RF galvanic isolator ...

Careful. Two things:

a. A sprawled out coax transformer can radiate like heck. Not good during EMC cert.

b. There needs to be something in writing from the manufacturer, about the dielectric strength. Compliance engineers usually want that paperwork or may refuse to sign off.

Of course you might have to _power_ something across that isolation gap, too.

Cheers

Phil Hobbs

Oh, that's easy. You let off a ton of press releases that you will use the super duper green-tech solar approach, then get some major loan guarantees, smile when the TV crews and the big brass from the hill is visiting. Then let the sun supply it. If it don't shine no more you just file for chapter 11 and start over :-)

Supply your own "sun" from a laser via an optical fiber to a solar cell. Return the measurement through an other fiber. Such tricks are used e.g. for phase current measurements on 400 kV (and above) HV lines.

But they won't give you a fat loan guarantee for that :-)

Anyhow, I always ferry power over magnetically. It is very cheap and you can pump tens of watts to the other side if needed. That's kind of tough to do with lasers and solar cells.

But obtaining 1MV isolation from a small POE transformer (or even your custom one) is somewhat tricky :-)

With series resonance in combination with some glass or porcelain it is feasible :-)

But you have to stick to ISM or the Federales will waltz in.

While a 10-30 cm ferrite rod with a well insulated primary at one end and a secondary at the other end can transfer a lot of power, the distance between the primary and secondary is quite small, if we have to worry about lightning strikes.

Well, the discussion started at 5kV which isn't a whole lot. Now we are already at lightning hits :-)

Many ways to get a lot of insulation. One method can be seen in things like electric toothbrushes. And those are without fancy magnetics, it's all rather simple in there and every penny in production counts. If you really engineer things out well, keep it resonant and all that, you can transfer a lot of power through several centimeters of glass, porcelain or other insulation materials.

Think about it this way: There has to be some way those 380kV are transformed down to more manageable local voltage levels, you can buy transformers for that off the shelf. Ok, big shelves. They are expected to work at 50Hz or 60Hz and at very good efficiency, soemthing we don't have to be concerned about when transferring a few watts or tens of watts.

Sometimes I wish there was an ISM frequency in the 2-3MHz range, or maybe even one just below the AM band. It would make life so much easier in that field.

Just for fun, pull the timing information from the cell phone network (or GPS) and phase lock all your disparate local oscillators to that. Yeah, a totally impractical idea, but nearly implementable.

I'm

a big

need

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er

uh huh, why in the earth we have to spend tons of joules just to have information such as time reference moving from one place to another ?

:-))) it remind my phone bill still in the in the inbox

halong schrieb:

Hello,

I would send it over an optical fiber. If 200 MHz is to fast for a cheap modulator, the frequency is easily converted to 6.25 MHz with a binary divider 1:32. If you need the 200 MHz on the other side, a PLL could transform back to the 200 MHz. But to measure the 200 MHz clock, the

Bye

That's almost like a client had it until I came in :-)

Fiber-optics stuff is very expensive, much of it due to labor. Someone has to assemble the connectors onto the fiber, polish the front and all that. Or you have to buy a fiber link, curl it up and strap it down. But that'll be expensive as well. A custom transformer is much cheaper. Once production training has occurred those can be assembled in minutes.