<div dir="ltr">That would be a mains frequency square wave, which is full of harmonics.<div>Any idea what the carrier frequency of the wireless charger is ?</div><div>Energy transmission freq ?) (Or is it just one freq ?)</div><div>Is it inductive coupling charger to device-being-charged ?</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Jun 24, 2018 at 12:22 PM, Jerry Durand via Stagecraft <span dir="ltr"><<a href="mailto:stagecraft@theatrical.net" target="_blank">stagecraft@theatrical.net</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<font face="Arial">The charger is two wire double insulated, but note
it's a wireless one. It charges the device when it's just close
to it.<br>
<br>
The inverter output isn't floating, but I'm pretty sure the way it
generates a pure sine wave is the key. In making a pure sine wave
the first thought that would come to mind is tying the neutral to
ground in the inverter and then just making a sine on the "hot",
but that requires it to have twice the internal DC voltage to go
from positive peak to negative peak.<br>
<br>
So what this does is the "neutral" output is a pure square wave
while the "hot" output is two half sine waves. When the "neutral"
is at ground, the "hot" makes a half wave from ground up to peak,
then back to ground. When it gets back to ground, the "neutral"
and "hot" are switched together to peak voltage, then the "hot"
makes an inverted wave starting from the peak voltage, going down
to ground at what would be the - peak, then back up to peak
voltage. Both lines are then switched together back to ground to
start everything over again.<br>
<br>
From the point of view of any modern device (pretty much
everything is agnostic about which wire is "neutral" and which is
"hot") this works great.<br>
<br>
But, back to the wireless charger, this would be putting a mains
frequency (50/60Hz) bias into the air-coupled signal to the device
to be charged. I suspect this either prevents the charger from
detecting the presence of a device to be charged or the device to
be charged from realizing it's within range of the charger.<br>
<br>
Remember when battery chargers were a transformer, a full wave
rectifier if you were lucky, otherwise a single selenium
rectifier, and that was about it?<br>
</font><div><div class="h5"><br>
<div class="m_-8361971607410898584moz-cite-prefix">On 06/24/2018 04:47 AM, Dan Sheehan via
Stagecraft wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">1) Is perhaps the charger miswired so it uses
hot-to-ground instead of hot-to-neutral ?
<div> You could check for this by making an adaptor with
neutral opened.</div>
<div> If the charger works on this, it's wrong.</div>
<div><br>
</div>
<div>2) Inverter output is just floating ? </div>
<div> That's perhaps a no-no, unless it's *specified* to be a
ground isolator.</div>
<div> Should be OK, and desirable, to tie the inverter output
neutral to ground.</div>
<div><br>
</div>
<div>3) I've seen flourescent light fixtures (the 4-foot-long
tube "shop light" kind)</div>
<div> not start if the metal case is not grounded, or in at
least one case,</div>
<div> not start if the sheet metal cover is not present; </div>
<div> touch the glass with your hand, and it lights up then
runs find.</div>
<div> Apparently it requires capacitive coupling from the tube
to ground to start.</div>
<div> </div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Sun, Jun 24, 2018 at 1:48 AM, Me via
Stagecraft <span dir="ltr"><<a href="mailto:stagecraft@theatrical.net" target="_blank">stagecraft@theatrical.net</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I just had
a wireless charger refuse to work on a pure sine wave
inverter. I tried it on a wall outlet, works fine. Tried
again on the inverter, no work.<br>
<br>
I checked the inverter output with a 'scope in differential
mode, looked close to perfect. So...???<br>
<br>
Finally figured out the inverter isn't referenced to ground
like the mains are. Nothing cares except this one charger.
Must be a marginal design in the charger and the lack of a
ground reference kills the function.<br>
<br>
Every day is a surprise!<span class="m_-8361971607410898584HOEnZb"><font color="#888888"><br>
<br>
-- <br>
Jerry Durand, Durand Interstellar, Inc.<br>
<a href="http://www.DurandInterstellar.com" rel="noreferrer" target="_blank">www.DurandInterstellar.com</a><br>
tel: +1 408 356-3886<br>
@DurandInterstel<br>
<br>
______________________________<wbr>______________________________<br>
For list information see <<a href="http://stagecraft.theprices.net/" rel="noreferrer" target="_blank">http://stagecraft.theprices.n<wbr>et/</a>><br>
Stagecraft mailing list<br>
<a href="mailto:Stagecraft@theatrical.net" target="_blank">Stagecraft@theatrical.net</a><br>
<a href="http://theatrical.net/mailman/listinfo/stagecraft_theatrical.net" rel="noreferrer" target="_blank">http://theatrical.net/mailman/<wbr>listinfo/stagecraft_theatrical<wbr>.net</a><br>
</font></span></blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
-- <br>
<div class="m_-8361971607410898584gmail_signature" data-smartmail="gmail_signature">
<div dir="ltr">
<div>
<div dir="ltr">
<div>
<div dir="ltr">
<div>...Dan Sheehan<br>
Fixer of things that break</div>
<div>TD Walpole (MA) Footlighters<br>
<br>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
<br>
<fieldset class="m_-8361971607410898584mimeAttachmentHeader"></fieldset>
<br>
<pre>______________________________<wbr>______________________________
For list information see <a class="m_-8361971607410898584moz-txt-link-rfc2396E" href="http://stagecraft.theprices.net/" target="_blank"><http://stagecraft.theprices.<wbr>net/></a>
Stagecraft mailing list
<a class="m_-8361971607410898584moz-txt-link-abbreviated" href="mailto:Stagecraft@theatrical.net" target="_blank">Stagecraft@theatrical.net</a>
<a class="m_-8361971607410898584moz-txt-link-freetext" href="http://theatrical.net/mailman/listinfo/stagecraft_theatrical.net" target="_blank">http://theatrical.net/mailman/<wbr>listinfo/stagecraft_<wbr>theatrical.net</a>
</pre>
</blockquote>
<br>
<pre class="m_-8361971607410898584moz-signature" cols="72">--
Jerry Durand, Durand Interstellar, Inc.
<a class="m_-8361971607410898584moz-txt-link-abbreviated" href="http://www.DurandInterstellar.com" target="_blank">www.DurandInterstellar.com</a>
tel: +1 408 356-3886
@DurandInterstel
</pre>
</div></div></div>
<br>______________________________<wbr>______________________________<br>
For list information see <<a href="http://stagecraft.theprices.net/" rel="noreferrer" target="_blank">http://stagecraft.theprices.<wbr>net/</a>><br>
Stagecraft mailing list<br>
<a href="mailto:Stagecraft@theatrical.net">Stagecraft@theatrical.net</a><br>
<a href="http://theatrical.net/mailman/listinfo/stagecraft_theatrical.net" rel="noreferrer" target="_blank">http://theatrical.net/mailman/<wbr>listinfo/stagecraft_<wbr>theatrical.net</a><br>
<br></blockquote></div><br><br clear="all"><div><br></div>-- <br><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div>...Dan Sheehan<br>Fixer of things that break</div><div>TD Walpole (MA) Footlighters<br><br></div></div></div></div></div></div></div>
</div>