N cell blu-ray pointer

This is my first attempt at a real pointer with momentary side switch.

I used DX sku.565 as a host for this build. Its a red pointer that runs on two N cell alkalines (DX description says "1*R1 battery", which is incorrect). N cell batteries are the same diameter as AAAs but only 2/3 their length.




The idea was to keep the original diode heatsink and collimating lens. Thermal epoxy was used to hold the PHR-803T in place.

The driver is based on the TPS61200 regulator, which can run from very little voltage (data sheet states 0.3V). I set it to 90 mA drive current and get 63 mW out the front (after the red's original collimating lens).




It's a tight fit, because the diode holder needs to be screwed into the host, but it worked out pretty good.

looks great.

However i would shorten that spring a bit.
It might short to the case when compressed

Nice work!
The spring looks like it surrounds the positive tip of the battery and shouldn't slip.
Great photos, too. Any shots of it running?

Which li-ion battery might be equiv. to 2 N's lengthwise? this is a pretty sweet build that I might like to try to copy, but would rather use rechargeables than N's...

You mentioned the driver is "based on..." where'd you get it from?

This is the regulator I used, digikey carries it I think. Or you can ask TI for samples  

http://focus.ti.com/docs/prod/folders/print/tps61200.html

As the 61200 is a voltage regulator, I used a high-side current monitor (Zetex 1009) to make the circuit regulate current to the LD. Other than that, the circuit is identical to the one from the application notes in the data sheet.

I dont think there is a Li-Ion battery available that is the same length as two N cells. But if you would like to go the rechargeable route, GP (Goldpeak?) makes N size NiMH rechargeable batteries. That would give you about 2.4V with plenty of current available, would be a really good fit for the 61200...

As for the spring, I saved this nifty foamy ring from the original DX pointer that prevents the spring from touching the ground: