Is there a good way to pick diodes by forward voltage?

[koolksmart]

I have some pen hosts lying around that I'm itching to put together, but as I'm pouring through my diodes, I'm realizing they're all around 6V minimum forward voltage. The hosts I have can tolerate 2xAAA, so as far as I know I'm limited to ~3V.

Have any of you run into similar issues? The best idea I've come up with from here is just trying to find diodes I like that happen to want 3V, though I don't know of any places that make it easy to sort products as such.

Otherwise I'm looking at using some specific boost converters I imagine. I'm having trouble finding decent ones that are about the width of a AAA so that it'll fit in the host.

Any input?

 

[Rivem]

I have some pen hosts lying around that I'm itching to put together, but as I'm pouring through my diodes, I'm realizing they're all around 6V minimum forward voltage. The hosts I have can tolerate 2xAAA, so as far as I know I'm limited to ~3V.

Voltages generally have to do with the semiconductor materials (different wavelengths) of the diode, so you generally won't see huge differences between diodes of the same wavelength and mode design. Usually, the lower the wavelength, the higher the Voltage (bigger semiconductor bandgap)

That said, 6V is a somewhat unusual spec. What diodes are you dealing with? Is this with a driver? Most linear drivers require extra voltage (called dropout voltage).

Have any of you run into similar issues? The best idea I've come up with from here is just trying to find diodes I like that happen to want 3V, though I don't know of any places that make it easy to sort products as such.

Otherwise I'm looking at using some specific boost converters I imagine. I'm having trouble finding decent ones that are about the width of a AAA so that it'll fit in the host.

Any input?

Get 10440 lithium rechargeables. They're about the same size as AAAs and have a higher voltage. You'd get 6-8.4V out of two. My 405nm laser takes them just like this. It's got a Groove 2 driver.

 

[koolksmart]

I actually have some 10440's coming in the mail (they're taking weeks, ugh). They're my saving hope in my pen laser endeavor (did manage to make a 1W 440nm in a laser66 pen case earlier tonight though!).

The couple of diodes I looked at earlier in particular were OSRAM 450nm 1.6W and OSRAM PL450B 450nm.

I've got some others lying around that are in the 6-9V range, so fingers crossed that these 10440's are gonna deliver everything I'm hoping for. Otherwise I might actually have to put my electrical engineering education to work

 

[Pman]

I'm a bit confused as it sounds like all you need are a boost driver and a single 10440 (with a spacer if you need the length of 2 cells):
http://laserpointerforums.com/f39/x-drive-x-boost-88589.html
Have you looked at a lot of the pen builds here? There are a LOT of them. If you give the specific diode you want to use we can recommend the correct driver to go with it depending upon the output you would like to achieve. Congrats on what sounds like a successful leadlight/laser66 build.
Look in the 445nm section for builds that are more like what it sounds like you want to achieve such as:
http://laserpointerforums.com/f65/ndb7242e-diode-build-96670.html
http://laserpointerforums.com/f65/finished-laser66-laser-pen-w-led-indicator-96151.html
http://laserpointerforums.com/f65/pltb-450b-laser66-build-led-indicator-96212.html

Best batteries I know of for 10440 are the Efest ones:
Efest IMR 10440 350mAh - RTD vapor
You can make your own specific length battery spacer by cutting the length you need from a piece of round aluminum and just putting a layer of shrink wrap around it. Really inexpensive for a few feet of it at a hardware store such as Lowes or Home Depot or whatever.

 

[Lifetime17]

Hi,
There are plenty of pen builds here in the search area like Pman said.. here's a one cell build with that dummy cell from a 1/4in. AL rod..