<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body>
<p>Brilliant work George</p>
<p><br>
</p>
<p><br>
</p>
<p><br>
</p>
<div class="moz-cite-prefix">On 2022-05-09 2:07 p.m., Eileen wrote:<br>
</div>
<blockquote type="cite"
cite="mid:D5A6B985-E1EA-41EA-B0BF-007D899E61C0@gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
Good detective work.
<div><br>
</div>
<div>Eileen <br>
<br>
<div dir="ltr">Sent from my iPhone</div>
<div dir="ltr"><br>
<blockquote type="cite">On May 9, 2022, at 10:47 AM, George
Bowden <a class="moz-txt-link-rfc2396E" href="mailto:gtbowdeng@gmail.com"><gtbowdeng@gmail.com></a> wrote:<br>
<br>
</blockquote>
</div>
<blockquote type="cite">
<div dir="ltr">\ufeff
<div dir="ltr">
<div>Well, I survived. But these LED tubes need a ballast
to produce a higher voltage than 110v. The internal
capacitors limit the current way too much. Replacing
the capacitors with a single 0.1 uF capacitor, for
current limiting, allowed the dim output I desired. But
you have to get inside the bulb to do that, and the tube
is made of glass...</div>
<div><br>
</div>
<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, May 8, 2022 at
11:30 AM George Bowden <<a
href="mailto:gtbowdeng@gmail.com" target="_blank"
moz-do-not-send="true">gtbowdeng@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px
0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div dir="ltr">If anyone has some ideas on LED
and fluorescent tubes, pile in.
<div>I got some LED T8 tubes that are for direct
replacement with fluorescents connected to instant
on ballasts.
<div>I carefully looked up ballasts that are <a
href="https://www.gelighting.com/tubes-ballast-compatibility"
target="_blank" moz-do-not-send="true">compatible
to this LED tube</a> and chose to look at wiring
diagrams for a B132IUNVHE-N ballast<img
alt="image.png"
src="cid:part3.70C7ED2D.E827FF31@savinkoff.com"
class="" width="472" height="151"></div>
<div>Clearly, the two pins at each end are joined
together.</div>
<div><br>
</div>
<div>I then took apart one LED tube and drew its
schematic. The electronics are repeated at each
end of the tube (drawn one above the other), which
makes sense because tubes can be inserted in
either direction. I then drew AC power connections
per the diagram above. Pins 1 and 2 are at one end
of the tube, and pins 3 and 4 are at the other.
Given the shorting of pin1 to 2 and pin 3 to 4,
capacitors 1,2,6,&7 are shorted out, as are
resistors 1,2,3&4. Not shorted are the
capacitors and diodes next to each other.</div>
<div>Tubes also could be inserted into ballast
wiring where pin1 and pin2 are not shorted, and it
is interesting to have a tube design that must
work with 4 different power connections!!</div>
<div><br>
<div><img alt="image.png" style="margin-right:
0px;"
src="cid:part4.A8842788.BF0D7923@savinkoff.com"
class="" width="575" height="241"><br>
</div>
<div><br>
</div>
<div>Simulating this design in LTspice shows 70v
peak across the bank of leds, with
current through each bank at 3.6 milliamps.</div>
<div>There are actually 3 banks connected in
parallel of 22 leds connected in series. I've
only shown one bank.</div>
<div>I've guessed at the surface mount capacitor
values, and the simulation does not include the
loads of LED bank2 and bank 3, so it is not
quite realistic. Also, I am guessing at the LED
type.</div>
<div>Given that ballasts try to maintain a certain
current, using a 110v AC input is probably
wrong, but that is what I will use to power the
tube.</div>
<div>I might include a 1.5uF 250v cap on the input
to limit current, but the simulated current
through the LEDs is very low already...</div>
<div>My application is for a very weak light over
my keyboard, so 3.6ma might be fine.</div>
<div><br>
</div>
<div><img alt="image.png" style="margin-right:
0px;"
src="cid:part5.95457312.A333A14D@savinkoff.com"
class="" width="364" height="309"><br>
</div>
<div><br>
</div>
Now to plug it in....AAGGGHHH</div>
<div><br>
</div>
<div>-- <br>
<div dir="ltr">
<div dir="ltr">George Bowden 250-893-7423
<div>Victoria BC</div>
</div>
</div>
</div>
</div>
</div>
</blockquote>
</div>
<br clear="all">
<div><br>
</div>
-- <br>
<div dir="ltr">
<div dir="ltr">George Bowden 250-893-7423
<div>Victoria BC</div>
</div>
</div>
<span>-- </span><br>
<span>Projects mailing list</span><br>
<span><a class="moz-txt-link-abbreviated" href="mailto:Projects@vicpimakers.ca">Projects@vicpimakers.ca</a></span><br>
<span><a class="moz-txt-link-freetext" href="http://vicpimakers.ca/mailman/listinfo/projects_vicpimakers.ca">http://vicpimakers.ca/mailman/listinfo/projects_vicpimakers.ca</a></span><br>
</div>
</blockquote>
</div>
<br>
<fieldset class="mimeAttachmentHeader"></fieldset>
</blockquote>
<pre class="moz-signature" cols="72">--
Great minds discuss IDEAS.
Average minds discuss EVENTS.
Small minds discuss PEOPLE.</pre>
</body>
</html>