to get at the LEDs is less than 100mA, and many energy gets lost in the process, it seems the resistor between the coil and the base of the transistor slows down the switching process and limits the current. I need a more efficient way to power the LED's, either an improved design or a LED driver chip. But trying to keep the efficiency rate around 60-70% or more. I have found a design that claims to be more efficient (see picture), but I'm not sure about if it will deliver 150mA.
Question by Victor805 | last reply
Most of the LED bulbs now sold as incandescent replacements have cooling heat sinks on them. If they have such great efficiency, I would expect minimal waste heat with no heat sink needed. Do they get too hot to touch as well?
Question by LongToe | last reply
if we design solar water heater by two paralel cover glasses. what is the function of the outermost glasses? ?
What is the best range between two glass covers (in mm)? how to calculate the efficiency of this SWH? this swh is length, width, height 137 cm, 126 cm, and 10 cm. thanks for the answers
Question by diaz.zahara | last reply
I need to make a joule thief type of thing that can up the power from a 0.55V source to a simple LED. I know that the joule thief is not the most efficient circuit which is why I am asking if you know of an efficient circuit I can use.
Question by physics_dude | last reply
First, I would like to say that I do not know if this is the place for this question, but: I have just heard of bitcoin mining and started to look into it. I have learned that pretty much the only way it is plausible is through the use of a machine dedicated to mining the bitcoins, not through using gpu's anymore apparently. But I have seen that these machines are expensive, so naturally I would want to build a DIY one if I started this. But are these dedicated miners even efficient? And what if they don't have the top of the line components? I tried to look this up myself but I don't really understand the hash rates of these machines so I don't know what is considered an efficient rate. And, in my current situation, I don't pay for electricity or internet so now would be an optimal time to do so and maximize profitability. So, do these dedicated miners work efficiently enough to make it worth while to build/buy one? Especially if I don't pay for electricity or internet?
Question by texpert | last reply
i.e. is a circuit with resistors much less efficient than having the correct voltage/current from the course? i'm thinking here mainly about dimmer switches and also parallel LEDs where each would need its own resistor. Cheers.?
Question by jamesjamesjames | last reply
Another interesting thing I found through research, a flaw in most over-under designs and pressurizing the stock, I have found that for every 90 degree elbow between the chamber and the barrel the resistance to the air is the same as adding 20 feet of straight pipe, this can be changes by using two 45 degree fittings put together to make a gentler turn or by using curved fittings instead of elbows, the gentler the turn the better. From this I have found that the simple straight cannon with the chamber directly behind the barrel as is shown in the picture below (please note this cannon is one I found from Google just to emphasize the point, and this is in pneumatics only). also to increase efficiency look at my other topic:https://www.instructables.com/community/best_chamber_to_barrel_ratio/(once again if you have found my research incorrect please tell me, I wont get fired up =)
Topic by cheeseboy | last reply
I need a high efficiency 12V DC regulator to supply my thermoelectric modules (they're very inexpensive so I had no choice but to use them). I found that the modules are most efficient at 12V @ ~7A each. I could use many 7812s in parallel but they are too inefficient and too much energy is lost to heat. Is there any alternative? Electricity bills are going up so it'd be very good if I can find an extremely efficient step-down or step-up regulator, short of using an expensive 'gold standard' ATX PSU (which are usually upwards of 500W so the power savings don't matter).
Topic by arikyeo | last reply
Right now, I am looking for schematics for the most efficient (1 cell and 1 LED) joule thief, to use as a durable reading light. I right now favour Quantstuff's 2 transistor SJT (http://quantsuff.com/LED2.htm) but I am not sure whether it is the most efficient. I've seen several others, but since they all claim to be equally as efficient, i'll have to rely on the experience of other tinkerers and hobbyists. So: what's the most efficient or high current or high voltage joule thief you know of? Thanks.
Question by .Unknown. | last reply
I am planning to make a small boost converter similar to mintyboost. I am using a boost IC that will give me about 92% efficiency with the voltage i have. The output is 5v at 500ma, and the input voltage is 2.4v. Would the ic suck up more than 500ma per hour from the batterys?
Question by astroboy907 | last reply
Is there any way to combine a Light Dependent Resistor or other light sensor with a Pulse width modulator to (energy efficiently) dim indoor lighting in the presence of sufficient natural light? Thanks!
Question by bbawco2 | last reply
What is the most efficient way to transfer lateral movement to vertical movement via a ramp. The following curve is equal on both sides of the apex, if that is the correct term. Is this the best way to transfer the movement to strait vertical or should something else such as a long start to the incline and then a sudden shoot up.
Question by jj.inc | last reply
Hi guys. When you use solar panels and have gadgets with different voltage requirements that you want to power up. I need atleast 2 different outputs, 5v and 12v , so which is most efficient , 12/15v panels that you regulate to 5v , or 5v panels boosted to 12v? is there any general advantage in either case and i,m talking about using cheap ebay switch regulators / boost converters, not anything expensive hi tech. regards
Topic by kristerh | last reply
I' been inspired by these bike lights from reelight.com. I have a set of these for my bicycle for reliable and very effective lighting. It's stated they are powered by "pure induction". There's got to be a way to harness the energy from both wheels to charge a USB device (5 volt) in the same manner. Instead of using a friction generation mechanism bike charger or bike generator.Any thoughts?
Question by rhow | last reply
we know that solar panel gives maximum power at particular voltage.which is a bit less then the actual rating of the panel. my aim is to get a constant voltage across the battery,okh. but can i do sth by which i can get such const voltage 4 which the power provided by by solar cell is maximum. i can introduce a microcontroller which will continuously check the voltage ......and itwill get stuck at dt particular voltage...but i am getting puzzled with dat,ne idea plz
Question by sumgupta89 | last reply
efficiency (not efficacy) of CPUs/computers? is all the power input technically converted into heat? Answered
It has recently been fairly hot where I live, especially in my room, where computer hardware seems to be increasing the temperature by a good 5-10*F over other rooms. This got me thinking, and was wondering if any computer engineers/physicists may know the answer to this one. If I am running a power-hungry intel CPU, coupled with RAM and maybe SSD storage (I wish!) is all the power fed into my system being converted into heat? In other words, if my rig consumes a good 250W-400W, and there are no transducer devices drawing power (LEDs or lights, speakers/microphones, monitors, motors, heaters, phone chargers, etc,) and all the energy is used for data collecting, and calculating, then is *ALL* the energy converted to 250W-400W of thermal energy (heat)? or do the data operations themselves in fact require energy and maybe entropy or something plays a role? where it would seem that 400W of input yields an apparent 399.981W of energy output + data.
Question by -max- | last reply
Hello All, I am using an 1KVA Voltage stabilizer for my Fridge. The power quality is really poor here in India, and these things are mandatory. I learnt the lesson hard way :-(.... Well that aside, i would like to know what would be the power loss or Extra consumption these devices use when regulating power. Actually,i could use a general lecture on how Stabilizers work!
Topic by bhvm | last reply
I am trying to make my own wind mill using a stepper motor, capacitor,led, and a resister. My problem is that my dad wants me to make it more efficient meaning making the led go brighter and longer. I curently have 11 capacitors in parallel ,one resister. what are some math equations i can use to find out how to make this more efficient and how do i use the problems?
Question by lookwhatjoeysmaking | last reply
I need a circuit that has a switch between 3 and 5 minute off times and a 3-5 second on time that repeats. It needs ot ahve an on off switch and be as as efficient and compact as possibly, and fairly easy to make. Thanks in advance for any help! I need to order parts for it, so the parts I need would be nice.
Question by aarroozz | last reply
I want to point out a solar to electric generation concept that has yet to be seen anywhere, even though it originated back during the Carter Administration's ERDA programs of the late 70's. I’m talking about solar power towers that convert solar energy into electricity at the hundreds of mega-watt level. While power towers do exist today, and the world currently does have a handful of them as shown in Fig-1, none use the Brayton Cycle nor can they boast an energy conversion efficiency at the mid to upper thirty percent level. A group of engineers got together at a think tank organization called Sanders Associates in Nashua, N.H., several decades ago, and designed a unique Brayton Cycle, 100 MW solar Power Tower concept for generating electricity. This was accomplished under ERDA (Energy Research Development Administration) who gave us a phase-2 follow-up contract that took our phase-1 design and built a working scale model at the 10 KW level. This model was tested at the Georgia Tech Solar Research Facility and "registered" ~37% electric solar conversion efficiency. The system used ambient air as its working fluid, and was to be located in open-spaced desert regions. Phase-2 was lost to competition using a closed-loop liquid sodium system that boiled water into superheated steam at 900F to run a turbine that generated ~21% overall electric conversion efficiency. Apparently, at that time ERDA would rather haul water out to the desert than use ambient air to generate electricity? The politics of their decision is beyond reason and clashes with improving the world’s development of green technology energy. ERDA shut out our better technological performer and safely locked it away for another day! ERDA's official reason for turning us down: "this technology uses excessively high temperatures (2500F versus 900F) that are dangerous to workman maintaining the equipment". But that was back in the 70’s, maybe we’ve learned to deal with high-temp heat by now? Solar Energy Concept Using Low Pressure Storage Our solar power tower would collect the sun’s energy by locating its ceramic heat exchanger on top of a tall tower as shown in Fig-1. The tower was located in the center of a field of active sun-searching mirrors (heliostats, Figure-2). These mirrors reflected sunlight onto our ceramic honeycomb heat exchanger, producing a concentrated flux intensity level that heated it to around 2500F. At the same time, low pressure fans generating only a few psi pressure would suck the ambient air through the honeycomb, heating it to just under the 2500F and then passing it through energy storage silos which stored the heat down to ~150F. We purposely designed the energy storage charging phase of our hot air system to work at only a few psi above ambient as a safety feature. The sun effectively acts as the combustor of our jet engine or Brayton cycle engine. Once the sun heats the air, it passes through heat exchangers consisting of a labyrinth of underground silos that are temperature segregated. These silos receive our 2300F airflow and cool it down to about 150F, transferring this heat into solid salt containers which turn to liquid once they have absorbed sufficient heat. Figure-3 is a schematic of this underground energy storage facility and shows the airflow being heated by a fully charged set of silos containing liquid salt-bricks. This airflow direction is reversed when we charge the silo’s salt-bricks. The bricks are kept in specially insulated, high pressure silos (located underground for added insulation) that store the heat energy at one atmosphere for later use. These underground silos act as our energy storage batteries, and when needed would discharge their heat energy accordingly into the moving airflow. This energy storage concept permitted the generation of electricity at night and during overcast days. Two sets of storage systems are required for continuous operation. One would be charging at low pressure while the other is discharging at high pressure through the Brayton engine to generate electricity. Electric Energy Generation at High Pressure Electricity would be created by turning an electric generator at high speed. The generator was turned by running a jet engine connected to it. The engine’s combustor for heating the air is effectively the sun, hence the name Brayton cycle for generating our solar electricity (Figure-4). The heat from the molten salt containers would increase the energy of the high pressure air coming from the compressor, and would then force it through a typical turbine that turns this energy into high rotational speed to run the generator and make electricity. Our solar jet engine sucks in ambient air using its compressor, as all jet engines do, and blows it through a series of silos at high pressure whose stacked bricks are held at different temperature levels. We start our airflow through a silo held as low as 150F and work our way up to ~2300F as we pass through our last, hottest silo which acts to complete the effective solar combustion process. This air preheating technique dramatically improves our energy turnover capability and allowed us to convert solar energy into electricity at near 37% efficiency. During our electric energy generation phase, the silos of our Brayton system requires operating at many atmospheres of pressure just as in any jet engine combustor using petroleum-based JP-fuel.
Topic by RT-101 | last reply
HOW TO PRODUCE MORE THRUST IN A REMOTE CONTROLLED QUADCOPTER ? 1]LONG PROPELLERS LESS RPM or 2]SMALL PROPELLERS MORE RPM
I ALSO NEED ANY RELATIONAL FORMULA BETWEEN LENGTH OF THE PROPELLERS , WIDTH OF THE PROPELLERS , RPM (rotation per minute) AND THE THRUST PRODUCED . ANY OTHER DETAIL ABOUT QUAD COPTER ( or any other flying vehicles ) CAN ALSO BE STATED. THANK YOU!!!!!!!!
Question by RAGHUL NM | last reply
I need a portable and efficient way to convert battery power (3 volts) to around 400 volts. I will be using alkaline batteries... This will be used to charge a high voltage capacitor bank.
Question by brooklynlord | last reply
I am planning to buy a modified sinewave inverter just to power some basic stuffs from a car, but one of my main problem is that i want to power 2 sensitive devices on the inverter. I have a 450W computer powersupply Will it run smoothly or will make hissing noise or will get fried after minutes of use same goes with a 19" inch LCD screen some help here would be much appreciated thanks
Question by ARJOON | last reply
We love barbecue here. Our way to do the barbecue is to skewer (spit) the meat together by a metal pin or bamboo pin. Normally we do it manually. Does anybody know if there is one more efficient method or some kinds of equipment we can use on the skewering?
Question by Steve Zhang | last reply
How to assemble a low voltage, variable speed electric motor in a school laboratory, and how to measure its efficiency?
For a high school physics project, I am doing an investigation on how does the density of the transmission fluid affect the efficiency of a fluid coupling. I am planning to use honey based transmission fluid with varying amounts of water to dilute it, and alter and manipulate its density. For the turbines (blades of the fluid coupling) I need to construct a low voltage electric motor with variable speeds using materials easily available in a school laboratory (though I can use some other source for my materials as well). I need to measure its efficiency. and by that I mean to actually compare the input and output energies (perhaps their voltages) using a low inertia dynamo as my output generator.
Question by diwakarchopra | last reply
Has anyone built an efficient rectifier before, from 220-230V AC to 12V DC as well as a 12V DC to 220-230V AC inverter?
I want to build a DC-AC inverter / AC-DC rectifying system. I want my inverter to convert 12V DC to 220V AC as efficient as possible and without to many components because i want to host my rectifying system in the same box as my inverter. my question is who has designed this two systems before separately of course with the least components and had an efficiency higher then 85%?
Question by FransN | last reply
I have two laptos that don't work and I want to make a tesla turbine out of one of the hard drives
Question by nerd7473 | last reply
For charging 6-module packs of NiMh Prius batteries (43.2v) at 1C.
Question by nedfunnell
What is the best way to power 25 red 3watt LED's and 5 blue 3watt LED's with a 100w LED constant current source driver? Answered
Please excuse me as my technical skills are not as good as I would want them to be :D So, I am trying to build a grow light with this setup: 1. 25 red 3Watt LED's - DC Forward Voltage (VF) : 2.2-2.8Vdc - DC Forward Currect (IF) : 700mA 2. 5 blue 3Watt LED's - DC Forward Voltage (VF) : 3.4-3.8Vdc - DC Forward Currect (IF) : 700mA 3.100W LED Constant Current Driver http://www.dx.com/p/waterproof-100w-led-constant-current-source-power-supply-driver-100-240v-146055#.VRh4f-HkWqg Power: 100W; Input voltage: AC 100~240V 50/60Hz; Output voltage: DC 8~12V; Output current: 8A (label on the box says: 12V 8A) What would be the best way to wire the LED's for maximum efficiency? I'm thinking somehow in parallel, but how exactly? Thank you.
Question by voltskaterzb | last reply
I've made a number of plans in 123d make, but there is so much empty space that becomes unusable for future projects. Isn't there some way to "condense" a .dxf so it has a smaller footprint? I don't care if the angle is weird or whatever, I just know that there has to be a far more efficient way to use up material.
Question by furrysalamander | last reply
I mean whats the diffrence? I have bunch of the transformers and another bunch of the fully electronic kinds? why use one or the other? heat, efficiency, weight. BTW can i put a stepper motor to a 12v side of the transformer and maybe get some 110v on the other side or thats sounds crazy? thanks Al
Question by celalboz | last reply
For a while now, I have been trying to build a thermoacoustic device with the following specs: -Can run with a temperature difference at around 100 degrees Celsius (ice on one end, boiling water on the other end, but it won't actually work with water) -uses normal air for the working fluid -constructed out of available household materials (or anything I can find at a hardware, office, or similar store) I have tried jamming coffee stirrers in a PVC pipe with copper wire serving as the heat sink, alternating layers of foil and two-sided tape, and for the third & recent attempt, newspaper jammed between two peg-boards (untested, but unlikely to work).
Question by Michael_Everett_Feder | last reply
I have 4 decent CIS solar panels that, in series and in bright sun, will give ~16V, and can offer ~ 200mA shorted. However, if shorted, the voltage obviously sags to almost 0V, so basicly no power is delivered based on the fact that V*I=P at the other extreme, there is almost 4V open circuit, but essentially no current flow. Again, 0W of power delivery. The voltage and current figures above are just memory and I did log the data at various resistances awhile ago. My intention is to charge 3 lithium batteries in series to 12.6V, that will then feed power to a modified car charger (basic buck circuit for downconverting 9V-18V to 5V) Since the current is so low, can I maximize efficiency by connecting the cells directly to the battery pack without any additional circuitry other than a blocking diode? Or in order to speed up the charging do I need to add some complex control circuit that will intelligently match the impedance? If the battery charging speed is based on current, does that mean a direct connection is best?
Question by -max- | last reply
Since summer has started, now my CPU temperature goes very high and the computer shuts down. The normal CPU temperature is above 75 Degrees. I do not have AC at home. Is there a way to cool the cpu with home made things or something easily available and cheap / inexpensive? The PC lay flat with it's cover open, and the ceiling fan at full speed. I do not run hot but the poor cpu does at above 75 degrees still. What can I do about it?
Question by rseni | last reply
I was hoping someone could tell me how a jet engine has to be designed to be efficient using hydrogen as fuel? what are the pros and cons of this option concerning fuel efficiency and power created? any information on this would be helpful.
Question by christian2gothic | last reply
I've been thinking, which, for me is strange. What's stranger, i've been thinking about saving the planet. I don't believe that global warming is solely the fault of man and his machines, nor do i believe that we're all going to fry in a ten-thousand year summer, but that's not the point of this forum, and i'd appreciate no comments labelling me as a communist, or a planet-hater. What i had in mind is a new system of lighting. Say i took some LEDs (lets say 16) and connected them in paralell, and attatched them to the appropriate power source, would they be more or less efficient than a tungsten filament lamp? As for aesthetic considerations, to simulate natural sunlight during winter months, one could add blue or yellow LEDs to tune the shade of the light. Would this idea be more efficient than the lights we have? (i avoided mentioning those energy-efficient lights because they're not really that efficient, and give crap light.)
Topic by Vendigroth | last reply
I've been looking into HHO units and the most efficient voltage is 1.5 VDC but the units pull 30 Amps. All the converters and modules seem wasteful while I feel there is a direct way to create this supply with minimal loss from battery supply. Resistors seem to be the most efficient but what resistor can turn 12V into 1.5V while delivering 30 Amps without burning something out. I'm contemplating a bank of resistors all on separate leads and tied together in a parallel combination so the 30 Amps are split along many lower amp rated resistors. I just don't know enough about DC conversion to know if amps will become volts or just get lost to heat dissipation. An HHO unit relies on the highest efficiency current supply to perform correctly and save my gas. The units are out there but not this fine tuned system I want to build because 1.5V at a 30 A draw from a 12V car battery is hard to do without wasting the gas in just converting the ideal power supply. I've heard talk of using diodes as well. Is a diode or resistor setup more efficient than a PWM? Could I combine diodes and resistors for better efficiency? I've been searching the web for info but it just confused me more as nothing I've read comes anywhere close to what I'm trying to do. Those I've read about that try to build the most efficient power supply end up burning up their components by pushing them too hard while instructing others to do the same. There has to be an efficient way to create that ideal supply current without much loss. Could it be run straight off my alternator since it produces AC before the voltage regulator converts it to DC or would a second regulator just waste more current than resistors and diodes from the 12V battery? Any advice or info would be greatly appreciated.
Question by bmac30 | last reply
I know it would not be 100% efficient, or even close for that matter. But I was wondering how much battery life could be "recycled" by directly projecting the light from the flashlight onto the solar panel(s)? Say at a 45 degree angle beneath the light. Obviously this wouldn't be a high output LED, and another question at that.. Would a Red LED be more efficient or would the PV cell not do so well with Red LED? Thought this would be a neat idea even if it would only recycle 5-10% battery life. I would love for someone to implement this idea into a project and see how efficient it is.
Question by xSoFx | last reply
I am trying to get a sensor to close a switch, but the output off the sensor is 120V AC, and that would blow my switch. Upgrading the switch is not an option, so I need to step down the volts (and most likely amps) to an acceptable voltage. I'm thinking a concept similar to a plug in wall transformer. Any ideas?
Question by spacecase544 | last reply
I have about 100 solar panels of 53watts from Arco solar about 15-18 years old and were in working up to five years back but since like 2004 or so are in a junk yard now I want to buy these but first I have to check min efficiancy as I am a instrumentation instructor in a technical Institute so, I can under stand your answer very well tell me in detail. also how can I draw IV curve for above with coventional tools like DVM some engineered load or so.
Question by emadjohar | last reply
How do I efficiently design an electrical system for an electrical motor run by saltwater fuel cells?
I am designing, building and testing an electrical system that runs off of saltwater and powers a buggy-like vehicle. My dilemma, is figuring out how to regulate the unsteady output of electrical energy into the electrical motor. I'm trying to figure out the most efficient type of electrical motor to use, only knowing I need 5 hp. How can I take the inconstant energy flow from the many energy cells, regulate a constant flow into the electric motor, and charge a separate battery with the excess energy, to be used in case of "emergency"?
Question by lhollar1223 | last reply
I want to do my B.E. project on the topic- "Adsorbent for waste water treatment," please suggest naturally available adsorbents which are cheap and easily available
Question by Deepak91 | last reply
I know how to calculate resistive losses, but do different types of resistors have different amounts of losses (power in vs power-out, in watts) From my own observations, connecting a 10 ohm resistor across a barrey will cause significant heating in both the resistor and battery, and cause the wires to get warm. All of this is resistive loss, but when I exchange the resistor for a 10k resistor, there is virtually no heating at all. What if I use a 0 ohm resistor (direct short). The only thing getting hot would be the power supply, due to internal resistance. Does this mean higher resistance is less lossy and by definition, more efficient, or is this simply due to the fact that there is less current flow, and less power loss, and efficiency (% of power loss) With an ideal constant current source, will the losses though any resistive load be equal? ( X amount of watts lost/dissipated @ 1A) Is it possible to limit current like a resistor without losses? (I know PWM techniques are more efficient, but I want actual resistance rather than chopping current flow and filtering with an inductor/capacitor RC filter)
Question by -max- | last reply
I don't know if you heard, but the ball that drops in Times Square every new year was energy efficient this year. It was twice as bright, but only used as much power as ten toasters. How do you think they did it? I'm thinking all LEDs. It was a neat thing for them to do, regardless.The following picture is from the Associated PressUPDATE: T3h_Muffinator looked it up on wikipedia. They switched to LEDs this year. Link
Topic by Weissensteinburg | last reply