From: David Van Horn <david.vanhorn@backcountryaccess.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
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Date: Tue, 4 Feb 2020 14:24:06 -0800
Subject: RE: [EE] Power transmission
Thread-Topic: [EE] Power transmission
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Class E drive?

--
David VanHorn
Lead Hardware Engineer

Backcountry Access, Inc.
2820 Wilderness Pl, Unit H
Boulder, CO =A080301 USA
phone:=A0303-417-1345 =A0x110
email:=A0david.vanhorn@backcountryaccess.com=A0

-----Original Message-----
From: piclist-bounces@mit.edu <piclist-bounces@mit.edu> On Behalf Of Harold=
 Hallikainen
Sent: Tuesday, February 4, 2020 2:15 PM
To: Microcontroller discussion list - Public. <piclist@mit.edu>
Subject: Re: [EE] Power transmission

True. However, this would reduce efficiency since the FET drain would see a=
 sine wave. An interesting approach I've seen in broadcast transmitters is =
class F amplifiers where harmonic filters are added between the transistor =
and the output. This is shown, for example, at
https://etd.ohiolink.edu/!etd.send_file?accession=3Dwright1422547511&dispos=
ition=3Dinline#page=3D15
.. This allows the transistor to have a square wave (drain voltage zero when=
 current high, drain current zero when drain voltage high) while the output=
 is a sine wave.

Harold


> A high q resonant circuit should help
>
> On Tue, Feb 4, 2020, 12:32 PM Harold Hallikainen=20
> <harold@mai.hallikainen.org>
> wrote:
>
>> I wonder about radio interference with several watts of 250 kHz=20
>> square wave. One nice thing about the Linear Technology designs (at=20
>> Analog
>> Devices) is that they comply with EMC requirements.
>>
>> Harold
>>
>> > If you want to set up something simple for a test you need a mosfet=20
>> > driver, a coil of 20awg or so wire, about 30 turns in a coil about=20
>> > 3 inches across, a coil with about 200uh , a 200pf cap and a=20
>> > schottky diode.  That is
>> the
>> > sending parts and the receiving part is a coil as close to the=20
>> > first
>> 30
>> > turn coil in size and shape.  I can post more details if interested .
>> This
>> > will transfer about 3 watts using a frequency of 250khz  over a
>> distance
>> > of
>> > about 1 inch.   Of course you also need a frequency generator with
>> square
>> > wave output.    The most important part is the coils, the better the q
>> the
>> > more efficient it will be.
>> >
>> >
>> > On Mon, Feb 3, 2020, 5:44 PM Neil <picdude3@narwani.org> wrote:
>> >
>> >> I'm tinkering with power transmission for getting power from=20
>> >> behind a wall panel to in front.  For now I'm just experimenting=20
>> >> with the
>> idea,
>> >> but I can't find much info on the relationship between coil=20
>> >> diameter, wire diameter, number of turns, frequency, and distance.
>> >> Anyone here know anything about this?
>> >>
>> >> Cheers,
>> >> -Neil.
>> >>
>> >>
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>>
>> --
>> FCC Rules Updated Daily at http://www.hallikainen.com Not sent from=20
>> an iPhone.
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