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Slowing down a box fan
NMB min boxer
Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? |
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#2
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In article , ren wrote:
NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? You can use a three pin 5V regulator that comes in a TO-220 case. They're a dime a dozen and easy to find. Connect +12V to pin IN. Run a 220 Ohm resistor from pin OUT to pin GND. Put a 330 Ohm potentiometer between pin GND and the negative power. Put the fan on pin OUT and the negative power. That will let you adjust from 5V to full voltage. (A 12V brushless fan usually stalls around 4V) 3-pin 5v Regulator +12V ----- IN OUT ---+------ + Fan GND | | 220 Ohm | | +--------+ | Pot | 0V --------------------+------ - Fan Another option is to use a 12V thermal sensing exhaust fan. Pick a fan with the temperature you desire and it only spins as fast as it needs to. They're common at computer parts stores. |
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#3
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Kevin McMurtrie wrote in
: In article , ren wrote: NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? You can use a three pin 5V regulator that comes in a TO-220 case. They're a dime a dozen and easy to find. Connect +12V to pin IN. Run a 220 Ohm resistor from pin OUT to pin GND. Put a 330 Ohm potentiometer between pin GND and the negative power. Put the fan on pin OUT and the negative power. That will let you adjust from 5V to full voltage. (A 12V brushless fan usually stalls around 4V) 3-pin 5v Regulator +12V ----- IN OUT ---+------ + Fan GND | | 220 Ohm | | +--------+ | Pot | 0V --------------------+------ - Fan Another option is to use a 12V thermal sensing exhaust fan. Pick a fan with the temperature you desire and it only spins as fast as it needs to. They're common at computer parts stores. Overkill. A 33 ohm 2W resistor will do the job nicely. |
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#4
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On Sun, 03 Apr 2005 14:43:03 -0500, Jimbo
wrote: Another option is to use a 12V thermal sensing exhaust fan. Pick a fan with the temperature you desire and it only spins as fast as it needs to. They're common at computer parts stores. Overkill. A 33 ohm 2W resistor will do the job nicely. Better yet, a zener diode. You could buy a couple different voltages to experiment with. |
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#5
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"ren" wrote in message
NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? An off-the-shelf device: http://www.jab-tech.com/customer/pro...artner=froogle |
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#6
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"Arny Krueger" wrote in
: "ren" wrote in message NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? An off-the-shelf device: http://www.jab-tech.com/customer/pro...82&partner=fro ogle Costs 10 times as much as a resistor. |
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#7
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In article ,
Jimbo wrote: Kevin McMurtrie wrote in : In article , ren wrote: NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? You can use a three pin 5V regulator that comes in a TO-220 case. They're a dime a dozen and easy to find. Connect +12V to pin IN. Run a 220 Ohm resistor from pin OUT to pin GND. Put a 330 Ohm potentiometer between pin GND and the negative power. Put the fan on pin OUT and the negative power. That will let you adjust from 5V to full voltage. (A 12V brushless fan usually stalls around 4V) 3-pin 5v Regulator +12V ----- IN OUT ---+------ + Fan GND | | 220 Ohm | | +--------+ | Pot | 0V --------------------+------ - Fan Another option is to use a 12V thermal sensing exhaust fan. Pick a fan with the temperature you desire and it only spins as fast as it needs to. They're common at computer parts stores. Overkill. A 33 ohm 2W resistor will do the job nicely. Some brushless fans will not reliably start with a series resistor of high enough value to slow them down. A series 47 Ohm wirewound pot and a series 1000 microfarad capacitor would more reliably start up. 1000µF 16V +----|(----+ | | ----+--- 47 ---+---- Ohm pot I think a 3-pin regulator and a 330 Ohm pot is cheaper. Electronics surplus stores have them for 20 to 80 cents each. |
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#8
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"Jimbo" wrote in message
"Arny Krueger" wrote in : "ren" wrote in message NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? An off-the-shelf device: http://www.jab-tech.com/customer/pro...82&partner=fro ogle Costs 10 times as much as a resistor. Depends on the resistor. For opener's the product I mentioned above is variable. The product also provides a low source impedance to the fan motor, which tends to reduce stalling and cogging. |
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#9
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On Mon, 4 Apr 2005 04:22:49 -0400, "Arny Krueger"
wrote: "Jimbo" wrote in message "Arny Krueger" wrote in : "ren" wrote in message NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? An off-the-shelf device: http://www.jab-tech.com/customer/pro...82&partner=fro ogle Costs 10 times as much as a resistor. Which is still insignificant compared to what the fan is likely cooling. Depends on the resistor. For opener's the product I mentioned above is variable. The product also provides a low source impedance to the fan motor, which tends to reduce stalling and cogging. I'd want such a device to be able to detect the varying current of a running fan (I've not tested this but I presume these small fan motors pull varying pulses of current as different coils are switched), and if it's NOT varying then it's NOT running, and it should put more voltage/current into it until it DOES start running. This could be done with a little circuitry, perhaps even using a cheap 8-bit microcontroller, which could detect the rotational speed from the current pulses pulled, and run the fan at any desired RPM up to it's max. Even a series diode or pot and emitter-follower transistor circuit (providing a voltage that does not significantly drop with increased load) would be better than a resistor which may not put enough voltage to start up the fan if it gets loaded with dust. ----- http://mindspring.com/~benbradley |
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#10
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Ben Bradley wrote:
I'd want such a device to be able to detect the varying current of a running fan (I've not tested this but I presume these small fan motors pull varying pulses of current as different coils are switched), and if it's NOT varying then it's NOT running, and it should put more voltage/current into it until it DOES start running. Many PC cooling fans have built-in tachometer. Circuitry on the system board that monitors rpms, detects stalled fans, etc; provides interface to software running on the PC. |
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#11
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On Sat, 02 Apr 2005 16:46:16 -0500, ren wrote:
NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? Another way is to connect the black lead to +5 instead of 0v. That puts 7v across the fan (leave the red lead on +12v!), which is usually enough to let it start reliably yet still run quietly. I ran the PSU fan like this on a 486 operating as a router for a couple of years without problems. I wouldn't recommend delving inside the psu though... ;-) -- Mick (no M$ software on here... :-) ) Web: http://www.nascom.info Web: http://projectedsound.tk |
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#12
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ren wrote:
NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? Anyone have any pointers on where I can tap 5 or 12 volts DC without introducing hum into the output signal: http://www.freeinfosociety.com/elect...aliberplus.pdf Or explain why the footswitch power supply upgrade is listed on page three. |
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#13
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ren wrote:
NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? Try a 12-16 volt light bulb in series with the fan. I've done this quite a few times with the desired results. The problem with just regulating the 12 volts down to 5 or so is the fan may not start every time. A light bulb has a low resistance when cold (off) and will allow almost a full 12 volt drop across the fan motor when it starts. As the fan speeds up the bulb is also warming up and increasing resistance, dropping the voltage across the fan and slowing the fan. You may have to try a couple different bulbs until you find one that goes well with the fan, but always use a bulb with a higher voltage rating than your supply voltage so it doesn't burn out. I have a few of these in use, some have been going almost twenty years without having to change the bulb. -W8LNA -- Galen Watts RF Engineer National Radio Astronomy Observatory PO Box 2 (or) Route 28/92 Green Bank, West Virginia 24944-0002 http://www.gb.nrao.edu/ 304-456-2134 304-456-2200 fax |
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#14
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On Mon, 04 Apr 2005 17:52:34 GMT, Ben Bradley
wrote: The product also provides a low source impedance to the fan motor, which tends to reduce stalling and cogging. I'd want such a device to be able to detect the varying current of a running fan (I've not tested this but I presume these small fan motors pull varying pulses of current as different coils are switched), and if it's NOT varying then it's NOT running, and it should put more voltage/current into it until it DOES start running. This could be done with a little circuitry, perhaps even using a cheap 8-bit microcontroller, which could detect the rotational speed from the current pulses pulled, and run the fan at any desired RPM up to it's max. Even a series diode or pot and emitter-follower transistor circuit (providing a voltage that does not significantly drop with increased load) would be better than a resistor which may not put enough voltage to start up the fan if it gets loaded with dust. That can be solved by putting a fairly large bypass capacitor in parallel with the resistor. the fan will receive a large starting slug of current and when the capacitor charge equallizes, the resistor will take over. Regards, Bruce Hitting reply is futile, use the following: ). |
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#16
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Jimbo wrote:
Kevin McMurtrie wrote in : In article , ren wrote: NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? You can use a three pin 5V regulator that comes in a TO-220 case. They're a dime a dozen and easy to find. Connect +12V to pin IN. Run a 220 Ohm resistor from pin OUT to pin GND. Put a 330 Ohm potentiometer between pin GND and the negative power. Put the fan on pin OUT and the negative power. That will let you adjust from 5V to full voltage. (A 12V brushless fan usually stalls around 4V) 3-pin 5v Regulator +12V ----- IN OUT ---+------ + Fan GND | | 220 Ohm | | +--------+ | Pot | 0V --------------------+------ - Fan Another option is to use a 12V thermal sensing exhaust fan. Pick a fan with the temperature you desire and it only spins as fast as it needs to. They're common at computer parts stores. Overkill. A 33 ohm 2W resistor will do the job nicely. I think you will find that the fan desires about 66% of it's rated voltage to start and about 33% to continue to run once started. You would do better to put a thermal sensor in series with it so it only runs when needed. |
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#17
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ren wrote: NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? Since your already mousing it with a wall wart, why not just try a 9 volt and 6 volt wall wart and see what happens? At one time, rat shack sold one that had a variable output voltage switch on it. Bob ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
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#18
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On Wed, 06 Apr 2005 19:16:18 -0500, Bob Urz wrote:
ren wrote: NMB min boxer Model 3610NL-04W-B10 12 VDC 0.13 AMPERES I have a wall wart Output 12VDC 200mA The fan makes too much noise and pushes much more air than I need. If I can slow the fan down to make it quieter it will still push enough air for me. How can I accomplish this? Power resistors? Since your already mousing it with a wall wart, why not just try a 9 volt and 6 volt wall wart and see what happens? At one time, rat shack sold one that had a variable output voltage switch on it. Or just stick a 70ohm resistor in series. A lot cheaper than another wallwart. |
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#19
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On Wed, 06 Apr 2005 04:18:50 GMT, "wß" wrote:
I think you will find that the fan desires about 66% of it's rated voltage to start and about 33% to continue to run once started. You would do better to put a thermal sensor in series with it so it only runs when needed. It needs current to run, actually, which is why the zener diode method works better than a resistor - the zener will not restrict current to the motor, like a resistor will. |
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#20
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On Thu, 07 Apr 2005 02:21:34 GMT, dizzy wrote:
On Wed, 06 Apr 2005 04:18:50 GMT, "wß" wrote: I think you will find that the fan desires about 66% of it's rated voltage to start and about 33% to continue to run once started. You would do better to put a thermal sensor in series with it so it only runs when needed. It needs current to run, actually, which is why the zener diode method works better than a resistor - the zener will not restrict current to the motor, like a resistor will. Yes it will. It'll reduce the voltage at the motor, reducing the current. |
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#21
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Grab a bunch of 1N4001 (or '02 or '04 etc) diodes from Radio Shack.
They're dirt cheap. Put them in series to reduce the voltage and slow the fan. Each diode will drop around 600mV. Unlike a resistor they won't interfere with starting current OR the commutation transients. Like someone posted zeners can work as well and can use fewer parts if you're dropping a larger voltage (say 5V). However, putting all the power dissipation in one zener may be too much power for the zener. As for sensing failure either get a fan with a tachometer output or one with a stall indicator. Both use the third wire. Connect a resistor (10k or so) from the third wire to +5V or +12V. You'll get two pulses per revolution for the tach output or a steady voltage for the stall indicator. |
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#22
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On Wed, 06 Apr 2005 23:09:53 -0500, TCS
wrote: On Thu, 07 Apr 2005 02:21:34 GMT, dizzy wrote: On Wed, 06 Apr 2005 04:18:50 GMT, "wß" wrote: I think you will find that the fan desires about 66% of it's rated voltage to start and about 33% to continue to run once started. You would do better to put a thermal sensor in series with it so it only runs when needed. It needs current to run, actually, which is why the zener diode method works better than a resistor - the zener will not restrict current to the motor, like a resistor will. Yes it will. No, it will not, "like a resistor will". It'll reduce the voltage at the motor, reducing the current. Yes, it reduces voltage at the motor, that's what it would be there for. But, compared to a resistor, a diode adds very little source impedance, so it will NOT limit the available startup current like a resistor will. |
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#23
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dizzy is correct.
A resistor can work but a zener (or the series string of diodes I suggested) is a better solution. One of the fans I have draws a nominal 230mA at 12V. Peak starting current varies but I have measured over 2A. Each commutation spike is over 1A. With this fan a 24.9 ohm resistor drops the running voltage to about 6V. However, the fan will only start about 25% of the time. You can kick start the fan by spinning it with you finger and it will start running. It also has the problem of once running if the load increases (back pressure or a finger to slow the blades down) the fan will stall and may or may not restart. It can be bad enough that if you put your hand over the intake (not actually touching the fan) it will stall and not restart. A 100uF capacitor across the fan can help prevent stalling during running. However, it decreases the chances of starting since the capacitor charging current robs the fan of badly needed startup current. In the absence of a stiff regulated voltage source a diode (zener or series string) is the more reliable solution. |
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#24
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On 11 Apr 2005 18:38:01 -0700, "Rusty B." wrote:
dizzy is correct. A resistor can work but a zener (or the series string of diodes I suggested) is a better solution. One of the fans I have draws a nominal 230mA at 12V. Peak starting current varies but I have measured over 2A. Each commutation spike is over 1A. With this fan a 24.9 ohm resistor drops the running voltage to about 6V. However, the fan will only start about 25% of the time. You can kick start the fan by spinning it with you finger and it will start running. It also has the problem of once running if the load increases (back pressure or a finger to slow the blades down) the fan will stall and may or may not restart. It can be bad enough that if you put your hand over the intake (not actually touching the fan) it will stall and not restart. A 100uF capacitor across the fan can help prevent stalling during running. However, it decreases the chances of starting since the capacitor charging current robs the fan of badly needed startup current. That's why the capacitor is in shunt with the resistor, not across the fan. Regards, Bruce Hitting reply is futile, use the following: ). |
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#26
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"Rusty B." wrote in message
oups.com... dizzy is correct. (snip) ... It also has the problem of once running if the load increases (back pressure or a finger to slow the blades down) the fan will stall and may or may not restart. It can be bad enough that if you put your hand over the intake (not actually touching the fan) it will stall and not restart. If you block the air flow to a fan it does less work and so pulls less power, not more, so it speeds up. Try it with a canister vacuum cleaner - block the tube and listen. Cheers, Roger |
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#27
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On Fri, 15 Apr 2005 18:36:18 -0400, Engineer wrote:
"Rusty B." wrote in message roups.com... dizzy is correct. (snip) ... It also has the problem of once running if the load increases (back pressure or a finger to slow the blades down) the fan will stall and may or may not restart. It can be bad enough that if you put your hand over the intake (not actually touching the fan) it will stall and not restart. If you block the air flow to a fan it does less work and so pulls less power, not more, so it speeds up. Try it with a canister vacuum cleaner - block the tube and listen. I'll keep that in mind next time I have a canister vacuum cleaner that runs off a DC box fan. |
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#28
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Note I did not say "work". I said load.
Technically, you are correct. Work by definition requires displacement. Pick up a heavy monoblock amplifier and hold it above your head. Work is done hefting it above your head but no work is done just holding there. So blocking the air flow does reduce the work being done in the technical sense. However, the force exerted by the motor changes depending upon impeller design. The blades in your vacuum obviously stall which reduces the load. For the DC brushless fans we're talking about the load increases. Try two things: 1. Measure the current drawn by the fan in free air and with the intake blocked. Which one draws more current and thus power? 2. Put a resistor in series with the fan. Size the resistor so the fan almost stalls. Block the intake and watch the fan stop. |
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