Help with electronics!

[MK-84]

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.

[helbent]

your welcome

[RTHolmes]

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), $110 seems a bit steep tho.

[ozrocker]

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.
                                                                                                                                                         Oz

[zippo]

What output voltage are you needing?

[MK-84]

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.

[F22RaptorDude]

So your building a tesla coil in a way?

[MK-84]

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.

[clerick]

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.

[RTHolmes]

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? 

[Tigger29]

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!

[clerick]

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.

[icepac]

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.

[clerick]

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.

[MrRiplEy[H]]

Just dismantle a toothbrush they commonly load by inductive loops