Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Default Relamping the shop

Â* A few months ago we had a power surge or something , blew out all the
electronic ballasts in my shop fluorescent lights . I've been limping
along ... Today I received via the USPS a box containing 10 four foot
LED tubes ... six of which are now installed in my fixtures and lighting
my shop . Simple changes to the fixtures , hot lead to one end and
neutral to the other (both pins) and bang we got light ! A lot brighter
and a different color/temperature but that I can get used to . I got the
clear tubes , upon reflection I might have gone diffused ... a piece of
scotch tape will test that . Bottom line is for under 5 bucks a tube ,
they don't cost that much more than a fluorescent tube and they'll save
me some bucks down the road in lower energy bills . And I used the
fixtures I already had .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On 9/19/2018 3:07 PM, Terry Coombs wrote:
A few months ago we had a power surge or something , blew out all

the electronic ballasts in my shop fluorescent lights . I've been
limping along ... Today I received via the USPS a box containing 10 four
foot LED tubes ... six of which are now installed in my fixtures and
lighting my shop . Simple changes to the fixtures , hot lead to one end
and neutral to the other (both pins) and bang we got light ! A lot
brighter and a different color/temperature but that I can get used to .
I got the clear tubes , upon reflection I might have gone diffused ... a
piece of scotch tape will test that . Bottom line is for under 5 bucks a
tube , they don't cost that much more than a fluorescent tube and
they'll save me some bucks down the road in lower energy bills . And I
used the fixtures I already had .



I've got 8 foot dual tube cans in my shop, and the florescent tubes work
just fine. However, my last trip over to a local store found me buying
what may well be the last case they will ever stock.

I expect I'll be forced to replace or rewire all my cans eventually
myself, but none of the places I checked had LED tubes at anywhere near
the price yours cost. Care to share your source. Also, let us know how
they do after a few years. I replaced all the bulbs in my office and
machine room with Leeson LED bulbs and the first one died within a few
months. I think I've more than half, and I only got them a couple years
ago. I originally got a lot more than I would need, and I am down to
just one or two spares.

Needless to say I'll be looking for another brand of LED bulbs next time.


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On Thursday, September 20, 2018 at 6:12:51 PM UTC-4, Bob La Londe wrote:


I've got 8 foot dual tube cans in my shop, and the florescent tubes work
just fine. However, my last trip over to a local store found me buying
what may well be the last case they will ever stock.

I expect I'll be forced to replace or rewire all my cans eventually
myself, but none of the places I checked had LED tubes at anywhere near
the price yours cost. Care to share your source. Also, let us know how
they do after a few years. I replaced all the bulbs in my office and
machine room with Leeson LED bulbs and the first one died within a few
months. I think I've more than half, and I only got them a couple years
ago. I originally got a lot more than I would need, and I am down to
just one or two spares.

Needless to say I'll be looking for another brand of LED bulbs next time.


I did a quick search on 8 foot LED tubes, and they are available from a number of sources. Did not check prices as I expect they will cost less when you need them.

Dan

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On Thu, 20 Sep 2018 15:12:50 -0700, Bob La Londe
wrote:


On 9/19/2018 3:07 PM, Terry Coombs wrote:
A few months ago we had a power surge or something , blew out all

the electronic ballasts in my shop fluorescent lights . I've been
limping along ... Today I received via the USPS a box containing 10 four
foot LED tubes ... six of which are now installed in my fixtures and
lighting my shop . Simple changes to the fixtures , hot lead to one end
and neutral to the other (both pins) and bang we got light ! A lot
brighter and a different color/temperature but that I can get used to .
I got the clear tubes , upon reflection I might have gone diffused ... a
piece of scotch tape will test that . Bottom line is for under 5 bucks a
tube , they don't cost that much more than a fluorescent tube and
they'll save me some bucks down the road in lower energy bills . And I
used the fixtures I already had .



I've got 8 foot dual tube cans in my shop, and the florescent tubes work
just fine. However, my last trip over to a local store found me buying
what may well be the last case they will ever stock.

I expect I'll be forced to replace or rewire all my cans eventually
myself, but none of the places I checked had LED tubes at anywhere near
the price yours cost. Care to share your source. Also, let us know how
they do after a few years. I replaced all the bulbs in my office and
machine room with Leeson LED bulbs and the first one died within a few
months. I think I've more than half, and I only got them a couple years
ago. I originally got a lot more than I would need, and I am down to
just one or two spares.

Needless to say I'll be looking for another brand of LED bulbs next time.


I replaced the fluorescents in my shop with a case of 20 frosted 6500K
40W 8 footers from this guy last Feb.
www.ebay.com/itm/301995907066

One half of one lamp failed within a few weeks, but that's a minor
complaint compared to the increased light, decrease in the electric
bill, and elimination of the magnetic ballast buzz.

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line. It took no more
than a couple hours to remove the magnetic ballasts and rewire the 10
fixtures.

Took a little longer to get used to the color change. Now the places
that still have the CW fluorescents look dingy to me.

We replaced the 4 foot T8's in my wife's studio about a year ago with
10 lamps from this ebay seller. No failures to date.
https://www.ebay.com/usr/minidavy?_t...72.m2749.l2754

It seem prices have stabilized or gone up a bit since my two
purchases.

--
Ned Simmons
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On 9/20/2018 6:57 PM, wrote:
On Thursday, September 20, 2018 at 6:12:51 PM UTC-4, Bob La Londe wrote:
I've got 8 foot dual tube cans in my shop, and the florescent tubes work
just fine. However, my last trip over to a local store found me buying
what may well be the last case they will ever stock.

I expect I'll be forced to replace or rewire all my cans eventually
myself, but none of the places I checked had LED tubes at anywhere near
the price yours cost. Care to share your source. Also, let us know how
they do after a few years. I replaced all the bulbs in my office and
machine room with Leeson LED bulbs and the first one died within a few
months. I think I've more than half, and I only got them a couple years
ago. I originally got a lot more than I would need, and I am down to
just one or two spares.

Needless to say I'll be looking for another brand of LED bulbs next time.

I did a quick search on 8 foot LED tubes, and they are available from a number of sources. Did not check prices as I expect they will cost less when you need them.

Dan

Â* Here's the link to where I got mine 10-100 Pack 18W 48 inch 4ft LED
Fluorescent Tube Light Bulb G13 T8 lamp fixture
https://www.ebay.com/itm/10-100-Pack-18W-48-inch-4ft-LED-Fluorescent-Tube-Light-Bulb-G13-T8-lamp-fixture/302508947434?ssPageName=STRK%3AMEBIDX%3AIT&var=601 495925403&_trksid=p2057872.m2749.l2649

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !



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On Thursday, September 20, 2018 at 5:32:27 PM UTC-7, Ned Simmons wrote:

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line.


Maybe not so stupid. The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.

The failure rate for a series string of seven is 0.1 of the rate for a string of 70.
And, one string failing doesn't stop the other parallel strings from making light.

Best practice for designing LED fixtures is not compatible with reusing the
fluorescent fixtures unballasted OR with the original fluorescent ballasts.
GE makes LED fluorescent-tube-shaped lamps labeled
"Use only with General Electric LED21T8 DR/.... LED driver"
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On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

On Thursday, September 20, 2018 at 5:32:27 PM UTC-7, Ned Simmons wrote:

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line.


Maybe not so stupid. The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.


Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating. That implies
about 175V across the 75W lamp once it's running. Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful. I'll bet I've spent as
much time over the years replacing ballasts as lamps. I'd rather spend
the time up-front pulling them out.


--
Ned Simmons
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On 9/21/2018 7:36 PM, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

On Thursday, September 20, 2018 at 5:32:27 PM UTC-7, Ned Simmons wrote:

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line.

Maybe not so stupid. The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.

Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating. That implies
about 175V across the 75W lamp once it's running. Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful. I'll bet I've spent as
much time over the years replacing ballasts as lamps. I'd rather spend
the time up-front pulling them out.


Â*My only mistake was ordering the clear instead of frosted , these are
pretty bright and tend to glare a bit . I tested it , and a strip of
(frosted) scotch tape over the center of the clear side of the bulb is
just about right . These are 6000K light temp LEDs , taking a bit to get
used to after having less-than-enough light that was a lot more "yellow" .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On Fri, 21 Sep 2018 19:49:46 -0500, Terry Coombs
wrote:

On 9/21/2018 7:36 PM, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

On Thursday, September 20, 2018 at 5:32:27 PM UTC-7, Ned Simmons wrote:

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line.
Maybe not so stupid. The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.

Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating. That implies
about 175V across the 75W lamp once it's running. Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful. I'll bet I've spent as
much time over the years replacing ballasts as lamps. I'd rather spend
the time up-front pulling them out.


*My only mistake was ordering the clear instead of frosted , these are
pretty bright and tend to glare a bit . I tested it , and a strip of
(frosted) scotch tape over the center of the clear side of the bulb is
just about right . These are 6000K light temp LEDs , taking a bit to get
used to after having less-than-enough light that was a lot more "yellow" .


I ADORE the whiter LEDs and hated the ****-yellow incan color, so it
was an easy swap for me. I sure like the newer pricing on LED fluor
replacement strips but haven't partaken yet.

--
America rose from abnormal origins. The nation didn't grow organ-
ically or gradually from indigenous tribes--like, say, the French
or the Poles--but emerged out of courageous, conscious acts of
will by Pilgrims and Patriots. --Michael Medved, Right Turns
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On Friday, September 21, 2018 at 5:36:05 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

... The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.


Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating.


The LEDs are more efficient, but the ballast still chokes current at circa 425 mA.
So, the voltage is lower for LEDs than for tubes. My '24V' number is only order-of-magnitude.


...Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful.


But, it IS buffering the LEDs from voltage spikes, without the power-wasting resistors
used in some lamp-replace series strings. The starter-boost is a complex part
of the ballast, but isn't required for the LEDs; if it fails, you'll never notice.
The 'internal LED drivers' in the one lamp I dissected, were... only rectifiers to prevent
reverse voltage.


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On 9/22/2018 12:56 AM, John Doe wrote:
If this poster had a brain...

Its "relamping the shop (to save electricity)" would consist of
purchasing a high-quality modern headlamp.

I'm dead serious. Nothing aids vision (while saving HUGELY on
electricity as a SECONDARY benefit) more than a good headlamp.
Couldn't live without mine.


Â* If I were so broke couldn't afford to keep the power on I might do
that too . I didn't relamp to "save electricity" , but to have usable
levels of light . Oh , and if you have to resort to insults , **** off .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On Fri, 21 Sep 2018 20:36:11 -0400, Ned Simmons
wrote:

On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

On Thursday, September 20, 2018 at 5:32:27 PM UTC-7, Ned Simmons wrote:

The LED 8-footers available locally were drop-in replacements for the
fluorescent tubes, i.e., require the ballast to operate. Stupid. The
lamps I purchased connect directly across the line.


Maybe not so stupid. The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.


Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating. That implies
about 175V across the 75W lamp once it's running. Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful. I'll bet I've spent as
much time over the years replacing ballasts as lamps. I'd rather spend
the time up-front pulling them out.

I have read in more than one place that dimmable LED lamps can better
handle power fluctuations. Where I live we have 250 volts most of the
time with occasional excursions above and rarely below 250. So I have
been installinf only dimmable types. Haven't had any failures yet
except for a cheap night light. That wasn't dimmable.
Eric
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On Fri, 21 Sep 2018 22:11:47 -0700 (PDT), whit3rd
wrote:

On Friday, September 21, 2018 at 5:36:05 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

... The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.


Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating.


The LEDs are more efficient, but the ballast still chokes current at circa 425 mA.
So, the voltage is lower for LEDs than for tubes. My '24V' number is only order-of-magnitude.


Which means the LED driver in the tube has to deal with a constant
current source that can deliver up to 750 volts instead of a
well-behaved 120V constant voltage source. Doesn't seem advantageous
to me.



...Now, in addition to
the internal LED driver(s) in the lamp, you have a point of failure,
the ballast, that's not doing anything useful.


But, it IS buffering the LEDs from voltage spikes,


The ballast is intentionally designed to develop a 750V spike.

without the power-wasting resistors
used in some lamp-replace series strings.


I've not seen dropping resistors in the replacement tubes. All I've
seen have switching LED drivers. Look at the specs for the LED
replacement tubes I pointed to. They run on 100-265VAC or 85-265VAC.

The starter-boost is a complex part
of the ballast, but isn't required for the LEDs; if it fails, you'll never notice.


Perhaps for an electronic ballast, not so for a magnetic ballast.

The 'internal LED drivers' in the one lamp I dissected, were... only rectifiers to prevent
reverse voltage.


I don't understand. Why would you need to protect an LED from reverse
voltage?


--
Ned Simmons
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On Saturday, September 22, 2018 at 4:49:35 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 22:11:47 -0700 (PDT), whit3rd
wrote:

On Friday, September 21, 2018 at 5:36:05 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

... The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.

Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating.


The LEDs are more efficient, but the ballast still chokes current at circa 425 mA.


Which means the LED driver in the tube has to deal with a constant
current source that can deliver up to 750 volts instead of a
well-behaved 120V constant voltage source.


A constant current source is ideal for powering LEDs; with the right
size LED (or the right multiplicity of paralleled LEDs) that's useful power.


The ballast is intentionally designed to develop a 750V spike.


Yes, in order to light the cold tube; but, it does that when the tube is NOT
conducting, when that potential 425 mA of current isn't drawn. LEDs
without a 'driver' attached will always draw that current.

I've not seen dropping resistors in the replacement tubes. All I've
seen have switching LED drivers.


Do you mean drivers built into the long tubes? I've never seen that.

Look at the specs for the LED
replacement tubes I pointed to. They run on 100-265VAC or 85-265VAC.

The starter-boost is a complex part
of the ballast, but isn't required for the LEDs; if it fails, you'll never notice.


Perhaps for an electronic ballast, not so for a magnetic ballast.


There's different designs, including some with heaters/neon lamps etc.

The 'internal LED drivers' in the one lamp I dissected, were... only rectifiers to prevent
reverse voltage.


I don't understand. Why would you need to protect an LED from reverse
voltage?


Reverse voltage can create large (surface) electric fields, and move impurities
around. That causes the LED to age, dim prematurely. Forward voltage on
the diode never exceeds 3V, because the diode conducts, and that means the
surface fields are smaller.
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On 9/23/2018 5:34 AM, Jim Wilkins wrote:
"John Doe" wrote in message
news
In fact, there is no better light source than a headlamp. Apparently
some people object because it looks nerdy. Modern headlamps are
extremely light, extremely BRIGHT (choose your color), and
long-lasting, with no need for an external power supply. That's why
"broke" surgeons use them.

Bozo supplies its shop with "what I can afford" instead of what
works.
Bozo needs to learn how to read BIG LETTERS, too, I said saving
electricity
is a "SECONDARY" benefit of using a high-quality modern headlamp.




On 9/22/2018 12:56 AM, John Doe wrote:
If this poster had a brain...

Its "relamping the shop (to save electricity)" would consist of
purchasing a high-quality modern headlamp.

I'm dead serious. Nothing aids vision (while saving HUGELY on
electricity as a SECONDARY benefit) more than a good headlamp.
Couldn't live without mine.


¶ÿ If I were so broke couldn't afford to keep the power on I might
do
that too . I didn't relamp to "save electricity" , but to have
usable
levels of light . Oh , and if you have to resort to insults , ****
off .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

IIRC you don't use machine tools or need to protect yourself from
their flying chips with a face shield.


Â* I doubt he even knows what a "machine tool" is . Most trolls know
very little but what their masters tell them to say .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !



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On Sun, 23 Sep 2018 07:13:09 -0500, Terry Coombs
wrote:

On 9/23/2018 5:34 AM, Jim Wilkins wrote:
"John Doe" wrote in message
news
In fact, there is no better light source than a headlamp. Apparently
some people object because it looks nerdy. Modern headlamps are
extremely light, extremely BRIGHT (choose your color), and
long-lasting, with no need for an external power supply. That's why
"broke" surgeons use them.

Bozo supplies its shop with "what I can afford" instead of what
works.
Bozo needs to learn how to read BIG LETTERS, too, I said saving
electricity
is a "SECONDARY" benefit of using a high-quality modern headlamp.




On 9/22/2018 12:56 AM, John Doe wrote:
If this poster had a brain...

Its "relamping the shop (to save electricity)" would consist of
purchasing a high-quality modern headlamp.

I'm dead serious. Nothing aids vision (while saving HUGELY on
electricity as a SECONDARY benefit) more than a good headlamp.
Couldn't live without mine.


¶ÿ If I were so broke couldn't afford to keep the power on I might
do
that too . I didn't relamp to "save electricity" , but to have
usable
levels of light . Oh , and if you have to resort to insults , ****
off .

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

IIRC you don't use machine tools or need to protect yourself from
their flying chips with a face shield.


* I doubt he even knows what a "machine tool" is .


So far so good. The contraptions he's posted in the past demonstrate a
need to learn how to weld at the very least. He's a dopey slow
learner, so if he ever does learn to weld he'll be old like me by then
and maybe he'll figure out what a great advantage it is to have a
small headlamp on a welding helmet, a headlamp for every other task,
bright shop lighting, bright task lighting, and white walls and
ceiling.

Most trolls know
very little


Same thing you said about me. You're demonstrating your own cognitive
limitations.

but what their masters tell them to say .


LOL Who are these "masters?" It's clear that JD has very few
fabricating skills, limited imagination, and is a top-posting bozo.
His fascination with cordless drills makes me think of how cavemen
might have responded to seeing a bag of marbles. His projects might
impress the least-mechanically inclined high schoolers, but that's
about it. Those are facts. So if you want to insult him, why go beyond
the obvious by posting your own delusions?

BTW, if he lived near me I'd offer to teach him some stuff. First
thing I'd do is walk him over to my 16" gear-head, and set him up with
a big chunk of rubber to turn at high speed while wearing a baggy
protective kimona. Then I'd get him onto welding while using "tactile"
gloves with all the finger tips cut off. After that maybe set him
loose on out of position wrench turning of seized fasteners such that
his teeth are in the line of fire. Only after he gets up to speed on
all that would I show him how to fast charge his drill batteries using
a patch cord into an AC socket.
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On Mon, 24 Sep 2018 15:55:56 -0000 (UTC), John Doe
wrote:

My cordless drill powered electric front wheel drive bike is
probably the lightest electric bike there is for the power and
distance. Some have tried using a drill to power the sprocket, but I
believe mine is the first to use a freewheeling pedal hub. It is
exceptionally versatile and very durable. Now DeWalt produces 9
amp hour batteries for it.

https://www.flickr.com/photos_user.g...27532210%40N04


Your stuff was cute when I first saw it. And I'm generally supportive
of kids even if all they're doing is trying. But you have progressed
little, and spent too much time being annoying and witless.

As someone skilled with machine tools, you can do better?
I won't hold my breath waiting for it.


Among the many things I've built is an entire aircraft. I could never
have gotten any of it done if I'd been too busy uploading pics of
Gillian Anderson and insisting that a headlamp was a substitute for
good shop lighting. WTF?

I agree that this poster knows much more about welding than I ever
will. I spent most of my adulthood learning about computers.


And yet you never learned not to top-post on Usenet.

The
idea it knows more about electricity and charging batteries than I
do is laughable.


I've lived off-grid. And my welding during that period was powered by
inverters and batteries. You are an idiot to pretend you have more
skill than old farts like me. I was doing more impressive fabrication
when I was 14 than you are now. I was sneaking into my dad's garage
when he was at work, and whittling down his puny supply of electrodes,
which he was only superficially ****ed about. I was cobbling together
go carts and mini bikes at the time powered by an old pedal-start
washing machine engine. I knew right away that I needed to learn to
weld, which is something that seems to have escaped you, along with
the fact you could have learned in less time than you've spent yapping
online.

It's tough guy on the Internet chest-thumping went
a little too far.


Then why are you still doing it, feeb? Less annoying witlessness and
more doing and you'd be much farther along. Although I sense you're
not very ambitious, and the main goal is to get some attaboys. Good
luck with that.
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On 9/24/2018 1:17 PM, John Doe wrote:
I post in context when I feel like it, at least when I'm dealing
with non-trolls.

I'm not into production, I am into design.

This tough guy on the Internet continues to beat its chest but fails
to answer my challenge. If it thinks it can do better than my
electric bike design, let's see it...

https://www.flickr.com/photos_user.g...27532210%40N04

No idea what "Gillian Anderson" is about, maybe just another
"fabrication"...


Â* Who exactly are you accusing of "beating his chest" ? And what
"challenge" are you talking about ? As far as your bike thingy , it
takes little imagination and even less skill to drill a few holes in
some stock aluminum plate and gob on the hot melt glue to hold a cable
in place . My chops ? Ain't got none . Unless you count a micrometer
adjust dovetail slide boring head , or maybe a home designed/built taper
attachment for my machine lathe (also micrometer adjust), or possibly
even the 9:1 reduction gear set I made when I was going to build my own
X axis power feed for my milling machine - including cutting the gears .
BTW , none of those projects required the use of a headlamp ...

--
Snag
Yes , I'm old
and crochety - and armed .
Get outta my woods !

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On Mon, 24 Sep 2018 18:17:44 -0000 (UTC), John Doe
wrote:

I post in context when I feel like it,


I'm confident you'll keep doing what you "feel like," no matter how
dumb it is.

at least when I'm dealing
with non-trolls.


You're a dopey top-poster. You're pigheaded to keep doing it.

I'm not into production, I am into design.


Not much design there. In fact, marrying two existing things is
generally the opposite of design. Chocolate and peanut butter
combinations excepted, of course.

This tough guy on the Internet continues to beat its chest but fails
to answer my challenge. If it thinks it can do better than my
electric bike design, let's see it...


Dopey challenge. I stopped being interested in bicycles about 50 years
ago. I found that pretty much any other vehicle expanded my range
quite a bit. Especially aircraft, which tend to have more design and
fabrication requirements in a single sub-system than you've done in
your entire life.

https://www.flickr.com/photos_user.g...27532210%40N04

No idea what "Gillian Anderson" is about,


My mistake, it's the somewhat similar looking Lauren Holly, and a
crotch shot of Maria Sharapova. Are there drill batteries hiding
between her legs? The cat doesn't look impressed at all, time for you
to drill-motorize a cardboard box I guess. The point remains, you can
use your time to yap or to progress. You've made your choice and I'm
happy you're here for me to poop on.

maybe just another
"fabrication"...


Nobody's surprised that you're proving my point by posting more
lameness. Why do you keep adding "free spam" to the group list? Was
that something you learned to do in 'puter school?
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On Mon, 24 Sep 2018 13:59:05 -0500, Terry Coombs
wrote:

On 9/24/2018 1:17 PM, John Doe wrote:
I post in context when I feel like it, at least when I'm dealing
with non-trolls.

I'm not into production, I am into design.

This tough guy on the Internet continues to beat its chest but fails
to answer my challenge. If it thinks it can do better than my
electric bike design, let's see it...

https://www.flickr.com/photos_user.g...27532210%40N04

No idea what "Gillian Anderson" is about, maybe just another
"fabrication"...


* Who exactly are you accusing of "beating his chest" ? And what
"challenge" are you talking about ? As far as your bike thingy , it
takes little imagination and even less skill to drill a few holes in
some stock aluminum plate and gob on the hot melt glue to hold a cable
in place . My chops ? Ain't got none . Unless you count a micrometer
adjust dovetail slide boring head , or maybe a home designed/built taper
attachment for my machine lathe (also micrometer adjust), or possibly
even the 9:1 reduction gear set I made when I was going to build my own
X axis power feed for my milling machine - including cutting the gears .


That was overkill. Pretty sure I was ahead of his skill level when I
built a wishing well out of popsicle sticks in
after-Sunday-School-class.

BTW , none of those projects required the use of a headlamp ...


I love my headlamps. Can hardly believe the improvement it made adding
a small one to my welding helmet. My all-day ones are powered by
18650s. Saves me cleaning the smoke off the overheads as often.


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On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd
wrote:

On Saturday, September 22, 2018 at 4:49:35 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 22:11:47 -0700 (PDT), whit3rd
wrote:

On Friday, September 21, 2018 at 5:36:05 PM UTC-7, Ned Simmons wrote:
On Fri, 21 Sep 2018 12:59:12 -0700 (PDT), whit3rd
wrote:

... The 'require ballast' lamps get about 24V of
excitation, which means seven or eight LED diodes in a series string, with
other strings in parallel. The 'full voltage' get 240V, so that's
seventy or eighty in series.

Where do you get 24V? A standard ballast for 8 foot F96T12 lamps
outputs 750V for starting the lamp and 425mA operating.

The LEDs are more efficient, but the ballast still chokes current at circa 425 mA.


Which means the LED driver in the tube has to deal with a constant
current source that can deliver up to 750 volts instead of a
well-behaved 120V constant voltage source.


A constant current source is ideal for powering LEDs; with the right
size LED (or the right multiplicity of paralleled LEDs) that's useful power.


Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal. And if you implement a single string connected
directly to the ballast, LEDs that'll operate at 425mA are expensive,
require relatively heavy heat sinks, and will present
difficult-to-diffuse bright point sources. Approx 30 LED's vs. 196 in
the replacement tubes I purchased.



The ballast is intentionally designed to develop a 750V spike.


Yes, in order to light the cold tube; but, it does that when the tube is NOT
conducting, when that potential 425 mA of current isn't drawn. LEDs
without a 'driver' attached will always draw that current.

I've not seen dropping resistors in the replacement tubes. All I've
seen have switching LED drivers.


Do you mean drivers built into the long tubes? I've never seen that.

Look at the specs for the LED
replacement tubes I pointed to. They run on 100-265VAC or 85-265VAC.

The starter-boost is a complex part
of the ballast, but isn't required for the LEDs; if it fails, you'll never notice.


Perhaps for an electronic ballast, not so for a magnetic ballast.


There's different designs, including some with heaters/neon lamps etc.

The 'internal LED drivers' in the one lamp I dissected, were... only rectifiers to prevent
reverse voltage.


I don't understand. Why would you need to protect an LED from reverse
voltage?


Reverse voltage can create large (surface) electric fields, and move impurities
around. That causes the LED to age, dim prematurely. Forward voltage on
the diode never exceeds 3V, because the diode conducts, and that means the
surface fields are smaller.


--
Ned Simmons
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On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd
wrote:


A constant current source is ideal for powering LEDs; with the right
size LED (or the right multiplicity of paralleled LEDs) that's useful power.


Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.


Yet, it's done all the time. A 'nine-LED' flashlight with three AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common, also.
Sometimes resistors are added to each string, but not always.
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Terry Coombs wrote:

none of those projects required the use of a headlamp


WRONG!
EVERYTHING requires the use of a headlamp.
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On Tuesday, September 25, 2018 at 12:47:35 AM UTC-4, John Doe wrote:
Terry Coombs wrote:

none of those projects required the use of a headlamp


WRONG!
EVERYTHING requires the use of a headlamp.


Some things require not using a headlamp. Arc welding requires a face mask which precludes the use of a headlamp.

Dan

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On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd
wrote:


A constant current source is ideal for powering LEDs; with the right
size LED (or the right multiplicity of paralleled LEDs) that's useful power.


Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.


Yet, it's done all the time. A 'nine-LED' flashlight with three AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common, also.
Sometimes resistors are added to each string, but not always.


So how do you insure that the current is divided equally among the
strings?

--
Ned Simmons


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"Ned Simmons" wrote in message
...
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd

wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons
wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd

wrote:


A constant current source is ideal for powering LEDs; with the
right
size LED (or the right multiplicity of paralleled LEDs) that's
useful power.

Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.


Yet, it's done all the time. A 'nine-LED' flashlight with three
AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common,
also.
Sometimes resistors are added to each string, but not always.


So how do you insure that the current is divided equally among the
strings?

--
Ned Simmons


They are somewhat self-ballasting, as shown by the I-V curves.
https://www.electronics-tutorials.ws/diode/diode_8.html



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On Tue, 25 Sep 2018 04:38:44 -0700 (PDT), "
wrote:

Arc welding requires a face mask which precludes the use of a headlamp.


Nonsense. I added a headlamp to my welding helmet about a year ago. It
works so well that I'm surprised it isn't a popular commercial
offering for old farts. It improved the view before the arc is struck.
It cured the problem of temporary blindness due to the need for old
eyes to refocus when the arc is first struck. It makes it easier to
use the helmet for grinding. Yesterday I noticed those problems seemed
to be returning somewhat. The light looked Ok but I couldn't remember
when I last swapped the batteries. Put in fresh ones and things
improved again. When I first tried adding a lamp to the helmet, I used
an old 18650 model I had lying around. Nice and bright, but too heavy
and required too many button pushes to switch on and off. Changed to a
smaller one with a simple on/off switch.

In short, a welding helmet light does all the things everybody knows a
welding task light helps with, but puts the light easily right where
it's needed.

BTW, normally I don't share good tips with rightards. I'm making an
exception here because I know that once some of you other old farts
put a light on your welding helmet, it's going to make your teeth
grind every time you remember that such a great improvement came from
an alleged "leftist," who your buddy claimed he was having killed at
least 6 years ago. chuckle
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On Tuesday, September 25, 2018 at 5:54:11 AM UTC-7, Ned Simmons wrote:
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:


...you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.


Yet, it's done all the time. A 'nine-LED' flashlight with three AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common, also.
Sometimes resistors are added to each string, but not always.


So how do you insure that the current is divided equally among the
strings?


I prefer not to do it that way, but for a manufacturer, batch-matching of the
LEDs is the first step. Designing the lamp so that all stay at similar temperatures
is the second. Maybe, too, the LEDs are deliberatelyl degenerated somewhat
(aren't ideal diodes). In similar situations, I've seen fuses used, which both
add series resistance and which prevent a single shorted (failed) unit from
causing a total failure.
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On Tue, 25 Sep 2018 09:15:10 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
.. .
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd

wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons
wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd

wrote:

A constant current source is ideal for powering LEDs; with the
right
size LED (or the right multiplicity of paralleled LEDs) that's
useful power.

Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.

Yet, it's done all the time. A 'nine-LED' flashlight with three
AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common,
also.
Sometimes resistors are added to each string, but not always.


So how do you insure that the current is divided equally among the
strings?

--
Ned Simmons


They are somewhat self-ballasting, as shown by the I-V curves.
https://www.electronics-tutorials.ws/diode/diode_8.html



Unless I'm misintrepeting the curves, or looking in the wrong place,
the graph shows a potential for runaway -- the slope of the curves
increases with increasing voltage.

Here's a similar curve for a tungsten filament, which is
self-ballasting.
https://www.quora.com/What-does-the-...lamp-look-like

This article talks about the hazards of paralleling strings of LEDs.
https://www.ledsmagazine.com/article...-magazine.html

--
Ned Simmons
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On Tue, 25 Sep 2018 12:08:10 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 5:54:11 AM UTC-7, Ned Simmons wrote:
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:


...you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.

Yet, it's done all the time. A 'nine-LED' flashlight with three AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common, also.
Sometimes resistors are added to each string, but not always.


So how do you insure that the current is divided equally among the
strings?


I prefer not to do it that way, but for a manufacturer, batch-matching of the
LEDs is the first step. Designing the lamp so that all stay at similar temperatures
is the second. Maybe, too, the LEDs are deliberatelyl degenerated somewhat
(aren't ideal diodes). In similar situations, I've seen fuses used, which both
add series resistance and which prevent a single shorted (failed) unit from
causing a total failure.


Or you could avoid the work-arounds and potential pitfalls: pitch the
ballasts, and purchase lamps with built-in LED drivers that operate on
line voltage.


--
Ned Simmons


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On Tuesday, September 25, 2018 at 12:41:01 PM UTC-7, Ned Simmons wrote:
On Tue, 25 Sep 2018 12:08:10 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 5:54:11 AM UTC-7, Ned Simmons wrote:
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:


...you can't just connect parallel strings of LED's


Yet, it's done all the time.


Or you could avoid the work-arounds and potential pitfalls: pitch the
ballasts, and purchase lamps with built-in LED drivers that operate on
line voltage.


What kind of 'built-in LED drivers' are you thinking of? Gizmos that
switch OPEN when the current goes too high? Or, complete current-regulated
DC power supplies? Something as reliable as a magnetic ballast is not
going to look like a silicon IC, and take AC line input, and spikes, gracefully.
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"Ned Simmons" wrote in message
...
On Tue, 25 Sep 2018 09:15:10 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
. ..
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd

wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons
wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd

wrote:

A constant current source is ideal for powering LEDs; with the
right
size LED (or the right multiplicity of paralleled LEDs) that's
useful power.

Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.

Yet, it's done all the time. A 'nine-LED' flashlight with three
AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common,
also.
Sometimes resistors are added to each string, but not always.

So how do you insure that the current is divided equally among the
strings?

--
Ned Simmons


They are somewhat self-ballasting, as shown by the I-V curves.
https://www.electronics-tutorials.ws/diode/diode_8.html



Unless I'm misintrepeting the curves, or looking in the wrong place,
the graph shows a potential for runaway -- the slope of the curves
increases with increasing voltage.

Here's a similar curve for a tungsten filament, which is
self-ballasting.
https://www.quora.com/What-does-the-...lamp-look-like

This article talks about the hazards of paralleling strings of LEDs.
https://www.ledsmagazine.com/article...-magazine.html

--
Ned Simmons


Try this:
https://www.cree.com/led-components/...LA1BWKWMKW.pdf

The slope isn't straight like a resistor voltage divider, the reason
I qualified them as "somewhat". It also shows their limited tolerance
for reverse bias.

-jsw


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On Tue, 25 Sep 2018 13:32:13 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 12:41:01 PM UTC-7, Ned Simmons wrote:
On Tue, 25 Sep 2018 12:08:10 -0700 (PDT), whit3rd
wrote:

On Tuesday, September 25, 2018 at 5:54:11 AM UTC-7, Ned Simmons wrote:
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd
wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons wrote:

...you can't just connect parallel strings of LED's


Yet, it's done all the time.


Or you could avoid the work-arounds and potential pitfalls: pitch the
ballasts, and purchase lamps with built-in LED drivers that operate on
line voltage.


What kind of 'built-in LED drivers' are you thinking of? Gizmos that
switch OPEN when the current goes too high?

No.

Or, complete current-regulated
DC power supplies?

Yes. I haven't pulled one apart, but I'm pretty confident that the
replacement tubes I purchased have constant current switching power
supplies.

Something as reliable as a magnetic ballast is not
going to look like a silicon IC, and take AC line input, and spikes, gracefully.


I've been designing, building, and installing automation and machine
tools in industrial settings for 35 years. For most of that time the
bulk of the low power loads in control systems have been powered by
switchers with universal inputs; typically 100-265VAC. I've seen very
few failures, so it's possible to build such supplies that survive in
nasty electrical environments. Another example is electronic
fluorescent ballasts, which are only slightly less reliable than
magnetic ballasts.

The quality of the supplies in LED fluorescent replacements
undoubtedly varies and is a legitimate question, but my experience so
far has been more than satisfactory.

--
Ned Simmons
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On Tue, 25 Sep 2018 18:31:29 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
.. .
On Tue, 25 Sep 2018 09:15:10 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
...
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd

wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons
wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd

wrote:

A constant current source is ideal for powering LEDs; with the
right
size LED (or the right multiplicity of paralleled LEDs) that's
useful power.

Sure, but you can't just connect parallel strings of LED's to a
constant current source and expect the current in the individual
strings will be equal.

Yet, it's done all the time. A 'nine-LED' flashlight with three
AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are common,
also.
Sometimes resistors are added to each string, but not always.

So how do you insure that the current is divided equally among the
strings?

--
Ned Simmons

They are somewhat self-ballasting, as shown by the I-V curves.
https://www.electronics-tutorials.ws/diode/diode_8.html



Unless I'm misintrepeting the curves, or looking in the wrong place,
the graph shows a potential for runaway -- the slope of the curves
increases with increasing voltage.

Here's a similar curve for a tungsten filament, which is
self-ballasting.
https://www.quora.com/What-does-the-...lamp-look-like

This article talks about the hazards of paralleling strings of LEDs.
https://www.ledsmagazine.com/article...-magazine.html

--
Ned Simmons


Try this:
https://www.cree.com/led-components/...LA1BWKWMKW.pdf

The slope isn't straight like a resistor voltage divider, the reason
I qualified them as "somewhat". It also shows their limited tolerance
for reverse bias.

-jsw


Yeah, it's sinking in. Slowly.

--
Ned Simmons
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"Ned Simmons" wrote in message
...
On Tue, 25 Sep 2018 18:31:29 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
. ..
On Tue, 25 Sep 2018 09:15:10 -0400, "Jim Wilkins"
wrote:

"Ned Simmons" wrote in message
m...
On Mon, 24 Sep 2018 19:30:37 -0700 (PDT), whit3rd

wrote:

On Monday, September 24, 2018 at 6:12:23 PM UTC-7, Ned Simmons
wrote:
On Sat, 22 Sep 2018 19:44:42 -0700 (PDT), whit3rd

wrote:

A constant current source is ideal for powering LEDs; with
the
right
size LED (or the right multiplicity of paralleled LEDs)
that's
useful power.

Sure, but you can't just connect parallel strings of LED's to
a
constant current source and expect the current in the
individual
strings will be equal.

Yet, it's done all the time. A 'nine-LED' flashlight with
three
AAA cells
has nine strings of one LED each, in parallel.

Desk lamps with three or four LED strings in parallel are
common,
also.
Sometimes resistors are added to each string, but not always.

So how do you insure that the current is divided equally among
the
strings?

--
Ned Simmons

They are somewhat self-ballasting, as shown by the I-V curves.
https://www.electronics-tutorials.ws/diode/diode_8.html



Unless I'm misintrepeting the curves, or looking in the wrong
place,
the graph shows a potential for runaway -- the slope of the curves
increases with increasing voltage.

Here's a similar curve for a tungsten filament, which is
self-ballasting.
https://www.quora.com/What-does-the-...lamp-look-like

This article talks about the hazards of paralleling strings of
LEDs.
https://www.ledsmagazine.com/article...-magazine.html

--
Ned Simmons


Try this:
https://www.cree.com/led-components/...LA1BWKWMKW.pdf

The slope isn't straight like a resistor voltage divider, the
reason
I qualified them as "somewhat". It also shows their limited
tolerance
for reverse bias.

-jsw


Yeah, it's sinking in. Slowly.

--
Ned Simmons


In the 1980's I designed and built a delicately balanced constant
current string of LEDs, thermistors and Zeners that sensed and
indicated four liquid ink levels in a rotating print head. It was a
finely tuned version of the Low Fuel light in my car. At the time I
understood the components' I-V curves well, but I haven't dealt as
seriously with LEDs since.

The constant current limiter was a depletion mode JFET with its gate
connected to the source like example 7. They were available as
2-terminal devices that looked like diodes.
https://www.quora.com/What-are-Fet-application

-jsw




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On Thu, 27 Sep 2018 21:04:13 -0400, "Jim Wilkins"
wrote:


In the 1980's I designed and built a delicately balanced constant
current string of LEDs, thermistors and Zeners that sensed and
indicated four liquid ink levels in a rotating print head. It was a
finely tuned version of the Low Fuel light in my car. At the time I
understood the components' I-V curves well, but I haven't dealt as
seriously with LEDs since.

The constant current limiter was a depletion mode JFET with its gate
connected to the source like example 7. They were available as
2-terminal devices that looked like diodes.
https://www.quora.com/What-are-Fet-application

-jsw


For Centronics? I recall you mentioning Centronics because in the
early 90's I designed a couple pieces of automation for Presstek in
Hudson NH. Presstek was started by the Howards and many of the
employees had also worked at Centronics.

--
Ned Simmons
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"Ned Simmons" wrote in message
...
On Thu, 27 Sep 2018 21:04:13 -0400, "Jim Wilkins"
wrote:


In the 1980's I designed and built a delicately balanced constant
current string of LEDs, thermistors and Zeners that sensed and
indicated four liquid ink levels in a rotating print head. It was a
finely tuned version of the Low Fuel light in my car. At the time I
understood the components' I-V curves well, but I haven't dealt as
seriously with LEDs since.

The constant current limiter was a depletion mode JFET with its gate
connected to the source like example 7. They were available as
2-terminal devices that looked like diodes.
https://www.quora.com/What-are-Fet-application

-jsw


For Centronics? I recall you mentioning Centronics because in the
early 90's I designed a couple pieces of automation for Presstek in
Hudson NH. Presstek was started by the Howards and many of the
employees had also worked at Centronics.

--
Ned Simmons


Same people, incorporated as "Howtek".

That car, a 78 Accord, had several unusual electrical and mechanical
features I was curious about, such as current-operated reed relays in
series with the brake lights that lit an indicator if a bulb burned
out. Its extremely lean burning CVCC engine gave it ~38MPG on average
and up to 44MPG on a long trip.



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On Saturday, September 22, 2018 at 1:56:12 AM UTC-4, John Doe wrote:
If this poster had a brain...

Its "relamping the shop (to save electricity)" would consist of
purchasing a high-quality modern headlamp.

I'm dead serious. Nothing aids vision (while saving HUGELY on
electricity as a SECONDARY benefit) more than a good headlamp.
Couldn't live without mine.


--

(snipped)

What a wailing ****head. Who ****ed in your cheerios this morning, tough guy?
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