Labby Enclosure Suggestions

I'm looking for a labby- style enclosure suitable to house an LPC-815 LOC mounted into the side panel with a focusing module. I'm planning on pinning the axis module in place using two dark horse black anodized heatsinks, one on the outside of the enclosure, one on the inside, with the axis module running through them both. The enclosure should also have room for a small cpu cooling fan and the two DDL-style drivers for the fan and LD.

Is it necessary to use the case as a heatsink in this scenario? Or will the two dark horse heatsinks be enough? I plan on giving the LOC LD about 420mA.

This should make the difference between using black abs plastic, or aluminum. Any suggestions for good enclosures?

If I run a ddl style lm317- based driver between the 300mA-450mA range, is it necessary to heatsink the IC package?

I have made a LOC labby here on this section on the forum, i used a LOC-815 @ 420mA with a heat sink about the same size as DH sinks. You should be fine with that heat sink, and i have a small cpu fan, all ran off a 12V 1A power supply.

You'll definitely want to heatsink the LM317 at those current levels.

Thanks for the help guys! Ok so heatsinking to the chassis shouldn't be necessary then... about the small cpu fan, should i focus its airflow more around the LD module? Or around the LM317s?

You could do both ways, i had the fan act as an exhaust and pulled air from around the driver, which does create the most heat IMO, Yeah defiantly sink the LM317 with some sort of aluminum/copper. You should be fine then

meatballofall said:

This should make the difference between using black abs plastic, or aluminum. Any suggestions for good enclosures?

If I run a ddl style lm317- based driver between the 300mA-450mA range, is it necessary to heatsink the IC package?

Click to expand...

I'd suggest a metal enclosure. You can bolt the LM317 on that for heatsinking, preferably on the opposite side of the laser as not to heat the latter up too much.

Niceee. This is very quality advice thanks again! The 317 bolting sounds very doable... I suppose that the fan would best be mounted in the rear panel, away from the LD so the ICs can be properly cooled when near the rear end of the enclosure.

So what about vents in the enclosure that the fan can push air through? Would a simple circular hole suffice? Or should i find some sort of fine grill to cover the fan to avoid dust collection? A dusty laser would be the WORST. Any particular aluminum enclosure that you guys suggest? I want the panels to be sturdy, but not something impossible to drill through. If not any one particular enclosure, is there a specific panel thickness that I should spring for?

I also had an idea... what if I used a panel mounted sliding pot to adjust the current going to the LD? This would give me control of the brightness as well as possibly lengthening the life span of the diode by being able to start up and shut off the laser with slower warm up and cool down time intervals... external control of the power level sounds pretty desirable in a Lab style laser... what do you guys think? Impractical? Unnecessary? Or something worth doing? Ooh! What about a wired remote? For power on, off, and current level adj? :

I'd suggest trying to find a cast aluminium box, some electronics stores carry them but you'll have to shop around i guess. Something like these https://www.photonage.com.au/images/images/prod/H/H0430.gif , but at a suitable size and perhaps without the mounting flanges.

As far as making holes goes: Aluminium isnt very hard and you should be able to easily drill through using any standard (hss) metal drillbit.

Making a hole for a fan could prove to be a pain though - you'd need a column drill and hole saw intended for metal (most only do plastic/wood or stone).

REMEMBER!!! The LM317 tab is positive. This means that to bolt it to a metal enclosure you'll need an isolation kit. If you buy a TO-220 heatsink kit from Radio Shack, it comes with the isolation kit. If you just bolt the tab directly to the metal enclosure, it could easily short to ground.

Ah so it sounds like drilling may not be such an issue then. I'll probably just make many 1/8" holes in some sort of a circular matrix for the fan to push the air through.

Ya I would've shorted my circuit if you hadn't have said something! Thanks!
That seems kinda goofy tho..... posistive? It shouldn't be too hard to find an insulator though you're right... The insulator is usually just some kind thin see thru plastic square isn't it? Or does it need to be something that specially conducts heat like the thermal paste that it will be covered with?

What do you guys think of the idea of external current control with a pot? I'm sure it's not original, but if I start up the LD driver with the current setting low, won't I be able to avoid the risk of those start-up voltage spikes getting to the LD? Will it in any way lengthen the life-span probability of the diode?

meatballofall said:

Ah so it sounds like drilling may not be such an issue then. I'll probably just make many 1/8" holes in some sort of a circular matrix for the fan to push the air through.

Ya I would've shorted my circuit if you hadn't have said something! Thanks!
That seems kinda goofy tho..... posistive? It shouldn't be too hard to find an insulator though you're right... The insulator is usually just some kind thin see thru plastic square isn't it? Or does it need to be something that specially conducts heat like the thermal paste that it will be covered with?

It does need to be thermally conductive (usually mica is used). Also, there is a tiny plastic sleeve that the screw goes through to ensure that it doesn't contact the LM317 tab.

What do you guys think of the idea of external current control with a pot? I'm sure it's not original, but if I start up the LD driver with the current setting low, won't I be able to avoid the risk of those start-up voltage spikes getting to the LD? Will it in any way lengthen the life-span probability of the diode?

Using an external pot would really be no different than using an internal pot. So yes, starting off low and going high will help protect your diode from spikes, but this is unnecessary since the LM317 combined with a capacitor across it's input will drop any spikes to ground. What doesn't get sent to ground will be absorbed by the LM317 itself. I recommend setting the current once and then leaving it alone.

Click to expand...

Here's my favorite LM317 circuit:



(source: Sam's Laser FAQ)

The capacitors and diodes help protect the diode from nearly all forms of voltage transients.

Hope this helps..

Interesting. I don't recognize the 10 and .1uf caps in the current regulating schematic. It shan't be hard to add those two to the parts pile! Mica... doable. Variable current control... no go. This is all definitely helping. Thanks a lot everyone!