raggie33
*the raggedier*
- Joined
- Aug 11, 2003
- Messages
- 13,559
will they ever make leds that run at 1.5 volts. amd is that even praactcal?
will they ever make leds that run at 1.5 volts
- Thread starter raggie33
- Start date
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HarryN
Flashlight Enthusiast
Hi Raggie - I am pretty sure the answer is no, at least for visible light. It might be possible to make an Infra Red LED run off of 1.5 V though.
Now, there actually is a way to "engineer" around this problem. A clever EE could build a small boost circuit into the LED package and it would "appear" to use 1.5 V.
This is not so hard as it sounds, as many ICs do similar things internally to provide multiple voltages from a common external voltage. Doing this for a 5mm LED running 20ma would be a reasonable task. The same project for 1 amp and a Lux III, a little more challenging.
Now, there actually is a way to "engineer" around this problem. A clever EE could build a small boost circuit into the LED package and it would "appear" to use 1.5 V.
This is not so hard as it sounds, as many ICs do similar things internally to provide multiple voltages from a common external voltage. Doing this for a 5mm LED running 20ma would be a reasonable task. The same project for 1 amp and a Lux III, a little more challenging.
ACMarina
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
I would think that it would just take some more engineering. Maybe current technology is limiting, but with science and everything advancing the way it is I think I can say that there will either be an LED or something awfully like one that works with 1.5V. .
I would think that it would just take some more engineering. Maybe current technology is limiting, but with science and everything advancing the way it is I think I can say that there will either be an LED or something awfully like one that works with 1.5V. .
greenLED
Flashaholic
Re: will they ever make leds that run at 1.5 v
/ubbthreads/images/graemlins/takeit.gif
/ubbthreads/images/graemlins/takeit.gif
billw
Enlightened
Re: will they ever make leds that run at 1.5 v
[ QUOTE ]
ACMarina said:
I would think that it would just take some more engineering. Maybe current technology is limiting,
but with science and everything advancing the way it is I think I can say that there will either
be an LED or something awfully like one that works with 1.5V. .
[/ QUOTE ]
Well, there are incandescent light bulbs that work on 1.5V...
But you run into physics. You're essentially converting a electron energy level
and emitting a photon, so the photon ends up with the energy of the
difference in voltage levels of the electron.
So you've got Einstein saying E = hf, and some interesting (?) units issue to measure E in
electron volts instead of Joules ( h = 4.136e-15 eV-s )
<font class="small">Code:</font><hr /><pre>
1.5 V = 4.136e-15 * c / lambda
lamda = 4.136e-15 eV s * 3e8 m/s / 1.5 V
= 8.272e-7 m
= 827.2 nm
</pre><hr />
Which is well into the infrared.
(substitute in our lovely 3.6V voltage drop for modern LEDs and you get
lambda = 4.136e-15 eV s * 3e8 m/s / 3.6V = 345nM
Rather ultraviolet, but don't forget we won't be 100% efficient.)
BillW
[ QUOTE ]
ACMarina said:
I would think that it would just take some more engineering. Maybe current technology is limiting,
but with science and everything advancing the way it is I think I can say that there will either
be an LED or something awfully like one that works with 1.5V. .
[/ QUOTE ]
Well, there are incandescent light bulbs that work on 1.5V...
But you run into physics. You're essentially converting a electron energy level
and emitting a photon, so the photon ends up with the energy of the
difference in voltage levels of the electron.
So you've got Einstein saying E = hf, and some interesting (?) units issue to measure E in
electron volts instead of Joules ( h = 4.136e-15 eV-s )
<font class="small">Code:</font><hr /><pre>
1.5 V = 4.136e-15 * c / lambda
lamda = 4.136e-15 eV s * 3e8 m/s / 1.5 V
= 8.272e-7 m
= 827.2 nm
</pre><hr />
Which is well into the infrared.
(substitute in our lovely 3.6V voltage drop for modern LEDs and you get
lambda = 4.136e-15 eV s * 3e8 m/s / 3.6V = 345nM
Rather ultraviolet, but don't forget we won't be 100% efficient.)
BillW
HarryN
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
There actually is at least one other way to do this by using non-linear optical crystals. These are not so commonly found in everyday life, but are fairly common in the laser world.
I will not claim to understand just how they work, but basically, you put in a wavelength, such as 900nm (IR) in one end, and out comes 450nm (roughly deep blue) from the other. It is pretty slick technology, but not especially efficient.
There actually is at least one other way to do this by using non-linear optical crystals. These are not so commonly found in everyday life, but are fairly common in the laser world.
I will not claim to understand just how they work, but basically, you put in a wavelength, such as 900nm (IR) in one end, and out comes 450nm (roughly deep blue) from the other. It is pretty slick technology, but not especially efficient.
ACMarina
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
billw, I don't know anything about all of the equations, as my physics education is very basic in the electronics area. I simply push the button and light comes out.
Anyway, LEDs seem to work (from my understanding) by having electrons jump. Seems to me, they'll just have to find a material or something that lets them jump the way they need with half the voltage they use now. There are probably serious flaws in this thought process, and I can imagine that to make this happen there may need to be some serious design changes. Possibly so many as to say that it's not even an LED by definition.
I think there will be some sort of electronic critter that produces light, runs on 1.5v and isn't a bulb by definition. Just a guess, though /ubbthreads/images/graemlins/wink.gif
billw, I don't know anything about all of the equations, as my physics education is very basic in the electronics area. I simply push the button and light comes out.
Anyway, LEDs seem to work (from my understanding) by having electrons jump. Seems to me, they'll just have to find a material or something that lets them jump the way they need with half the voltage they use now. There are probably serious flaws in this thought process, and I can imagine that to make this happen there may need to be some serious design changes. Possibly so many as to say that it's not even an LED by definition.
I think there will be some sort of electronic critter that produces light, runs on 1.5v and isn't a bulb by definition. Just a guess, though /ubbthreads/images/graemlins/wink.gif
3rd_shift
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
I thought I saw some 1.5 volt rated infrafrared leds somehwere.
Maybe I was dreaming.
Be kinda cool to run one direct off a regular alkaline battery and see it with nightvision gear.
Could make good campsite/perimeter markers for military use.
I thought I saw some 1.5 volt rated infrafrared leds somehwere.
Maybe I was dreaming.
Be kinda cool to run one direct off a regular alkaline battery and see it with nightvision gear.
Could make good campsite/perimeter markers for military use.
VidPro
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
ohh all that math stuff.
all they have to do is make a gate that triggers low, then use phosphors that can be triggered by it.
(dont know how it works either, but that might be a possibility)
ohh all that math stuff.
all they have to do is make a gate that triggers low, then use phosphors that can be triggered by it.
(dont know how it works either, but that might be a possibility)
Ray_of_Light
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
As BillW mentioned, the Vf of the LED is tied to the output wavelength, and there is pretty much nothing that can be done there.
The suggested use of pumping crystals is highly inefficient... and really expensive.
It is possible to build very small and efficient micro- stepup converter without the use of an inductor, by using a diode-capacitor voltage multiplier scheme, which could be "embedded" in a 5 MM LED with no problem.
Anthony
As BillW mentioned, the Vf of the LED is tied to the output wavelength, and there is pretty much nothing that can be done there.
The suggested use of pumping crystals is highly inefficient... and really expensive.
It is possible to build very small and efficient micro- stepup converter without the use of an inductor, by using a diode-capacitor voltage multiplier scheme, which could be "embedded" in a 5 MM LED with no problem.
Anthony
IsaacHayes
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
Click here for the thread about the 1.5v led with built in step up voltage. These weren't that bright at all, and had tons of blue cast to their beam, and wouldn't light on 1.2 volts so their usefullness isn't that great. A RED one though might be as you could plop it into a solitare and it would be pretty bright.
I modded mine I got from larry into a nifty little marker light running on 2xAAA's. I don't care about the bluish beam because it's just for getting attention. I like the color /ubbthreads/images/graemlins/grin.gif
Click here for the thread about the 1.5v led with built in step up voltage. These weren't that bright at all, and had tons of blue cast to their beam, and wouldn't light on 1.2 volts so their usefullness isn't that great. A RED one though might be as you could plop it into a solitare and it would be pretty bright.
I modded mine I got from larry into a nifty little marker light running on 2xAAA's. I don't care about the bluish beam because it's just for getting attention. I like the color /ubbthreads/images/graemlins/grin.gif
Re: will they ever make leds that run at 1.5 v
Until they get the cost of a tiny boost circuit down to under a few dollars unless you want a really small light an external boost circuit is more cost efficient AND allows you to replace /upgrade the LED without paying the cost of a new circuit inbedded within. Personally I would rather they first make smaller boost circuits to mount on external boards and when they can imbed them in LEDs for pocket change it would be a no brainer. I don't see much use for a l.5v LED boost light that conks out at 1.2v, perhaps .8v would be ok for cutoff voltage.
Until they get the cost of a tiny boost circuit down to under a few dollars unless you want a really small light an external boost circuit is more cost efficient AND allows you to replace /upgrade the LED without paying the cost of a new circuit inbedded within. Personally I would rather they first make smaller boost circuits to mount on external boards and when they can imbed them in LEDs for pocket change it would be a no brainer. I don't see much use for a l.5v LED boost light that conks out at 1.2v, perhaps .8v would be ok for cutoff voltage.
IsaacHayes
Flashlight Enthusiast
Re: will they ever make leds that run at 1.5 v
I didn't try it with recharables, or maybe I did, I don't remeber the outcome. But at 1.2v on alkaline it didn't light. I think on the recharable it did light but it was very dim and started to strobe out of regulation.
I didn't try it with recharables, or maybe I did, I don't remeber the outcome. But at 1.2v on alkaline it didn't light. I think on the recharable it did light but it was very dim and started to strobe out of regulation.
