# What can I light up with 5 mW?

Discussion in 'The Projects Forum' started by fluttermanman, Mar 30, 2010.

1. ### fluttermanman Thread Starter New Member

Mar 30, 2010
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I have 5 mW of power available from a wind energy harvester. What can I light up to demonstrate that my harvester works? Most LEDs seem to have forward voltages in the 1-10 V range, and I'm nowhere close.

A link to a potential product for me would be extremely helpful.

Thank you

2. ### Audioguru Expert

Dec 20, 2007
10,605
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5mW is a very low power. We don't know if the voltage is a few volts to dimly light an LED.

3. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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nano motor is an idea

4. ### fluttermanman Thread Starter New Member

Mar 30, 2010
10
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Let me modify my query:

What is the least amount of power that I will need in order to initiate a physical process (e.g. light up, cause to rotate, etc) anything visible to the naked eye? I have a device that outputs 5 mW, and I have no access to external power. If I'm going to go up onto a stage to show people that this device works, what can I use to show them that there is indeed some power there?

Is it possible to store energy from such a low-power output device?

5. ### KMoffett AAC Fanatic!

Dec 19, 2007
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What's the voltage output?

Ken

6. ### Audioguru Expert

Dec 20, 2007
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5mW into a 1.8V red LED lights it with 2.8mA so it will be clearly visible.

You keep talking about 5mW but we must know what is its voltage when it is loaded with 2.8mA.

7. ### fluttermanman Thread Starter New Member

Mar 30, 2010
10
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RMS Voltage for signal = 200 mV
Inductive coil resistance = 8 ohms

A red LED should do the trick?

8. ### Audioguru Expert

Dec 20, 2007
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A red LED needs 1.8V to 2.2V. It won't do anything with only 0.2V.
I don't know anything that will show something when it is fed only 0.2V.

You forgot to say the frequency. A transformer can increase the voltage to anything you want and light an LED.

9. ### retched AAC Fanatic!

Dec 5, 2009
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Even with a little model motor and a 3 inch plastic prop, im getting greater power.. Is this a micro/nano harvester?

You could dump the POWER (big letters) into a capacitor for a few months and get some useable juice. (Maybe not that long)

Last edited: Mar 31, 2010
10. ### KMoffett AAC Fanatic!

Dec 19, 2007
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An analog meter.

Ken

11. ### Audioguru Expert

Dec 20, 2007
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When an analog meter is on a stage then the audience will not see its tiny needle move.

12. ### KMoffett AAC Fanatic!

Dec 19, 2007
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A video camera pointed at the meter and a monitor pointed at audience.

Ken

13. ### fluttermanman Thread Starter New Member

Mar 30, 2010
10
0
Yes, it is a microharvester. It uses membrane oscillations to accelerate the magnets; wind induces the vibrations in the membrane.

Peak frequencies in my frequency analysis are anywhere from 5-50 Hz. It's a very complex motion.

I'll see what voltages I can get out with a smaller wire gauge (48) and a bigger coil spool. Also, I'm using NeFeB magnets. Know of any stronger, relatively cheap permanent magnets?

I obviously can't afford significant losses. What kind of efficiencies could I expect from a well-designed transformer?

Thank you all for your help.

P.S. For some background, I'm working on a substantial modification of this sytem: http://www.popularmechanics.com/technology/industry/4224763.html. The "power conditioning unit" mentioned at 0:59 is what's giving me trouble.

Last edited: Apr 1, 2010
14. ### fluttermanman Thread Starter New Member

Mar 30, 2010
10
0
In case anybody's working on a similar project, the solution to this problem was embarassingly simple: increase the number of turns per coil by reducing wire size (increasing wire gauge). With a 3,000 turn inductive coil, I am now able to light up several LEDs in parallel.

15. ### fluttermanman Thread Starter New Member

Mar 30, 2010
10
0
In case anybody's working on a similar project, the solution to this problem was embarassingly simple: increase the number of turns per coil by reducing wire size (increasing wire gauge). With a 3,000 turn inductive coil, I am now able to light up several LEDs in parallel.