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# i have made a windmill thrw my car's fan motor and directly connctd to the led but it so deem any more crct ndd pls hlp Answered

pls help for circuit

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## 10 Replies

MahavishnuMan (author)2009-09-29

Perhaps (at the expense of coming off a troll) you could try spelling tutorials and typing lessons, both of which are free. I won't harp on this as much as others may, as it sounds like you might be doing this for a school science project, but clear communication will be the key to your bright future.

If I understand correctly, you are using the car fan motor as a DC generator to power an LED. There are several variables to consider here, and all of them are important to a successful circuit here.

First, if it doesn't light up no matter how fast the blades turn, you may have the LED connected backwards. LED stands for "light-emitting diode", and a diode only allows current to flow in one direction. Be careful with this, as too much reverse current will blow the LED.

Second, the fan may be somewhat inefficient. In a car, the fan spins rapidly due to the fact that it is supplied with 11-15 V. However, the speeds gained from wind will be a small fraction of this. Typically, an LED has a forward voltage of 3 V, so in my estimate the fan may need to spin anywhere from 200-500 RPM to generate this voltage.

The way the blades are designed aerodynamically, the weight of the blades, and the motor itself can be at fault here. Maybe using a different motor with lighter fan blades would be more productive.

You also might try adding a Joule thief to the circuit. If this is for a class, be sure to learn how a Joule thief works so your teacher can give you credit for research.

shivi_dubey02 (author)2009-10-09

thankyou sir my english is not so good  will u please suggest me which motor i have to use for led

MahavishnuMan (author)2009-10-09

It might be difficult to recommend a single type of motor, although I can at least point you in the right direction.  You'll want a motor that is rated at least 3 VDC; more voltage means it will light at a lower RPM, but may be more difficult for wind forces to turn.  Look for a motor that feels easy to spin - the less mechanical resistance, the better.

There are also a few things you can try to increase the output of whichever motor you use.  The first I can think of is by using a Joule thief circuit.  A Joule thief is designed to store weak electric currents until enough is present to light the LED; at this point, it discharges and then starts accumulating more electric charge.  Despite a slightly lower efficiency, a Joule thief can use a far lower voltage than what is normally required to light an LED.

The second option might be to use gears between the fan and the motor; with a large gear on the fan and a smaller gear on the motor, you may be able to drive the motor faster than what the fan would directly impart.  The only caveat is that a gear driven motor may require more torque, thereby making it harder for faint wind to drive the fan.

I hope this helps - keep us posted.

jtobako (author)2009-09-27

Try spell-check or your english teacher. What I got out of this is that you hit a windmill with your car, a part came out of the engine and hit you in the head, concussing you and now you hear crickets. I sugest you listen to the paramedic and go to the hospital with them and not try to drive yourself.

brokengun (author)2009-09-27

Granted your question does have terrible word (or should I say letter) choice. However, I think I understand what you are getting it. My question to you is: Have you modified your car alternator at all to charge at low RPMs? Most car alternators charge at a much higher rpm than a typical windmill can achieve (without gearing). You might need to add more magnetic material and possibly rewind the stator coil depending one what you want to do. If you are using the fan from a car, then I assume it has more than 2 or 3 blades and this will probably affect performance as well. More blades tend to having even lower RPMs but provide more torque.

seandogue (author)2009-09-27

Ok. ima prdy gd w/txtmsg gbldygk, but really...please use full words. This isn't a cell phone and your query sounds like gibberish

frollard (author)2009-09-27

gbldygk. BEST WORD EVAR. I lolled. My coworkers looked at me in puzzlement. I 100% agree. Take the time to put effort into asking a question, let alone researching, and results will flow in.

seandogue (author)2009-09-27

wut dint thy unrstnd wut gbldygk meens? ;-)

seandogue (author)2009-09-27

btw is thru nt thrw

steveastrouk (author)2009-09-27

Have you run out of keys on your keyboard ? I can't understand a word. Try using some vowels ?