Amplifiying Millivolt to Volts

Sorry guys I just barely figured out that it's not amplifying it power converting i'm really sorry.

This is sounding an awful lot like perpetual motion.

What power levels do you expect to be able to attain? How? If you think you can get more than a few milliwatts from the ordinary ambient environment with something simple like a wire antenna, how is it that you and your friends have not burst into flame walking around in that same environment?

There are some ambient energy harvesting technologies out there, but they're grabbing milli- or micro-watts, and they're doing it because the civilized world is saturated with radios these days. I suggest that you do a web search on that.

You mentioned "amplifying" this voltage to 110V AC. That implies that you think you can get way more power than will ever be available just by sticking an antenna into the air -- unless people happen to be bursting into flames through inductive heating when they walk through the area.

Feel free to actually give us some useful detail, but before you do that I suggest that you get onto Wikipedia and study the first two laws of thermodynamics.

In case you have trouble with the scientific language, here's the summary:

1: you cannot win 2: you cannot break even 3: you cannot get out of the game

(I can't remember who originally summarized it that way, and the third law of practical thermodynamics is different from the scientific definition -- but the first two are pretty close.)

--

Tim Wescott 
Wescott Design Services 
http://www.wescottdesign.com

ondering if anyone knew how to do that. I'm really in a rush so please reso nd quickly.

nverting i'm really sorry.

So, my guess was correct that you are trying to capture RF signals from cel l towers, right? It is doable, but you would need a huge structure to capt ure enough energy to feed the power booster/inverter. You need passive str ucture (antenna) to boost to at least 700mV before any semiconductor can ac t on it. Perhaps you can build another tower to capture the signal, but yo u would have to get permission from your local building inspector with a go od reason. Building a tower to steal power from others is not a good reaso n.

Getting free power/money is not easy. Otherwise, we would not be hanging a round here wasting time.

Not a problem. None of us came into the world knowing everything.

Dan

No problem. 10 mV by itself is a meaningless number in terms of power. For power you need to know both the voltage and current. So tell us how much current you can provide at 10mV and we/you know the power. (if you don't know the current you may know the source impedance/ resistance.) Thermocouples have low source impedance.

George H.

wondering if anyone knew how to do that. I'm really in a rush so please re sond quickly.

converting i'm really sorry.

ell towers, right? It is doable, but you would need a huge structure to ca pture enough energy to feed the power booster/inverter. You need passive s tructure (antenna) to boost to at least 700mV before any semiconductor can act on it.

Not true, or at least untrue if you can work out a synchronous rectificatio n scheme based on MOSFET switches, which has been done.

have to get permission from your local building inspector with a good reaso n. Building a tower to steal power from others is not a good reason.

around here wasting time.

Agreed.

--
Bill Sloman, Sydney

Well at least you stated the objective. I'm not going to be smarmy, but you really can't do what you want. Power is conserved. So if you think you can boot the voltage, the current will drop accordingly. And pulling a signal out of the aether, I suspect you don't have much power to start with.

On a sunny day (Tue, 18 Feb 2014 16:08:44 -0800 (PST)) it happened snipped-for-privacy@gmail.com wrote in :

That is not correct, I have done a thermocouple powered converter using JFETs driving a LED.

You need a LOT of current, so as others mentioned. power is always conserved. If not ...

No way will you grab it from the air unless straight in the beam of the transmitter. Best bet is use solar, it is available some parts of the day in some places:

The effective capture area for a simple dipole is about 0.12 square wavelengths, thus the power drops to 1/4 if the frequency is doubled, thus you would need 4 dipoles to get the same power at double frequency.

In a direct line of sight situation, calculate the power density at your site (using the inverse square law) and multiple it with the effective capture area of the dipole(s) and you will know how much power will be available.

Use a transformer to step up the voltage.

For narrow band operation, just use an LC resonator circuit with the low impedance (50-300 ohm) antenna connected across a tap at the lower end of the inductor and get the high voltage, high impedance across the capacitor.

For UHF+ frequencies, you could use a 1/4 wave resonator, connect the antenna by a magnetic link at the low end of the resonator and a capacitive high impedance coupling near the top of the resonator.

If you happen to live very close to a medium wave (AM) transmitter, you might be able to capture quite a lot of power, which can be used to power other devices. I few decades ago, I saw a design, with a resonator+rectifier tuned to a local AM frequency feeding a freely tunable receiver with a few amplification stages.

Since the capture area for a simple dipole would be 0.12 square

a lot of power would be captured. Even a short (few meters long) monopole will have nearly as good capture area.

A electrically short antenna will have a highly reactive (capacitive) impedance and very low resistive component, so you have to tune out the capacitive reactance with some loading coils and/or pi filters to get a very low impedance resistive load, which you then can step up to high impedance high voltage levels to be rectified.

The problem is implementing the impedance match, since there are going to be lot of losses, so with an antenna system efficiency, the actual

electrically small (less than 1/10 wavelength) magnetic loops.

This impedance issue is of course the same, as the problem of feeding a small 1-3 m car mounted MF/HF transmitter antenna, so take a look at those systems and it may also help gathering power with electrically very short antennas.

On a sunny day (Wed, 19 Feb 2014 08:02:20 +0200) it happened snipped-for-privacy@downunder.com wrote in :

Long ago, in my school days, I build some high power linears, and had a long antenna in the garden, for the SW amateur bands.

You could walk around the garden with a neon bulb and it would light up. Something like 500 W, I used a 250 W or something light bulb for testing as dummy load, all tubes of course, 1 kV supply, big capacitors.

Cellphone towers are in the hundreds of MHz range I think, several frequencies. At those frequencies you could perhaps use a dish... Focusing always helps. Radio telescope size, but really a solar cell is much easier. In the past there were treads here about tapping the energy from power lines, one guy has a bunch of fluorescent tubes stuck in the ground with one end, lighting up under a HV power line.

And then there is wind power, even a small electric permanent motor with a fan on it will give you more power than all that other stuff.

Typically in 0.4-2.5 GHz range,

A cell site might radiate about 100 W total.

A dish is broadband, so you just need a broadband feed, which is much

would produce about 100 mW, 1 mW and 10 uW for 10, 100 and 1000 m distance respectively.

Stepping up a broad spectrum is harder compared to a single frequency band at those frequencies (ordinary transformers will not work).

That might be the rated combined transmitter power. However cell phones (and broadband) use some form of adaptive power control to extend hand set battery life and help reuse frequencies between different cell phone sites. All transmitters might not be in use all the time. Directional antenna panels and electronic beam steering (MIMO) might change the power levels in different directions.

That would be the power levels with all transmitters at nominal power into omnidirectional antennas, so in order to get some average or worst case values divide those power levels by 10 or 100 respectively.

On a sunny day (Wed, 19 Feb 2014 10:40:45 +0200) it happened snipped-for-privacy@downunder.com wrote in :

Yes, you proabbly get more power from somebody else using a cellphone next to you :-) In the tube it certainly interfered with my old walkman.

I'm sorry, but did I walk into a lunatic asylum for EE's?

And a few lunatic philosophers. Welcome aboard. ;)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

We've been expecting you.

--sp

You made it just in time. We are all leaving for the mother ship tomorrow.