Aces High Bulletin Board
General Forums => The O' Club => Topic started by: MK-84 on January 02, 2012, 02:37:59 AM
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Total long shot here...
I want to build/or acquire this something that creates a 147.7 kHz square wave AC signal.
This does it. http://www.sparkfun.com/products/9002
But I want something that is NOT variable as that product is.
Power supplied must come from a standard US wall outlet and, looking at the specs I assume on using a 12vdc transformer.
Any ideas on the parts needed, and/or how to do the math?
Without getting into boring detail the project involves magnetic resonant coupling, and I'm hoping we have some experts here.
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(http://img9.imageshack.us/img9/5355/ss1wtl.jpg)
your welcome
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just calibrate it to the required frequency and then leave it alone.
you could always use trim pots instead of the shafted ones if youre worried about them accidentally moving.
Ive been looking for a similar board which goes up to the 10 MHz range for testing network cabling, not having much luck tho :(
edit: finally found one (http://kitsrus.com/pdf/k101.pdf (http://kitsrus.com/pdf/k101.pdf)), $110 seems a bit steep tho.
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What are you making? A Flux Capacitor?
Or Space Modulator perhaps
Actually, I would check GE, sounds like something they would have tech info on.
They, of course do a lot of Magnetic Resonance stuff.
:cheers: Oz
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What output voltage are you needing?
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What output voltage are you needing?
The project is specifically to charge camera's and wireless devices (cell phones) over the air. The voltage I need is nominal at 5.4vdc, but it can in theory go as low as 3.7vdc.
I am trying to build an inductive coil specific to this application.
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So your building a tesla coil in a way?
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No. Similar in that there is wireless transfer of energy, but no.
Inductive charging uses magnetisim to transfer energy, heres a link
http://www.engadget.com/2009/05/12/d-i-y-wireless-power-project-unleashes-your-inner-mad-scientist/
This isnt exactly what I want to do, and I need something smaller, this can be achieved but, I am unsure of how what equation to use to find what I need, so that I can get the output I need and it not be adjustable.
I'm asking here because I'm hoping someone is an expert in electronics.
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The project is specifically to charge camera's and wireless devices (cell phones) over the air. The voltage I need is nominal at 5.4vdc, but it can in theory go as low as 3.7vdc.
I am trying to build an inductive coil specific to this application.
When you say over the air, do you mean at some distance or are you willing to have it be up close? The reason I ask is that I've seen a number of people modify Palms Touchstones chargers for use with other devices. You can even pick them up pretty cheap now that HP has effectively killed Palm off.
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so that I can get the output I need and it not be adjustable.
I answered that already.
Why a square wave and not a sine btw? :headscratch:
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I always wondered how efficient inductive charging is. I know the technology works and is getting increasingly popular but how much electricity is wasted in the process?
I just can't wrap my head around how inductive technology could provide any more than a small 'trickle charge' which might be good enough to charge a cell phone but now I hear people talking about inductive charging pads for electric cars! It just seems to me that something like that would take weeks to charge up something like that!
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induction is actually pretty dern good. It's used for charging but it's also used in anything with a transformer. From the little one in your power supply to the big ones on your ower lines.
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The device to be charged and the charger would have to be within a foot of each other for this to work.
Remember.....we're charging here.
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The device to be charged and the charger would have to be within a foot of each other for this to work.
Remember.....we're charging here.
Distance is a pretty big issue. A foot would require one heck of an EM field not to mention the alignment issues.
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Just dismantle a toothbrush they commonly load by inductive loops :)
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That is beyond cool and very creative, but if it can charge phones wirelessly won't it cause interference?
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That is beyond cool and very creative, but if it can charge phones wirelessly won't it cause interference?
nope! I have wireless chargers for my phone and I've never noticed any degradation of signal.
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nope! I have wireless chargers for my phone and I've never noticed any degradation of signal.
Thats something I want to try!
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It may interfere with other services depending on what frequencies are used. Problems with FCC maybe.
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I answered that already.
Why a square wave and not a sine btw? :headscratch:
Sorry did not understand your post. (little uh...I like beer, leave it there :)
I requested a square wave because that was listed in the link I provided. I am not opposed to a sine wave at all.
But I would thank that to build an inductive coil using a square wave would be easier (for me anyways) since we're dealing with pulses of voltage, which is more defined then an analog component?
I used to manage a RadioShack (for a very long time), if you need a cell phone I can take care of you, but this is way beyond my knowledge. I would guess I have a 101 level college equivalent in electronics if that helps)
To address other questions:
No, interference will likely not be a problem. We're using a magnetic field to create power. (your flip cellphone probably has a magnet to tell when it's closed or open)
Off subject, Radio can, as can your wireless internet, among a lot of other things. It's an issue of frequency, my blackberry causes my wireless mouse not to function if it's too close for example)
Range to what I want only needs to be measured in inches. Anything more and this becomes extremely expensive, and inefficient. (for my project anyways)
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The device to be charged and the charger would have to be within a foot of each other for this to work.
Remember.....we're charging here.
I'm looking at inches. efficiency drops off very quickly
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just calibrate it to the required frequency and then leave it alone.
you could always use trim pots instead of the shafted ones if youre worried about them accidentally moving.
Ive been looking for a similar board which goes up to the 10 MHz range for testing network cabling, not having much luck tho :(
edit: finally found one (http://kitsrus.com/pdf/k101.pdf (http://kitsrus.com/pdf/k101.pdf)), $110 seems a bit steep tho.
No it turns out I was not drunk (well, sorta I was)
But...The website you gave used the part that I want to replace. But! we're on the same page now!
I want it to be NON-adjustable, not really for cost (although thats nice) but for size. And I do not need it to be adjustable. I Do need a wireless output voltage between 3.7 and 5.3 and a amperage at 350ma to 750ma.
The numbers are varied because they will all work to some degree, but maybe this helps someone?
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I think your best bet would be to look at an existing object.
http://www.amazon.com/gp/aw/d/B003O76EE2/ref=mp_s_a_4?qid=1325768704&sr=8-4 (http://www.amazon.com/gp/aw/d/B003O76EE2/ref=mp_s_a_4?qid=1325768704&sr=8-4)
$13 and it's all there. You could easily modify it for your needs. I use them for my phone and am able to charge up to 500 mV. Like I mentioned before, I've seen them modified for other devices.
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OK, the non adjustable part is easy. Assuming this kit (in your link) is what you want, simply build it and calibrate it, then measure the resistance of each potentiometer ,at its setting point, from the wiper to one side and then the other side and buy, makeup a resistor(s) to replace the pots. Other wise you could build(design) an oscillator circuit from an op-amp IC. Ratshack (sorry) used to sell books by(run Forrest run) Mimms I think his name was with lots of osc. circuits. etc.
There are prolly a hundred single chip special purpose oscillators on the market. You could do a search for oscillator IC's and see what comes up.
BTW a function generator has not only variable frequency, but variable pulse width and amplitude.
A note once you get the freq, rise time. pulse width you want, you will then need to add an amplifier at the output to get the current handling capabilities you want.
What are you charging or did you answer that already?
anyway good luck and feel free to PM if you like as I don't visit these threads all that often but I log in a couple time a week to check the squad forum.
:cheers:
Jenks