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3.5V x 35 lights in series = 122V so that part looks right.
1. How does the resistance of the new bulbs compare to the original
(working) bulbs?
2. Might be worthwhile to feed 3.5V from a bench power supply across a
fresh bulb to see if it burns out just as quickly as when plugged into
the string. You could also use batteries but it might be trickier to
hit 3.5V. Three NiMH batteries in series would yield 3.6V which ought
to be close enough but you have to be careful not to use them straight
off the charger since initially they'll be at 1.4V per cell.
3. You said you didn't notice the new bulbs overly bright before they
burn out. I wonder if they're really burned out or if the shunt at the
bottom of the bulbs are for some reason causing a premature short
circuit? Using a magnifying glass, can you tell if the filaments are
really separated?
J
On 11/27/22 17:36, Karl Vacek wrote:
> Shop content - as soon as I get the Christmas tree done I can go back
> to the shop and work on something.
>
> We have many strings of Christmas lights on the tree. Almost all are
> 30 year old plus Silvestri 35-light series strings. Silvestri calls
> for 3.5 volt replacement bulbs. Replacement bulbs were getting scarce
> locally so I ordered some from an Amazon seller, and some from a place
> that specializes in hard to find items. They're of two brands, all
> 3.5 volt for 35-light sets. Every one I install lights for a second
> and burns out immediately. They don't look overly bright as if they
> were for a lower voltage. Once burned out the string still stays lit
> because they have the same jumper as the originals.
>
> What am I missing?
>
> Thanks !
> Karl
>
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<div class="moz-cite-prefix">3.5V x 35 lights in series = 122V so
that part looks right.</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">1. How does the resistance of the new
bulbs compare to the original (working) bulbs?<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">2. Might be worthwhile to feed 3.5V
from a bench power supply across a fresh bulb to see if it burns
out just as quickly as when plugged into the string. You could
also use batteries but it might be trickier to hit 3.5V. Three
NiMH batteries in series would yield 3.6V which ought to be close
enough but you have to be careful not to use them straight off the
charger since initially they'll be at 1.4V per cell.<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">3. You said you didn't notice the new
bulbs overly bright before they burn out. I wonder if they're
really burned out or if the shunt at the bottom of the bulbs are
for some reason causing a premature short circuit? Using a
magnifying glass, can you tell if the filaments are really
separated?<br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">J</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix"><br>
</div>
<div class="moz-cite-prefix">On 11/27/22 17:36, Karl Vacek wrote:<br>
</div>
<blockquote type="cite"
cite="mid:184bb3c67e8.2806.cd27845553c78383775132770b7455be@gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="auto">
Shop content - as soon as I get the Christmas tree done I can go
back to the shop and work on something.
<div dir="auto"><br>
</div>
<div dir="auto">We have many strings of Christmas lights on the
tree. <span style="font-size: 12pt;">Almost all are 30 year
old plus Silvestri 35-light series strings. Silvestri calls
for 3.5 volt replacement bulbs. Replacement bulbs were
getting scarce locally so I ordered some from an Amazon
seller, and some from a place that specializes in hard to
find items. They're of two brands, all 3.5 volt for
35-light sets. Every one I install lights for a second and
burns out immediately. They don't look overly bright as if
they were for a lower voltage. Once burned out the string
still stays lit because they have the same jumper as the
originals.</span></div>
<div dir="auto"><br>
</div>
<div dir="auto">What am I missing?</div>
<div dir="auto"><br>
</div>
<div dir="auto">Thanks !</div>
<div dir="auto">Karl</div>
</div>
<br>
</blockquote>
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