Foxes, see canines.
Scrat appears to be a squirrel, fox, and wolf all in one with t-rex short arms and fangs.
Macintosh SE or SE/30 Fan Bracket
- Thread starter alxlab
- Start date
Scrat appears to be a squirrel, fox, and wolf all in one with t-rex short arms and fangs.
Are you in the U.S. or elsewhere? Very curious about cost of fan and locally printed ductwork? Thinking of running the test regime with my pass-thu fan/horizontal neck board SE.
Stock 1987 SE tested in four configurations:
- OEM pass-thru fan setup
- swapped in SE/30 axial fan/sheet metal ducting bodge.
- @alxlab 1.0 design conical printed ducting
- 1.1 version adapted register boot config ducting
Might add Noctua variants of last three, but PITA reduces the possibility of even starting with this.
Casually noodling out a CFM exhaust output test rig. Can't imagine something tinkered together to give proper output in CFM. Thinking in terms of an ultralight, undershot waterwheel form factor with teensy DC motor generation for comparative voltmeter readings? Methinks that would suffice?
Suggestions for another such TinkerToy?
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An automotive mass air flow sensor does exactly this.
Or you could see how long it takes to fill a trash bag.
The third wire on a fan is typically a tach output.
The MAF sensor is for measuring CFM in a test bench setup, not something you'd permanently install in the Mac.
MAF sensor output is typically a voltage or a frequency output.
Thanks! I figured the concept was viable. Looked at MAF on Wikipedia and found a far more simple mechanism than the undershot water wheel model for a flow sensor mechanism. VAF (volume air flow) sensor:
Mass flow sensor - Wikipedia
LOL! Too many variables. That's an application of the KISS at its very worst!
@retr01 enough with the animation silliness already, that joke has run its course I think?
On the VAF...
Engines generate orders of magnitude greater (negative) pressure than computer fans, so I don't think a VAF will provide an accurate measurement, if any.
Hot wire MAFs are more suited to measuring the lower static pressures of fans, without moving parts.
Engines generate orders of magnitude greater (negative) pressure than computer fans, so I don't think a VAF will provide an accurate measurement, if any.
Hot wire MAFs are more suited to measuring the lower static pressures of fans, without moving parts.
Thanks, sounds good, but didn't see the operational method offhand. The heating of the wire for measuring cooling effects of airflow seems problematic in terms of implementation without variance between setups.
I'll have to play some with the images floating around in my head, do some sketches and get something down in AI.
Was thinking vertical format for the "flapper" in a straight vs. L shaped conformation in the article's illustration. Given ultralight construction, airflow shouldn't be restricted much at all I think.
Counterweight for vertical vane/flapper would be minimal, consisting of a needle with angular deflection readings taken visually against a protractor. Integrated gunsite distanced from needle/scale would keep readings consistent well enough I think?
I'll have to play with the images in my head, do some sketches and get something down in AI. Was thinking vertical format, straight instead of L shaped with ultralight construction. Counterweight would be minimal, consisting of a needle with gun site readings from side on a protractor.
Dunno, but vane/needle bodge, housing and protractor scale development will be a lot of fun! Thoughts of floating dope on water to make form thin film on a balsa wood frame again brings back wonderful memories!
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It's a tach output attached to a hall effect sensor, it has no control influence. You'd need a 4-wire fan to get the low voltage PWM speed control. Or you could add a mosfet inline with the input power to turn it off and on. Probably not worth it when you can just get a Noctua that has enough air flow and is still silent at full speed.Let's throw "typical" out. Can a sensor control RPM via the third wire, since the third wire is tach?
That's very interesting! I just checked my SE analog board and it has the through holes for the fan power like yours. I wonder if all the analog boards have the solder points even if they use wires.
First time poster here - hello all!
When the SCSI hard drive died in my SE/30 and I replaced it with a BlueSCSI, I noticed the fan noise now seemed very loud, even after changing its stock Elina to a Noctua NFA6x25 fan. I wanted the computer to be much quieter...
This drove me to design a microcontroller-powered circuit, which is able to measure internal case temperature from a digital temperature sensor chip (accuracy ±1°C), also on the board, to then control the speed of a PWM fan. This basically allows lower and much quieter fan speeds when the computer isn't that hot inside. It works by ramping up and down the fan speed, the minimum at 22°C, and full speed at 40°C. Below 22°C the fan doesn't need to be on at all, though it always turns on briefly when the Mac is powered up to confirm the fan is functioning.
The microcontroller generates a 25kHz 5-volt PWM signal in accordance with the "Noctua PWM Specifications White Paper", which will be compatible with all standard PWM fans.
I've tested the circuit for about 30 hours in varying conditions. When installed in my SE/30 ,generally, for the first 15-20 minutes after powering up, the Mac is basically silent. The fan gradually steps up in speed as the internals warm up, but even running intensive testing programs in a warm room for several hours doesn't cause the temperature to climb that high, and so it's considerably quieter than if I had just attached a Noctua to 12V and left it on full speed.
I'm really pleased with how well this controller design works, the computer is now as quiet as sensibly possible and with no modifications to the Mac itself.
Here are a couple of pictures of my homebrew prototype and where it is currently located inside the Mac for testing. The final design will be far smaller than my prototype board. It has two connectors: a standard molex plug for 12V power, and a 4-pin header to connect the fan.
I'm in the process of finalising a production PCB design and designing a 3D fan housing model (similar to the one in this post) which would be able to hold the circuit board securely, I think the best place to locate the board (and therefore sensor) would be horizontally just above the fan, near the flyback cage, and in the 'dead' air space just below the top of the case, where the internal temps are likely to be highest.
I've also designed a test circuit and written a separate program for testing, which I'm in the process of wiring up to the Mac's serial port, so I can gather and save data to plot internal temp / fan PWM / fan RPM over time, which may be interesting for the community. Just need to wire it all up and spend some time capturing and plotting the data... I also plan to make some recordings, to compare the sound levels from stock fan / Noctua at full speed, and what the fan sounds like at different temperatures.
I'm thinking of making a small run of these boards and could make them available for a reasonable cost (£15 or less, depending on number).
Do message me if you're interested so I can gauge whether to order some parts for more than just me! Be aware though that this design requires a 4-pin PWM fan rather than the 3-pin style (which will always run at full speed if connected to the Mac's 12V supply).
Will post updates with more data in a couple of weeks.
Ross
When the SCSI hard drive died in my SE/30 and I replaced it with a BlueSCSI, I noticed the fan noise now seemed very loud, even after changing its stock Elina to a Noctua NFA6x25 fan. I wanted the computer to be much quieter...
This drove me to design a microcontroller-powered circuit, which is able to measure internal case temperature from a digital temperature sensor chip (accuracy ±1°C), also on the board, to then control the speed of a PWM fan. This basically allows lower and much quieter fan speeds when the computer isn't that hot inside. It works by ramping up and down the fan speed, the minimum at 22°C, and full speed at 40°C. Below 22°C the fan doesn't need to be on at all, though it always turns on briefly when the Mac is powered up to confirm the fan is functioning.
The microcontroller generates a 25kHz 5-volt PWM signal in accordance with the "Noctua PWM Specifications White Paper", which will be compatible with all standard PWM fans.
I've tested the circuit for about 30 hours in varying conditions. When installed in my SE/30 ,generally, for the first 15-20 minutes after powering up, the Mac is basically silent. The fan gradually steps up in speed as the internals warm up, but even running intensive testing programs in a warm room for several hours doesn't cause the temperature to climb that high, and so it's considerably quieter than if I had just attached a Noctua to 12V and left it on full speed.
I'm really pleased with how well this controller design works, the computer is now as quiet as sensibly possible and with no modifications to the Mac itself.
Here are a couple of pictures of my homebrew prototype and where it is currently located inside the Mac for testing. The final design will be far smaller than my prototype board. It has two connectors: a standard molex plug for 12V power, and a 4-pin header to connect the fan.
I'm in the process of finalising a production PCB design and designing a 3D fan housing model (similar to the one in this post) which would be able to hold the circuit board securely, I think the best place to locate the board (and therefore sensor) would be horizontally just above the fan, near the flyback cage, and in the 'dead' air space just below the top of the case, where the internal temps are likely to be highest.
I've also designed a test circuit and written a separate program for testing, which I'm in the process of wiring up to the Mac's serial port, so I can gather and save data to plot internal temp / fan PWM / fan RPM over time, which may be interesting for the community. Just need to wire it all up and spend some time capturing and plotting the data... I also plan to make some recordings, to compare the sound levels from stock fan / Noctua at full speed, and what the fan sounds like at different temperatures.
I'm thinking of making a small run of these boards and could make them available for a reasonable cost (£15 or less, depending on number).
Do message me if you're interested so I can gauge whether to order some parts for more than just me! Be aware though that this design requires a 4-pin PWM fan rather than the 3-pin style (which will always run at full speed if connected to the Mac's 12V supply).
Will post updates with more data in a couple of weeks.
Ross