Passive Heatsinking Only - Comments

[FourDee]

It's a screendump from the TC621 datasheet...


I'm currently working on some PCB-designs for the laserprojectors we're building here (connector-PCB's with Ethercon for ILDA in/out and on the inside PCB-headerconnectors for connection to the lasers/scanners/etc). The only problem is that a day only has 24 hours...

That's exactly what I'm using for my projector (ethercon) and powercon ofcourse

[JeroenVDV]

That's exactly what I'm using for my projector (ethercon) and powercon ofcourse

No Powercon here for the new projectors

Euro-connectors are the way to go (cheap, simple to use, everybody has Euro-cables enough in case you forget something).

[FourDee]

Everywhere I go, there seem to be plenty of powercon cables, so no prob there

[White-Light]

Jem I'm throwing this thread back up because having been directed here from another post, I think I know of something that might help you get good cooling but quietly.

Take a look at these pc coolers:

http://www.dvhardware.net/review106_noctua_fans.html

8cm Version (Page 1 of review):

L.N.A. = Low Noise Adapter (U=ultra)

Without adapter: Airflow: 53m³/h (31.2CFM) Noise: 17dBA

With L.N.A.: Airflow: 39m³/h (23CFM) Noise: 10dBA

With U.L.N.A. Airflow: 26m³/h (15.3CFM) Noise: 7dBA

12 cm Version (Page 2 of review) - Where the real action is at!!!

Without adaptor: Airflow: 81m³/h (47.7CFM) Noise: 17dBA

With U.L.N.A. adaptor: Airflow: 41m³/h (24.1CFM) Noise: less than 6dBA

The 12cm versions cost between £9-12 depending on where you shop.

Not sure on the 8cm version. However, if you can fit 12's then consider it. The general rule is the larger the fan and the slower it turns, the quieter the fan for any given airflow.

[platinum]

Take a look at these pc coolers:

http://www.dvhardware.net/review106_noctua_fans.html

Those are the ugliest fans I've seen in quite some time, but they seem pretty awesome otherwise. I'm tempted to put those in my bedroom computer.

-Jonathan

[White-Light]

I don't think they'e going to win any beauty contests, but if you want a quiet pc (or laser) they're about as good as you can get.

BTW beware some cheap brands making low noise claims, some simply can't reproduce the figures claimed.

[tocket]

I actually have a Noctua NF-S12-1200 in my projector (video). It's a very nice fan. I run it at full speed as the 400W HID lamp generates a fair amount of heat, but it's still rather quiet. It makes about as much noise as the ballast/lamp.

One thing to keep in mind with these quiet fans though is that they have significantly reduced performance over pressure gradients. This means that you'll get far less airflow blowing air in or out of a box as that creates over/under-pressure.

Wasn't the topic passive cooling though?

It's amazing what a bit of forced convection does for heat transfer.

[danielbriggs]

Apologies for dragging this back up.
I just thought I'd post my findings.

I'd been looking for a decent design for a fan controller for my projector in the pipeline, and most of the off the shelf controllers didn't do what I wanted i.e. they ran the fans at 40%-100% or something, also the price is bloody expensive for some of the PC marketed controllers. Besides, where is fun if every component is an 'off the shelf' job?!

I needed a controller which could: power 4x 120mm fans, run them from zero to full on (and everything in between), small and compact, and have adjustable limits for when the fans kick in.

So after a bit of digging I found this:
http://www.cpemma.co.uk/thermal.html
The PWM circuit fits the bill perfectly, so I'm going to build on in the future when my case is sorted.

He mentions the "bells and whistles" version at the bottom, as well as the basic circuit. I like the full version, as it gives the fans a kick start, so they don't stall when first powered, amongst other things. (except the diode clamp add-on - forget that)

Basically, I'm aiming for 4x 120mm fans which will sit on two opposite sides of the case (with air filters) and only power up when things get toasty. When it's cold, they do bugger all. Job done

There is one thing, where would the best place for the thermistor be? I could just have it monitoring the ambient case temp. but would it be suited say near the galvo mounting block or perhaps the PSU?

Ta,
Dan

[FourDee]

I personally think that is WAY overkill.
Why not use a pid controller to control your fans

Your electronics do not need to be climatised do they? You just want them to run cool enough

[buffo]

If you are going to have 4 120mm fans, you *will* want some way to turn them off, or at least slow them down. Otherwise you might over-cool the insides of the projector (if you are running it outside, for example), and cold temps are bad for the stability (and power output) of a DPSS blue laser.

I agree that the controller seems to be a bit much, but if you build it yourself it won't be very expensive. Personally, I think I'd just go with a pair of 120mm fans though.

Adam