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LED no resister question

I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not.

I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible. The units will be powered up only
intermittently, maybe only a few seconds at a time, as a strike is
being detected. I know I am exceeding the current but I don't think
there's enough juice in these little batteries to kill them. But I
don't know.

The color is not that important so if a different color would work
better that's ok.

If you have any suggestions for me It will be greatly appreciated.
 
J

John Popelish

Jan 1, 1970
0
I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

Any chemical cell has some internal resistance that limits
the current it can supply to a load. You are relying on
this resistance to limit the current to your LED. Smaller
cells have higher resistance.
I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible.
(snip)

I doubt that you understand how small a resistor can be.
Resistors are available that are difficult to pick up
without fine pointed tweezers. They have an insignificant
size, compared to either the LED or the cells.
The color is not that important so if a different color would work
better that's ok.

Bluer LEDs use up more voltage (short wavelength photons
have higher energy, and that energy is directly related to
the voltage needed to produce them), and might be a better
match to your two cell battery. However, you may get a
reasonable output from a red LED with a single 1.5 volt cell
and that would save a lot more size than eliminating a resistor.
 
O

Old Mac User

Jan 1, 1970
0
If you had a problem with the short life of the air-zinc cells, you'll
have a much bigger problem if you try to light an LED without
a series resistor. Life = microseconds. OMU
 
J

James Thompson

Jan 1, 1970
0
I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not.

I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible. The units will be powered up only
intermittently, maybe only a few seconds at a time, as a strike is
being detected. I know I am exceeding the current but I don't think
there's enough juice in these little batteries to kill them. But I
don't know.

The color is not that important so if a different color would work
better that's ok.

If you have any suggestions for me It will be greatly appreciated.
Depends on the led and one may work without failing on 3 volt from the
battery you have while others will fail. Look at the specs for forward
voltage of the led and pick one that has close to 3 volt fv. The high
intensity ones can run with 3.5 volt and would do just fine on 3 volt.
 
D

Dan Akers

Jan 1, 1970
0
I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not. <snip>
_________________________________________________________________________________
Re;
Just a thought, but have you considered using an audible indicator?
There are some pretty small piezo buzzers with all sorts volume levels
available that could easily fit the handle of a fishing rod...

Dan Akers
 
R

redbelly

Jan 1, 1970
0
I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not.

I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible. The units will be powered up only
intermittently, maybe only a few seconds at a time, as a strike is
being detected. I know I am exceeding the current but I don't think
there's enough juice in these little batteries to kill them. But I
don't know.

The color is not that important so if a different color would work
better that's ok.

If you have any suggestions for me It will be greatly appreciated.

As John P said, the internal resistance of the batteries is limiting
the current. You can buy commerical keychain lights that connect an
LED directly to two lithium coin cells (2 x 2016). The lithium cells
seem to have enough resistance to limit the current; I've measured up
to 50 mA or so on fresh batteries, but as the batteries wear down so
does the LED current.

As long as you're experimenting with different battery types, you might
try measuring the current for fresh, half-way used, and nearly-spent
batteries. Try to determine what the LED is going through during
actual use. If you don't have a sensitive enough ammeter, add a 1 ohm
or 1/2 ohm resistor to the circuit and measure its voltage (assumin you
have a DMM that will measure to the nearest couple of mV or better).
Of course, you'd remove the resistor in the final product.

Regards,

Mark
 
I doubt that you understand how small a resistor can be.
Resistors are available that are difficult to pick up
without fine pointed tweezers. They have an insignificant
size, compared to either the LED or the cells.

Thank you for your respose. No I don't know how small they can be. I'm
no electronics whiz but I do learn. Where would I find the small type?
Bluer LEDs use up more voltage (short wavelength photons
have higher energy, and that energy is directly related to
the voltage needed to produce them), and might be a better
match to your two cell battery. However, you may get a
reasonable output from a red LED with a single 1.5 volt cell
and that would save a lot more size than eliminating a resistor.
I have experimented with different types and I must use the clear lens
high intensity or wide angle to have them emit enough light in
daylight. I have not got one to light up with a single 1.5v cell

Thanks again
Dennis
 
D

default

Jan 1, 1970
0
I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not.

I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible. The units will be powered up only
intermittently, maybe only a few seconds at a time, as a strike is
being detected. I know I am exceeding the current but I don't think
there's enough juice in these little batteries to kill them. But I
don't know.

The color is not that important so if a different color would work
better that's ok.

If you have any suggestions for me It will be greatly appreciated.

Use a 1/10 watt resistor or chip resistor they weigh very little -
will increase the battery life and perhaps the led life.
 
J

John Popelish

Jan 1, 1970
0
Thank you for your respose. No I don't know how small they can be. I'm
no electronics whiz but I do learn. Where would I find the small type?
(snip)

Digikey and Mouser are distributors that carry thousands of
different resistor types and sizes. Both have search
engines that let you narrow the choices.

The smallest with wire leads would be 1/8th watt types,
(about 1/4 inch long and 1/16th inch in diameter) and 1/4
watt (.1 inch diameter by .3 inch long) but there are
surface mount (SMT) that are tiny rectangles with no leads
as small as .02 by .01 inch. That ought be small enough.
 
D

DJ Delorie

Jan 1, 1970
0
John Popelish said:
I doubt that you understand how small a resistor can be. Resistors are
available that are difficult to pick up without fine pointed tweezers.

The 01005 size is difficult to pick up *with* fine pointed tweezers.
They're about 0.016" long and 0.008" wide:

http://www.delorie.com/pcb/first.html

(the IC in that photo is a TVSOP-14, with 0.4mm pitch)
 
On 18 Oct 2006 11:18:09 -0700 said:
Re;
Just a thought, but have you considered using an audible indicator?
There are some pretty small piezo buzzers with all sorts volume levels
available that could easily fit the handle of a fishing rod...

Dan Akers
I do have an audible indicator model that fits on the rod tip only
slightly larger than the LED unit. It uses the same 1.5v cells as the
LED unit. It holds 2 to 6 cells allowing volume to be adjusted. The
peizo beeper is 12 mm dia. A reviwer wrote about this piezo:

Reviewer: Jonathan Broadwell from BEECH GROVE, IN US
Low/Medium loudness, and 4kHz seems about right. Only pulls 2mA at 5v. Nice change from using led's to debug logic ports...

I found a smaller piezo thats 9mm dia but I have to travel to
China/Tiawan to get one.

http://www.hitpoint.com.tw/electronic/en/product/pb-series/pb-09n23p-01.htm

I must keep this deice as small and as light as I have it now (or
smaller) or No one will ever buy them.

Thank You for your post. I respect every reply I get.

Dennis
 
D

default

Jan 1, 1970
0
Thank you for your respose. No I don't know how small they can be. I'm
no electronics whiz but I do learn. Where would I find the small type?

I have experimented with different types and I must use the clear lens
high intensity or wide angle to have them emit enough light in
daylight. I have not got one to light up with a single 1.5v cell

Thanks again
Dennis

This web site has a schematic for a white led from a 1.5 volt source
that can fit in the base of a miniature screw bulb,

http://cappels.org/dproj/ledpage/leddrv.htm

When it comes to visibility in daylight . . . look for "high flux
leds" generally speaking . . . these are leds with high output and
high beam angles - the half power points are 120 degrees wide unlike
"normal" 13 billion millicandlella lamps with only a 10 degree beam
spread.

I found some surplus ones for 10 cents each on line - they had huge
quantities - the only problem I could see were some of them were
yellow and some tended more towards orange but the difference was only
visible with two adjacent leds and not a problem in the 45 LED matrix
I was making.
 
A

Alan B

Jan 1, 1970
0
I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible.

Resistors can be had in really small packages, especially low Watt
applications like this. It's a better design to use one, and it will
actually save drain on the battery. I see that these points have already
been addressed, so take this as a reinforcement of those opinions.
 
I have a new product I invented. It's a LED fish strike indicator.

I want to thank everyone who replied. You all have been a great help I
also like to give help on these newsgroups when I find a topic I know
something about.

Look for The Snooze Master on sporting goods shelves by the fall of
2007.

Thanks again
Dennis
 
E

Eric R Snow

Jan 1, 1970
0
I want to thank everyone who replied. You all have been a great help I
also like to give help on these newsgroups when I find a topic I know
something about.

Look for The Snooze Master on sporting goods shelves by the fall of
2007.

Thanks again
Dennis
Greetings Dennis,
Lithium coin batteries were mentioned by another poster. You may find
that only a single cell would work for your project. Lithium batteries
may end up having a longer useful life while being lighter than
batteries using different chemistries. Try this link for some info on
lithium batteries: http://www.powerstream.com/Pli.htm I'm not
affiliated with the company in any way.
Cheers,
Eric
 
D

Don Klipstein

Jan 1, 1970
0
I have a new product I invented. It's a LED fish strike indicator.

As I found out experimenting with LEDs, getting the proper current is
the key. My product uses two 5.8mm dia. button batteries. I first used
two #10 air zinc hearing aid batteries (1.4v, 90 mAh) but found out
they only last 90 days after you pull the tab off whether you use them
or not.

I now am going to try two Energizer # 379 type alkaline, (1.5v,
14.5 mAh, 5.8mm dia.) Do you think these will work powering a wide
angle red LED or similar type without eventually frying the LED? The
air zincs are working and I have, so far , not fried any LEDs with
this setup.

I don't want to use a resistor because the unit fits on the end of a
rod tip and I must keep them as small and light and as easy to
manufacture as possible. The units will be powered up only
intermittently, maybe only a few seconds at a time, as a strike is
being detected. I know I am exceeding the current but I don't think
there's enough juice in these little batteries to kill them. But I
don't know.

The color is not that important so if a different color would work
better that's ok.

If you have any suggestions for me It will be greatly appreciated.

For reliability's sakes, I do advise a resistor. Although survival rate
of an LED on a series string of two or three smaller size smaller
diameter 1.5V "button cells" (2 for red to yellow-green, 3 for
non-yellowish green-blue-white) is high. Also, it is fairly common for
LED "keychain"/"keyfob" lights to have a smaller size lithium cell with a
red, orange, or yellow LED or two of such cells in series with a
non-yellowish-green, white or blue one.

Keep in mind the size of a 1/8 watt resistor of a through-hole type
(with leads) - slightly smaller than a 1N914/1N4148 diode!

If you want a really compact resistor to use with a really compact LED,
how about a 1/10 watt surface mount resistor which is 0603 size, and an
LED of same size? Of course, those are surface mount parts and lower cost
mass production requires some sort of PCB to mount these parts onto - but
0603 size parts are of a size only somewhat on the large size of fleas!

(I do advise against using an 0603 size LED without a resistor even
where a 3 mm [T1] or T1-3/4 [5 mm] LED with leads does work without a
resistor! Just keep in mind how inexpensive 0603 size 1/10 watt resistors
are!)

- Don Klipstein ([email protected])
 
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