Weird.

mfo said:

Ok. I was playing with my LPC-815 LOC yesterday. I'm driving it with a Rkcstr @ 400mA. I'm using the 3405 host by jayrob. This host has a big heat sink but I limit my duty cycle to a minute or two tops. Anyhow I was in a dark room just pointing it at my ceiling waving it around. It was focused to infinity. After about a minute I noticed it started to pulse! At first I thought this was some kind of illusion because I was also messing with my GLP 473 that I just received from Glenn's GB. So my red will pulse after having it on for a minute or so. I'm guessing heat could be the cause? I'm stumped on this one.

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nikokapo said:

This exact same thing happens with some Romisen L-C030 I got from DX, but sadly I can't extrapolate the experience because yours is a semiconductor and mine are DPSS. My first guess is heat, somehow it makes a component "slow down". It's one of the mysteries I've never solved.

The weird thing is that the pulsing happens when the laser is turned on from a cold start; I mean, it doesn't start to pulse after some minutes, it starts pulsed and then it settles.

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mfo said:

Very strange. I'm guessing the driver is getting too warm? The driver is housed inside of the aixiz module. Strangeness!

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brtaman said:

Did you check the battery voltage?

I would say that their voltage dropped to a point where the regulator fell out of regulation and started pulsing. It is the only "active" thing within the laser.

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brtaman said:

Did you check the battery voltage?

I would say that their voltage dropped to a point where the regulator fell out of regulation, which caused the strange pulsing. It is the only "active" thing within the laser.

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HIMNL9 said:

LM based ICs have a thermal protection, but usually don't pulse ..... it shut down the IC when junction reach 125C, and re-enable it when the temp go down til 65C ..... too large hysteresis for cause pulsations .....

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HIMNL9 said:

Sorry ..... LM = LM117 / LM family of ICs ..... IC = Integrated Circuit (regulator, in this case) ..... the "rkcstr" drivers uses them.

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HIMNL9 said:

Uhm, no, i doubt this ..... as i said, the hysteresis from the different temperatures is a bit too high for cause a quick pulse ..... can be the case if, as example, the pulses are seconds long, like 10 or 15 seconds on and off .....

BTW, do you use protected li-ion batteries ?

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HIMNL9 said:

Uhm, no, i doubt this ..... as i said, the hysteresis from the different temperatures is a bit too high for cause a quick pulse ..... can be the case if, as example, the pulses are seconds long, like 10 or 15 seconds on and off .....

BTW, do you use protected li-ion batteries ?

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HIMNL9 said:

LM based ICs have a thermal protection, but usually don't pulse ..... it shut down the IC when junction reach 125C, and re-enable it when the temp go down til 65C ..... too large hysteresis for cause pulsations .....

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HIMNL9 said:

There is another possibility, but is strange ..... i mean, you're using two unprotected and one protected cell ..... if the protected cell is at low charge limit (or if is defective or at the end of his life cycle), with the load of the laser it can go under the protection limit, and the protection circuit open the connection (same as turn off the laser), and there, with no load, the battery go up a bit, and the protection circuit close again the connection (and turn it on), and so on, cyclically ..... this can cause the pulsed work ..... usually it don't happens, but can be this the problem ..... you don't have another unprotected battery, or a different one, for try ?

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