At most cases the 'TACH' wire (usually yellow color coded) of a 3 wired fan ,will output two 12 VDC signalsI have one of the noctua flx, 140 mm nice fan well made and quiet , but I was not impressed with the cfm\static pressure. I'm thinking of running it at 15V instead of 12V.
Since then I picked up a couple of rosewill hypobera, decent pricing and check out the air pressure!
Fan Size: 140mm
http://www.amazon.com/gp/product/B006CSKM20/ref=oh_aui_detailpage_o05_s00?ie=UTF8&psc=1
- Bearing Type: HDB (Hydro Dynamic Bearing)
- RPM: 600 -1300 RPM
- Dimensions: 140 x 140 x 25mm
- Max static air pressure: 2.76 mm H2O
and oh btw do you know how to hook up an led to the tach wire so I can visually see that the fan is working ? My understanding is connect a resistor plus led from 12Vdc to the yellow tach wire But I don't know what ohm resistor and what led to use for a nice bright strobing signal.
wow SDS thats really cool,
I'm gonna put these on all my fans, so that when I peek at my grows to make sure everything is working ok I know right away that the fan is working or not.
When it comes to the fans, I like my blades simple, cheap, and ninja-like. . .At most cases the 'TACH' wire (usually yellow color coded) of a 3 wired fan ,will output two 12 VDC signals
for every rotation of the rotor.
At 1200 rounds per minute ,that translates into 2400 signals per minute .
2400 / 60 = 40 signals per second.
40 'blinks' per second ,of an indicator LED,is translated into almost continuous light ,at the vision center of a human brain.
No strobo effect here....Rather an 'dizzzing' to watch ,rapidly flickering led...
Still ,to connect directly the TACH wire with a small epoxy 20 mA led ,you will need :
12 / 0.02 = 600 Ohm .
Any resistor from 600 Ohm ,up to 1 K will do .
To make a strobo effect ,firstly you will have to select the strobo frequency ...
Say it is 20 Hz (twenty blinks per second ).
Then from Fan rpm and tach signaling (2 pulses for every round or 4 pulses per round ) ,
you will calculate the incoming signals ..|Say for example 2400 per minute .. (40 Hz )
Then you will need a simple IC (very cheap ,less than $1 ) called 4017 decade counter divider .
http://www.doctronics.co.uk/4017.htm
http://www.doctronics.co.uk/pdf_files/hcf4017.pdf
The decade counter/divider IC has 1x signal input and 10x signal outputs ...
Connect the 4017 input with the tach wire ...
Connect outputs 1,3,5,7 & 9 ,(or 2,4,6,8 & 0 ) all at the + pin of the led .(small 20 mA one ).
(reset & enable pins of the 4017 ' lowered to ground '=>connect with " - " line/wire )
At the - ( cathode ) pin of the led connect one 1K resistor .
Now for every incoming signal set of duo ,only for the one pulse the led lights up ..
Actually you 've divided the incoming signal frequency by two .
The led will blink with 20 Hz frequency .
(Perceived as 'strobing light ' .)
For a good 'flash ' choose a large RGB white one and use an 680 ohm resistor instead of 1K.
Cheers.
pretty fan!When it comes to the fans, I like my blades simple, cheap, and ninja-like. . .
View attachment 3311969
http://www.newegg.com/Product/Product.aspx?Item=N82E16835200093&cm_re=rosewill_140mm_fan-_-35-200-093-_-Product
It ran with a 5V, 1A PSU (Energizer), with a steady current of just 82mA (that's less than half a watt of juice!). I couldn't hear it make a noise other than its wobbles on the countertop.
I don't know a bunch about computer fans but when I hooked up the positive and negative wires (just two wires used from the fan), the lights and fan powered on. It appears that each LED relays back to the circuit board, where it shares power with the fan.pretty fan!
Do you know if the red leds are hooked up to the tach signal wire ?
Hmmm...
Seems Mr."Faster than light ,e fuctrion from old times " is right .....
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So ...
Be it ...
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The new -age High Intensity ....Diodes ...light ...
Still some ( booooooringgggggg ) wiring -job to be done ...
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So both scenarios have the COBs' centroids at the same distance apart but just the HS has been shortened in Tin Salmon's design? (200mm vs 160mm)200 mm length
160 mm Length (-20 mm per side ),as Salmonetin suggested..
View attachment 3312447
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View attachment 3312449
Tj : 70.6 vs 74.3 ...
Tcase : 55.2 vs 58.3
|Pressure drop : 17.346 vs 17.2 Pascal ..
Cutting off 20 mm of heatsink per side only attributes to a lower pressure drop
of ~ 0.146 Pa ..
Final result though,is that Tcase rises 3.1 C as Tj rises 3.7 C.
Cheers.
Yes ...So both scenarios have the COBs' centroids at the same distance apart but just the HS has been shortened in Tin Salmon's design? (200mm vs 160mm)
Your the best SDS!!
I tried out the R-Tools program - it was great!200 mm length
160 mm Length (-20 mm per side ),as Salmonetin suggested..
View attachment 3312447
View attachment 3312448
View attachment 3312449
Tj : 70.6 vs 74.3 ...
Tcase : 55.2 vs 58.3
|Pressure drop : 17.346 vs 17.2 Pascal ..
Cutting off 20 mm of heatsink per side only attributes to a lower pressure drop
of ~ 0.146 Pa ..
Final result though,is that Tcase rises 3.1 C as Tj rises 3.7 C.
Cheers.
Equates that something's wrong ...I tried out the R-Tools program - it was great!
The biggest obstacle for me was the flow conditions. They give the user 3x options of route and each one is unique. I kept getting high numbers for pressure drop, like ~80 Pa. I'm not entirely sure what that equates to in this situation. Is that due to the fans sucking and blowing air and the air becoming hotter after be thrown in and out of the HS?
Two fans ...Also, if I have 2x fans and added together they make ~100CFM, would I use that as the flow rate? It seemed like when I solved for the flow velocity (RPM x radius of fan), the temperatures across the HS were unbelievably low (like 26C highs).
The total area of the thermal transferring surface ..One more thing I would like to ask: do you use the diameter of the light-emitting surface as your object or do you use the entire COB, ceramic and all?
The thing about spacing multiple light sources on 1 heat sink is that you're optimizing for 2 things.
1) Cooling effectiveness
2) Good light distribution.
Often that means sacrificing a bit of 1 to get more of the other. If you optimize only for cooling factors like even heat sink temperature, you lose flexibility on how you position the lights. Similarly, if you optimize for optimal light distribution, you will sacrifice optimal thermal properties. It's hard to know exactly where the balance is.
If given a choice between slightly better thermal properties or slightly better light distribution, I'd choose the light distribution. That doesn't mean putting them on the outer edges of the longest span of the sink, but somewhat farther apart than perfect cooling.