Mohgasm Driver Overheating

[justinjja]

If a mohgasm driver overheats, will it start flashing on and off to protect itself?

I built a 445 laser w/ a 1.8A Mohgasm round driver.
After about 1min runtime the laser start flashing off and on, and the frequency goes up as time goes on.

This is the driver overheating right?

By the way I do have a small heatsink attached to the IC on the mohgasm driver.

 

[DTR]

How about on the resistors? They heat up a great deal on a 1.8A unit.:beer:

 

[justinjja]

How about on the resistors? They heat up a great deal on a 1.8A unit.:beer:

They are soldered to the pcb, I would think that they would be fine.
but anyway I dont think they could cause the flashing

 

[Meatball]

It sounds like its dropping out of regulation for thermal reasons. You need very good heat sinking on those. Try to sink it directly to the host if at all possible!

 

[Mohrenberg]

yeah the flashing is normally a sign of overheating.
What host is this in and how is it heat sinked?

with C6's, i cut off pieces from a 1/8" thick flat aluminum and arctic silver it to the IC, and then put a dab of arctic silver on top of the heat sink right before i press the driver into place. This way the IC is essentially heat sinked to the actual pill.

are you using 2 or 3 lithium batteries?

 

[rhd]

It sounds like its dropping out of regulation for thermal reasons. You need very good heat sinking on those. Try to sink it directly to the host if at all possible!

I keep asking this in a bunch of different threads (sorry to sound like a broken record)

Meatball, have you actually been able to heatsink one of these 1.8A drivers successfully? (to avoid thermal protection kicking in)

I'll point out that I don't own a Mohgasm. But I have a very similar driver (same IC, etc) and it doesn't matter how well I think I've heatsunk (sp?) it, I can't avoid thermal protection kicking in.

I have a working theory that you simply CANNOT adequately heatsink these TO-252 ICs without access to their metal tab (which is of course attached to the PCB).

For the last week, I've been asking anyone who can, to show me a 1.8A driver based on a TO-252 linear 1085 IC that is actually able to avoid thermal protection with heatsinking.

So far, I've only heard people suggesting that they've not been able to pull it off.

 

[Things]

On the topic of failing drivers, the C6 host I got a while ago seems to have died somehow. I went to switch it on, get a bright flash, then it fades to almost nothing. Really not sure if this is a diode or driver fault. I will have my electronics gear in a few days and I can test, though is this another possible failure mode of the driver?

 

[Mohrenberg]

I've got some 1.8s assembled right now, ill test it heatsinked in the pill with an m140 and see how long it lasts.
Will post back with video in about an hour of what happens

 

[Ghostchrome]

yeah the flashing is normally a sign of overheating.
What host is this in and how is it heat sinked?

with C6's, i cut off pieces from a 1/8" thick flat aluminum and arctic silver it to the IC, and then put a dab of arctic silver on top of the heat sink right before i press the driver into place. This way the IC is essentially heat sinked to the actual pill.

are you using 2 or 3 lithium batteries?

I've got an old school 1.8A JAD kit that is set up like that, and it starts strobing at about 45-60 seconds or so. I'm charging my batteries right now, but I'll time it when they get done. I'm using 2x AW 16340 IMRs.

 

[justinjja]

yeah the flashing is normally a sign of overheating.
What host is this in and how is it heat sinked?

with C6's, i cut off pieces from a 1/8" thick flat aluminum and arctic silver it to the IC, and then put a dab of arctic silver on top of the heat sink right before i press the driver into place. This way the IC is essentially heat sinked to the actual pill.

are you using 2 or 3 lithium batteries?

Just 2 batteries.

The heatsink is a small aluminum heatsink designed for a Graphics Card's VRM's.

I am stuck using thermal epoxy vs arctic silver.

But it doesn't happen unless I run the Laser for over a minuite, so It's not an issue, I was just curious

Thanks for the response

 

[Mohrenberg]

i'm going to test it using 2x18650

i'm getting my cam ready

 

[Mohrenberg]

Just ran it on the test load for 4 minutes without it shutting down. Started at 1807mA and by 4 minutes it was reading 1831.
The pill itself was hot, like the hood of a car in the middle of summer but not enough to inflict pain.
I'm going to do the video now, first of it on the testload to confirm output, then a run on the diode itself.

 

[rhd]

Just ran it on the test load for 4 minutes without it shutting down. Started at 1807mA and by 4 minutes it was reading 1831.
The pill itself was hot, like the hood of a car in the middle of summer but not enough to inflict pain.
I'm going to do the video now, first of it on the testload to confirm output, then a run on the diode itself.

Interesting.

Then I'm dead wrong about my theory re: TO-252s

 

[Ghostchrome]

Will a multimeter detect it going into pulse mode?

 

[Mohrenberg]

done!

I ran it for 7 minutes without thermal kicking in using 2x18650 batteries.

Gonna upload video now.

 

[Mohrenberg]

Will a multimeter detect it going into pulse mode?

you'd see the numbers start jumping around like crazy.

The video i'm uploading is of it powering an m140 diode for 7 minutes in a saik heatsink. The heatsink was really hot by the time i stopped, enough to start hurting after a few seconds of holding it.