The biggest difference is that a microwave oven can easily be 1500W while a cellphone is 0.5W or less. I'm not aware of any fundamental differences.

The voltage / current argument is something else entirely. It's one of those things that's technically accurate but practically dubious. Just voltage (as in you're in an electric field) doesn't necessarily harm you (just V, no I hence no P) while having a current flowing through you does hurt you (there's I so there must be V hence P). The problem is that a high voltage is more likely to cause a significant current (like Ohm's law) so without exactly knowing the current capabilities of the voltage you need to assume it's dangerous.
Tasers and the like generate thousands of volts with very high internal impedance, limiting the current to low values. It's supposedly safe but people do die from them occasionally.

 

The reason there is a cell phone tower about every 3sq miles is because of the low power transmitters in the phones. Back in the day of the BRICKs:

They had MUCH more powerful transmitters. There were sometimes only two or three towers per city opposed to hundreds now.

The dynatac 8000 had a transmitter power of 20w and you couldnt touch it when rapid 1hr charging. The battery got to 120F+ So you were stuck with 30 to 60 minutes of talk time then 10 hours of recharge.

http://www.americanheritage.com/articles/magazine/it/2007/3/2007_3_20.shtml

 

Hehe nice pic

 

but I also heard that increasing the voltage and leaving current very minimal will not kill you because current is what does the damage,

And you would be perfectly correct if you were talking about direct DC current. This has NOTHING to do with direct conduction, we're at 2.4ghz in the RF spectrum in free space! Go more than a few hundred mhz above or bellow that sweet spot and it's not gonna heat in the same manner.

You can NOT only look at current and not power. While a super low current at a very high voltage will not disrupt a human electrical system, the sheer Ohmic heating from a very high voltage source and very low current won't stop your heart, it'll just bake you like last nights potato.

 

it'll just bake you like last nights potato.

Actually, I had enchiladas. baked.

Plain and simple. When the numbers get that high, the human body should not be involved unless the brain that is in that body is VERY well versed in the control, properties and safety factors required for such high numbered whatnots.

 

we're at 2.4ghz in the RF spectrum in free space! Go more than a few hundred mhz above or bellow that sweet spot and it's not gonna heat in the same manner.

Actually 2.4 GHz was chosen precisely because it is not a sweet spot. If microwave ovens operated at the resonant frequency of water, which by the way is 22.235 GHz, most of the energy would be absorbed at the surface of the food which would over cook and much less would reach the center of the food so it would be undercooked. By choosing a frequency at which the energy is only partially absorbed, there is still enough to heat the centers of foods and at a rate that they don't overcook too rapidly.

I used to work with and engineer who built a device to cook wieners by putting them one at a time inside a coil at about 450 MHz.

 

That's pretty cool. I heard 2.4 GHz has special properties like exciting water molecules and all. So technically we're being slow cooked by all these wi-fi routers everywhere hehe

 

I may have been a little presumptuous with my declaration of a sweet spot, but I didn't mean the whole water hole thing, that was debunked ages ago, though it still tends to be commonly thought of.

I'd be curious to know what he used that generated that much power at 450mhz, induction heater?

 

He was an RF engineer like me and I suppose he just made a high power oscillator for it. I don't remember him ever mentioning how much power it put out. He said he wrapped the coil around a pickle relish bottle which was long and narrow and just a little larger than the wiener. As the wiener cooked, it swelled sealing the opening of the bottle and causing pressure to build up inside the bottle. At about the point when the wiener was fully cooked the pressure had increased to the point that it shot the wiener out of the bottle.

The article about the DynaTAC 8000 brought back memories. I started at Motorola in 1983, just before the DynaTAC 8000 came out, only I worked in the division that designed the base station transmitters. They gave us all carphones, mounted in the trunk with the headset in the front to test for problems like switching between sectors.

By the way the 8000's successor, the first flipphone, had some interesting technology. When it was built it got too hot. To get rid of the heat they used a solid copper circuit board and silk-screened a solder resist layer over the copper leaving holes where they wanted grounds. Next they silk-screened the traces on top of the solder resist layer and passed the traces over the holes in the solder resist wherever they wanted to ground them. They kept alternating solder resist and traces until the circuit was complete. Last the parts were glued in place and wave soldered.