Chief Delphi - Running a LED on 6v?

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Re: Running a LED on 6v?

Quote:

Originally Posted by Chriszuma

Yeah, I kinda came up with the idea on the car ride back. It was dark and I wanted to write a calculator program.

You know that you /could/ just write it on your computer and then use a link cable to download it?
Nah, too easy ;)

Re: Running a LED on 6v?

Quote:

Originally Posted by JonBell

You know that you /could/ just write it on your computer and then use a link cable to download it?
Nah, too easy ;)

Yeah, but that would involve having a laptop out, which was not likely to work in a car full to occupancy capacity.

Re: Running a LED on 6v?

Quote:

Originally Posted by Al Skierkiewicz

Chris,
I would not recommend two LEDs in series for this project. As the batteries discharge it is possible to fall below the voltage at which the LEDs will stay lit (i.e. the forward voltage drop of a two standard LEDs is 2v + 2v=4v.) When the battery falls below the "on" voltage, the LEDs will go out. The calculator will continue running down to maybe 3.5 volts or well below the "on" voltage of a white LED with series resistor.
As a matter of fact, I am not sure you will have satisfactory results with the light pipe idea. Before truly modifying the calculator, try breadboarding your idea to see if it works. The angle of lighting on liquid crystal displays can have a huge effect on viewing. Try a flashlight and fiber optic to test your idea before jumping into the LED wiring. You will also find a huge difference in operating time as the LED will consume much more current than the calculator.

Yeah, I've already thought about these things and come up with a few ideas- for the battery drainage problem, i plan to install a switch and use it sparingly. As for the lighting angle, I have yet to work that one out. I might end up actually backlighting the thing, since it would most likely work a lot better. I'm just worried about breaking something while in there, and if you know me, you know how likely that is. I do plan to do sufficient amounts of testing before deciding on my course of action. I don't mess around with $120 calculators. (Now $1200 laptops are a different story. http://zuma.phire.org/pics/biohackerlit.jpg)

If anyone has another idea on how to get a sufficient amount of light onto, under, or across my calculator screen, i'd love to hear it.

EDIT: oh yeah, and it has to look good.

Re: Running a LED on 6v?

Quote:

Originally Posted by Chriszuma

If anyone has another idea on how to get a sufficient amount of light onto, under, or across my calculator screen, i'd love to hear it.

What's wrong with the obvious solution of using a small flashlight? That's always a handy thing to have around. I customarily keep a metal AAA-cell-powered white LED flashlight in my pocket. It not only illuminates calculator screens, but it also lets me read maps and look inside book bags and even find my way in dark rooms. It has come in handy even in the daytime to search the RC pins for little flecks of metal that might be causing a short in our robot's 5v power.

(I've even been known to use it outside at night to help me see where I'm walking, though nights that dark are very rare.)

Re: Running a LED on 6v?

Quote:

Originally Posted by Chriszuma

I might end up actually backlighting the thing, since it would most likely work a lot better.

Some LCD screens are designed for reflective properties not transmissive. Backlight may not buy you anything at all, again you need to experiment.

Re: Running a LED on 6v?

Quote:

Originally Posted by Alan Anderson

Yeah, but the problem there is not only the cargo space it consumes (my pocket space is at a premium already) but that it is really hard to type effectively with a flashlight in your mouth. It might not be a bad idea to somehow draw voltage out of the usb port (or add a seperate connector) and make a sort of flexi-light.

Re: Running a LED on 6v?

Quote:

Originally Posted by Chriszuma

It might not be a bad idea to somehow draw voltage out of the usb port (or add a seperate connector) and make a sort of flexi-light.

Um...they sell those things already. I bought two of them at a dollar store last year.

Re: Running a LED on 6v?

Quote:

Originally Posted by Chriszuma

USB lamps are available at Best Buy

Re: Running a LED on 6v?

One thing though: since it is in fact a peripheral, and uses the moni-b style connector, I don't know if it actually supplies any voltage to the port. In fact, I kinda doubt it. Anyone know for sure? I currently don't know where my voltmeter is.