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Rhith has a valid point, in that the circuit interruption would cause a momentary current flow through the transistor. The alarm would have to have a latch circuit such that once turned on by current flow, it would remain in the ON state until it's preset timer ran through enough clock cycles.

Daedal.... Thanks for the very thorough explanation! Thanks also to Benm, chimo, Gazoo, CHP for their insight. Theory discussions such as this are healthy for airing different ideas and solidifying exactly what's going on in our regulator / diode circuits. I learned a few things anyway, which...

Pseudo... did those beans ever finish cooking?

Haha.. you read my mind. My 0.1uF tantalums are in now as well as my 2.2uF caps.

Re: ** IT'S OFFICIAL **  Laser Power Meter GB I am interested in one if the 2nd GB is in progress. Daedal, are you still gathering to get enough for GB #2?

While we're on the subject (I don't think this is too far afield), Daedal chose 47uF because it was on his proto board at the time. What is considered the smallest capacitance for diode protection? I know someone stated they were happy with 10uF. How much of a pulse are we protecting against?

Discount doesn't apply to the PPL series, only RPL iirc.

I like that solution. Thanks!

This was my only concern... a capacitor discharging through the diode unlimited by an external resistor. That and trying to understand Sam's warning about capacitors placed after the final current limiting resistor. Thanks for the explanation.

If Sam's warning is valid, wouldn't a small resistor in series with the capacitor eliminate his concern? (the resistor/capacitor pair soldered across the diode) When the circuit is initially powered, it would seem as if the capacitor would begin charging until the voltage rises to the forward...

Funny twist... DX charges $120 on their $200mW. Nice find.. thanks!

http://www.repairfaq.org/sam/lasercn2.htm#cn2hbl

I've been thinking about the various circuits I see posted utilizing LM317 as a current driver for laser diodes. All looks great until I look at that capacitor sitting in parallel across the laser diode. I see the potential for disaster there should battery / switch connection transients occur...

Black, definitely.

Re: GB feeler laser barrels It's easy to add a little length to a CR123 if a housing is designed to allow RCR123's, but not so easy the other way around. If people are thinking 123's, that would be something to consider. Count me in for 3.

Re: Crossfire "Re-review" Part 1 They already locked the thread before it could get into a finger wagging contest. The thread owner took a photo showing the laser and a few inches of beam travel, compared it in MS Paint using the "straight line tool" and concluded the beam is perfectly...

I'm guessing any school short of College would consider this a weapon and come down hard. I wouldn't even show this to a teacher unless it was not on school grounds and you knew the teacher was very cool. If you do sell one of these, make sure you would trust the person buying it to treat it...

Has anyone tried modding one of these for a red GB laser? http://www.dealextreme.com/details.dx/sku.5280 Are there any good DX choices for a 3xAAA (large enough head for an AixiZ module and resistor or driver board?) Do the 1W luxeons have a driver easily modified with a resistor to make...

Stands for Do Not Disturb. (Ok.. you got me. Dungeons & Dragons, a 1970's created creative fantasy game using dice, pen and paper, and the imagination.)

I just picked up a few pieces and parts from him. Very nice selection... Thanks!