wireless 'power' transfer? / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

wireless 'power' transfer?

1 2 3 next

Move Thread

LAN_403

Marko

Mon Mar 06 2006, 08:35PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Here is a movie

So tesla maybe wasnt (completly) crazy.
TCs and probably magnifiers even better can be used to transmit usable amounts of power over distances.
I did some half-baked experiment with miniatures, and got interesting results.
'transmitter' was small 2Mhz SSTC, driven at 36V with royer circuit.
I used another small secondary as a 'receiver', but it was actually not in resonance with coil so its actually wonder that it actually works.
Placed that secondary with neon bulb near 1m away from coil, and both are ! ungrounded.
I supressed the breakout at coil to minimize losses (even tesla didnt like sparks, for same purpose)
When turned on it did nothing, coil just heated up fast. I moved my hand close to its sphere, and magic happened.
Neon bulb lit up 1m away from coil, that is only 7cm high and usually starts to light neon bulbs at about 7cm - same amount of power was transferred over 14 times larger distance.
Hand obivously increases Q a lot, this is more visible if I promote breakout - spark is twice bigger if grounded object is close to topload.

Later I hooked old TO-3 heatsink to my faraday cage in order to replace my hand in this dirty job.
After that I wound 8 turns of telephone wire around 'receiver' coil and it lit small 1W bulb : voltage can be stepped down to usable level.
Tried to run DC fan but I couldnt find diode fast enough to rectify ~2Mhz, some I tried just conduct capacitively and heat up.

Most interesting is that receiver doesnt like ground at all, if I approach him it 'turns off', or ground the ground wire etc.

When I grounded the coil preformance was even better but at about half a meter it suddenly drops.
Ground wire of receiver needed to be weakly coupled to ground (I placed GND wire near mains cable).

That with grounding is somewhat counter-logical (but it is not logical that non-resonant ''receiver'' even works at all) so im wondering does somebody have explanation.

In theory if TC/magnifier as one resonant circuit couples to everything around (its topload is one and earth another plate of capacitor).
If another LC in resonance is moved close enough voltage on it should rise to the voltage of transmitter, and current is limited by capacitive impedance between two spheres (what is capacitance between 2 ping-pong balls 1m away - very small) but at high frequency small current can pass it, and with high enough voltage we can get considerable power in the end.

Im also interested if someone did similar experiment, seems very interesting to me

cheers...

vasil

Mon Mar 06 2006, 09:05PM

Registered Member #229 Joined: Tue Feb 21 2006, 07:33PM
Location: Romania
Posts: 506

I really like your experiment, very well done.
Describe it in detail and put it on a site page. It is worthing to bookmark it.

vasil

Hazmatt_(The Underdog)

Tue Mar 07 2006, 12:04AM

Registered Member #135 Joined: Sat Feb 11 2006, 12:06AM
Location: Anywhere is fine
Posts: 1735

In a way I was playing with similar things, except my coils were not matched at all.

In my case I put another secondary, possibly 90% match without topload on the secondary ground plane of the resonant secondary being driven in the TC. I only really did this to check my tuneing. With the best tune, the arcs from this separate secondary has the longest arcs. Now, of couse, in this case it can only output about 4" arcs, but I figure that's pretty good for only being inside the RF field, and not being driven at all by any circuit.

I would play more with it and see if I could get ~3' arcs from a seperate coil, but I really doubt it. I think it would be halved.
On the other hand, you could ask someone with a large 'twin' system and see what they have to say.

HV Enthusiast

Tue Mar 07 2006, 12:25AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

This is how Tesla ran his remote controlled boat - sampe princicples using an array of coils to transfer power to control different portions of the boat.

Marko

Tue Mar 07 2006, 08:56AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hazzmat, you got sparks from your 'receiver' secondary

How close was it, if you can draw 3 inch sparks its a lot of power in there.
You could power car halogen bulb with no problems, but you didnt state the distance between coils?

Also if TC has breakout point and throws streamers and sparks they must be supressed - huge power loss. You may need to stabilize your coil's Q then if you dont have good ground conductivity (mine was wooden table and some walls, bad) so adding ground armour to one side of sphere helped a lot (coil even produced bigger sparks then)

..And you say your 'resonator' needed good grounding?

For my coil it cannot be operated long as secondary heats up in seconds.
Without breakout in minute its so hot that its PVC former tends to melt and deform, so overlapped windings started to appear.
0,1mm wire is obivously far too thin for 2Mhz, skin depth is ridiculuosly small and coil loses too much power there.
Secondary used for resonator is filled with poliester so in SSTC duty it surely won't melt...
Without breakout point coil can draw 10W from 36V supply (about 300mA rms) and most of power is turned to heat.

ragnar

Tue Mar 07 2006, 10:23AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

I've had 7cm/just-less-than-3-inch sparks from a separate resonator.

Positioned about 50cm away, left the ends dangling near each other, and fiddled the frequency of the coil to drive it out of resonance... The sparks were very weak of course, not to mention my diodes got stinking hot and I blew a few MOSFETs up.

Firkragg, I think you'll get more valuable (as in you can graph different values and write down what happens under different conditions and note trends, patterns and relationships) results if you make a variable-frequency coil with some ultrafast diodes on your FETs. Although only a novelty (and done before many many times), playing around with the coupling between two totally separate coils can be a lot of fun.

Try disconnecting the ground of your first/'transmitting' coil, too, then see whether you can get the same results

Marko

Tue Mar 07 2006, 10:53AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Try disconnecting the ground of your first/'transmitting' coil, too, then see whether you can get the same results

Ground IS disconnected, I grounded only cage that I used to obtain better capacitive coupling to sphere and gain more Q (again proves TC as resonant transformer) so it helps wireless transfer a lot.

Receiver doesnt like to be grounded, maybe it must be 100% resonant or it just increases impedance too much.

I've had 7cm/just-less-than-3-inch sparks from a separate resonator.

Positioned about 50cm away, left the ends dangling near each other, and fiddled the frequency of the coil to drive it out of resonance... The sparks were very weak of course, not to mention my diodes got stinking hot and I blew a few MOSFETs up.

Size of coils, input power, pics, movies, anything

Steve Conner

Tue Mar 07 2006, 11:57AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I managed to get similar results to blackplasma's once while trying to get my DRSSTC to run as a twin coil. I made another secondary and topload that resonated at about the same frequency and put it 3ft away. I grounded the base of the other secondary too, so it was being driven only by capacitive coupling between the two toploads.

By playing with the tuning controls, I found that there were now three resonant frequencies. Depending on which frequency I used, the sparks would come from one coil, or the other, or both at once. When both coils were sparking at once, the streamers from the two coils looked about the same size and strength. Each bunch of streamers was about 2ft long but they refused to connect into a 3ft arc. I guessed that was because they were 90' out of phase.

ragnar

Tue Mar 07 2006, 11:57AM

Registered Member #63 Joined: Thu Feb 09 2006, 06:18AM
Location:
Posts: 1425

Sorry, to me it didn't merit a photograph - power input was 80V at maybe 0.5A... 40W. The diodes were a great deal hotter than I'd like, too.

The secondary was as many turns of 0.15mm as would fit on 15cm of 5cm pipe, the 'receiver' as you'd like to call it, as many turns of 0.15mm as would fit on a 25cm pipe of the same diameter.

The sparks were flimsy like a badly tuned SGTC arcing to ground. Similar results with secondary coil grounded and receiver coil grounded - the performance was proportional to frequency and distance... hehe, felt like 1/d^99 or something as it was difficult to get any results further away than 50cm,

[oops, Steve just beat me to it]
As Steve has demonstrated, twiddling the frequency would shift breakout from one coil to both to the other. For my fiddling, I generally tweaked it for zero breakout (and maximum diode heatage) on my secondary or max breakout on the receiver.

Marko

Tue Mar 07 2006, 01:13PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

I think that 'breakout - shifting' can be explained.

And coils are not in different, but in exactly same phase all the time, there is no potential difference and thats why streamers didnt connect in arc, they are actually more like single streamer, split.

Coils most probably had very close Fres but it couldnt be similar, so shifting oscillator frequency gave more power to first or second coil depending on their frequencies.

Obivously coils must be really completly resonant for good preformance

I get maybe 1cm spark when I put the resonator 6-7cm to coil (distance when it lights neon bulbs) and at half a meter, a meter I get maybe few hundred volts but still enough power to light 1W bulb and neon. I still cant find diode to rectify output and run small motors, etc...

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob