Upgraded my Kenometer lite with a cooling fan

[dieselmarine]

I noticed if I keep my meter on for a little while it got slightly hot. So, I decided to put in a cooling fan. I drilled holes in the bottom of the meter, so the hot air is pushed out by the fan. Also, I added larger feet to elevate the meter for better air flow.
-Sarge

 

[Kenom]

airflow is not a bad idea, however you need to completely isolate the pile inside that case from the airflow. It will allow the sensor to cool with the beam shining on the sensor and skew your readings. Just a plastic wall or something to keep the air around the pile from moving.

 

[dieselmarine]

Thanks Ken but I'm way ahead of you lol , I isolated the the pile with some R-19 so that everything but the pile is cooled by the air flow.
-Sarge

 

[lasersbee]

I'm not catching your drift DM...:undecided:

I'd be interested to see the inside look of your
Thermopile Sensor and Fan setup...

Jerry

 

[laser_freak]

In general airflow near a thermopile is a bad idea, but it sounds like you've insulated it from the fan. I'd also be interested in some pictures of the inside.

 

[dieselmarine]

Here are those pics you guys asked for, I insulated the pile with R-19 insulation, Then I isolated the pile from the rest of the components with some more R-19 so that it does not recieve any air flow just the electrical components are cooled! I hope this helped you understand my logic a little bit better.

-Sarge

 

[lasersbee]

Here are those pics you guys asked for, I insulated the pile with R-19 insulation, Then I isolated the pile from the rest of the components with some more R-19 so that it does not recieve any air flow just the electrical components are cooled! I hope this helped you understand my logic a little bit better.

-Sarge

Hey DM.... you got a small problem....:cryyy:

Speaking only for accuracy's sake....................

The principle of a Thermal head is to have a non heat dissipating
surface (where the laser hits) on one side of the Thermocouple
circuit and a Large Thermal Mass (the large Black aluminum Block)
to dissipate (into the surrounding ambient air) any heat transferred
to it by conduction from the Active Area of the Thermopile sensor.

By insulating and putting your Thermopile in a Box you are defeating
the heat transfer/dissipation design of the Thermopile... IMO

Since your Head is insulated...if you are taking multiple readings of..
let's say... 1 Watt Lasers... the Heat absorbed by the Sensor and
conducted to the Thermal Mass will not get dissipated to the
surrounding air and will heat up the mass more and more...

It is the difference of temperature of the Active Area and the Thermal
Mass that translates to an accurate Power Reading.... and that is the
way the head was originally calibrated by OPHIR...

[EDIT]
BTW.... All of the Lite's electronics and head combined only draw about
70mA.... Where is the heat coming from that you need a fan to keep
it cool....:thinking:

My Lite runs off a 9Volt rechargeable Battery...


Jerry

 

[laser_freak]

Hey DM.... you got a small problem....:cryyy:

Speaking only for accuracy's sake....................

The principle of a Thermal head is to have a non heat dissipating
surface (where the laser hits) on one side of the Thermocouple
circuit and a Large Thermal Mass (the large Black aluminum Block)
to dissipate (into the surrounding ambient air) any heat transferred
to it by conduction from the Active Area of the Thermopile sensor.

By insulating and putting your Thermopile in a Box you are defeating
the heat transfer/dissipation design of the Thermopile... IMO

Since your Head is insulated...if you are taking multiple readings of..
let's say... 1 Watt Lasers... the Heat absorbed by the Sensor and
conducted to the Thermal Mass will not get dissipated to the
surrounding air and will heat up the mass more and more...

It is the difference of temperature of the Active Area and the Thermal
Mass that translates to a Power Reading....


Jerry

I agree. Insulation around the thermopile is bad. Having it in the project box with the rest of the electronics is already bad enough. Ideally the thermopile should be naked with nothing surrounding it. IMO the insulation is worse than the fan.

 

[dieselmarine]

Hey DM.... you got a small problem....:cryyy:

Speaking only for accuracy's sake....................

The principle of a Thermal head is to have a non heat dissipating
surface (where the laser hits) on one side of the Thermocouple
circuit and a Large Thermal Mass (the large Black aluminum Block)
to dissipate (into the surrounding ambient air) any heat transferred
to it by conduction from the Active Area of the Thermopile sensor.

By insulating and putting your Thermopile in a Box you are defeating
the heat transfer/dissipation design of the Thermopile... IMO

Since your Head is insulated...if you are taking multiple readings of..
let's say... 1 Watt Lasers... the Heat absorbed by the Sensor and
conducted to the Thermal Mass will not get dissipated to the
surrounding air and will heat up the mass more and more...

It is the difference of temperature of the Active Area and the Thermal
Mass that translates to an accurate Power Reading.... and that is the
way the head was originally calibrated by OPHIR...

[EDIT]
BTW.... All of the Lite's electronics and head combined only draw about
70mA.... Where is the heat coming from that you need a fan to keep
it cool....:thinking:

My Lite runs off a 9Volt rechargeable Battery...


Jerry

I did'nt think about that, but you make perfect sense. What I will do now is get a new smaller project box that I will house all of the electrical components in and cool them with the fan, for the pile i'll either mount it on top of the box or use a tripod. Thank you Jerry for all your advice and wisdom!

I am using a 12v power supply could that be the heat issue?

-Sarge

 

[lasersbee]

N/P.... the best is always on the outside... all our original
Kenometers with the Heads in the box next to the very
hot PS were modified by us and placed outside.

I still can't see why you even need a fan... 70mA is not
enough to heat any of the components in the Lite...

Have you tested how much current YOUR Lite is actually
drawing from your PS... If it is Pulling over 100mA there
may be another problem...


Jerry

 

[dieselmarine]

Ok I fix the issue, The pile is on the outside of the enclosure and the meter zero's it self out alot better now it idles at 0000 -0001-0002 instead od 0007 or 8 like it use to. I am running it off a 9v lithium and I used a heat sink for the voltage regulator. Its not heating up anymore, Its easier to get a reading with the pile on the outside. My dilda with a rkcstr driver set @ 440mA, Loc diode, aixiz red glass lense, 2x 3.7v cr2 juice cells shes pushing 300mW Schweet!
Thanks for all the help with my Kenometer guys!
-Sarge