PWM-->Analog Fan controller for conventional 3-pin fans
Moderators: NeilBlanchard, Ralf Hutter, sthayashi, Lawrence Lee
PWM-->Analog Fan controller for conventional 3-pin fans
I have created a custom circuit similar in spirit to the one created by DirtyLude/Mark Higgins. But, I think we are each targeting different use cases. In my case, I'm depending on modern motherboards which already have PWM drivers built-in. My circuit takes a PWM input signal, and creates a steady variable output voltage. It was originally designed for a water pump, but it can power any two devices with normal 3-pin fan connectors on them. Mark's circuit does just the opposite. PWM is not present in the system, and pulsed power is generated by the circuit.
The other difference is that my circuit makes no attempts to interpret temperatures. CPU, GPUs, and motherboards already contain temperature monitoring embedded in the chips themselves. So, you can use SpeedFan or your motherboard's BIOS to interpret temperature levels, and adjust the PWM signal to your fan headers. The circuit simply turns PWM into a steady variable voltage.
The total size of the circuit is 1"x1.5". I have ordered the PCBs already and created a few of the circuits:
The other difference is that my circuit makes no attempts to interpret temperatures. CPU, GPUs, and motherboards already contain temperature monitoring embedded in the chips themselves. So, you can use SpeedFan or your motherboard's BIOS to interpret temperature levels, and adjust the PWM signal to your fan headers. The circuit simply turns PWM into a steady variable voltage.
The total size of the circuit is 1"x1.5". I have ordered the PCBs already and created a few of the circuits:
Last edited by dinofx on Wed Jun 07, 2006 11:09 am, edited 1 time in total.
Looks pretty good - am I right in thinking this does a similar job to the attenuator available with the T-balancer to smooth out PWM into a more analogue voltage signal? If so that's exactly the kind of thing we need more of (IMO) to fix PWM controllers. Do you have any plans to market these, and if so at what cost? Regardless, it's more than I could make, so good job.
-
- Posts: 1424
- Joined: Sun Dec 12, 2004 5:00 am
- Location: New York, NY
This is not like the attenuator. The MOSFET is precisely controlled to provide the exact amount of resistance needed for the desired voltage level, regardless of load. Also, it can handle up to 20 watts (as with water pumps). I have many of these available, $18 as a kit, or $35 soldered, assembled, and tested.Kizz wrote:Looks pretty good - am I right in thinking this does a similar job to the attenuator available with the T-balancer to smooth out PWM into a more analogue voltage signal? If so that's exactly the kind of thing we need more of (IMO) to fix PWM controllers. Do you have any plans to market these, and if so at what cost? Regardless, it's more than I could make, so good job.
If the attenuator is just a big capacitor, it might help, but it would mess up the linearity of the response to input.
-
- *Lifetime Patron*
- Posts: 5316
- Joined: Sat Jan 18, 2003 2:19 pm
- Location: St Louis (county) Missouri USA
I admire your ability to solder those surface mount resistors. However I doubt many modders attempting to assemble a kit, would find it so easy. Ruin one and finding another would be difficult.
Which brings up the cost of an assembled unit...not bad. But you are competing with some devices with similiar abilities(changing PWM to analog). M-Cubed has the Fan-Amp and the miniNG. Both in the price range, both come assembled with cables and temp sensors. Tough competition.
I'm past the point in my life where I would attempt such a soldering project....eyes not so good, hands not so steady. Maybe some people on SPCR might be braver......
Which brings up the cost of an assembled unit...not bad. But you are competing with some devices with similiar abilities(changing PWM to analog). M-Cubed has the Fan-Amp and the miniNG. Both in the price range, both come assembled with cables and temp sensors. Tough competition.
I'm past the point in my life where I would attempt such a soldering project....eyes not so good, hands not so steady. Maybe some people on SPCR might be braver......
It is easier than you might imagine. You simply put down a drop of solder on one of the pads, then line up the resistor and re-heat the pad. But, there is a 3rd option. SM components pre-soldered, you do the through-hole stuff. $25 +S&H.Bluefront wrote:I admire your ability to solder those surface mount resistors. However I doubt many modders attempting to assemble a kit, would find it so easy. Ruin one and finding another would be difficult.
Which brings up the cost of an assembled unit...not bad. But you are competing with some devices with similiar abilities(changing PWM to analog). M-Cubed has the Fan-Amp and the miniNG. Both in the price range, both come assembled with cables and temp sensors. Tough competition.
I'm past the point in my life where I would attempt such a soldering project....eyes not so good, hands not so steady. Maybe some people on SPCR might be braver......
Quite frankly, there is nothing else like this on the market, or I would have bought one. M-Cubed is huge, occupies a PCI slot, requires a USB port, and it has no way of monitoring your CPU's embedded temperature sensors. On a modern system, who gives a crap about adding analog temperature monitors? Your Motherboard, CPU, GPU, and even Hard Drives already report their temperatures to SpeedFan. M-cubed has no access to these temperatures, unless perhaps with the use of their software and a USB cable. Also, they use PWM for controlling fan speed, which means you get tachometer problems, and some people say more noise.
On the other hand, this circuit is small, elegant, and can function properly without ANY software, external wires, or USB ports. For example, in my Shuttle XPC, the BIOS can be set to "Smart" fan speed, in which case it increased my water pump and radiator fan speed with no software. I have a PWM fan for the radiator, and a second non-PWM fan also powered by this circuit.
-
- *Lifetime Patron*
- Posts: 5316
- Joined: Sat Jan 18, 2003 2:19 pm
- Location: St Louis (county) Missouri USA
Well I think you are talking about an M-Cubed T-Balancer......like what you describe. The M-Cubed FanAmp and miniNG are not USB connected....they are stand-alone fan controllers that can both run analog voltage.
I have a few of each. The Fan-Amp costs less than your unit....the miniNG costs slightly more. Neither require any software to run, in fact don't come with any. They use their temp sensors to control fan speed.....you cannot read the temps of these sensors.
The surface mount resistors would be the hard part of the soldering. The other things look easy....
I have a few of each. The Fan-Amp costs less than your unit....the miniNG costs slightly more. Neither require any software to run, in fact don't come with any. They use their temp sensors to control fan speed.....you cannot read the temps of these sensors.
The surface mount resistors would be the hard part of the soldering. The other things look easy....
-
- Posts: 333
- Joined: Wed Apr 05, 2006 9:54 pm
- Location: USA
Neat idea, I like it. Is the amplifier (LM741) set up to integrate the pulses and provide a proportional output, with a MOSFET to provide extra current?
Also, soldering 1206s isn't all that difficult, if you have a reasonably good iron, tweezers, and solder-wick to clean up any mistakes. Of course, I have younger eyes.
I am kind of confused, however, by why you couldn't just use the PWM output straight from the motherboard?
Also, soldering 1206s isn't all that difficult, if you have a reasonably good iron, tweezers, and solder-wick to clean up any mistakes. Of course, I have younger eyes.
I am kind of confused, however, by why you couldn't just use the PWM output straight from the motherboard?
Those sound similar. The only difference being that you are limited to input from two sensors that have to be installed in a less-than-ideal place. (I'm defining ideal as on my CPU Also, tuning the reponse I'm sure is more difficult. You have to start ramping up the speed at some lower temperature to ensure that it runs at 100% when your "max" temp is reached.Bluefront wrote:I have a few of each. The Fan-Amp costs less than your unit....the miniNG costs slightly more. Neither require any software to run, in fact don't come with any. They use their temp sensors to control fan speed.....you cannot read the temps of these sensors.
It's an RC filter, which converts the PWM into a low-side analog signal between 0 and 5 volts. The signal is then inverted, multiplied, shifted, etc. using the op-amp as an adder/subtractor circuit. The output of the MOSFET (rather than the opamps own output) is used for feedback.disphenoidal wrote:Neat idea, I like it. Is the amplifier (LM741) set up to integrate the pulses and provide a proportional output, with a MOSFET to provide extra current?
Also, soldering 1206s isn't all that difficult, if you have a reasonably good iron, tweezers, and solder-wick to clean up any mistakes. Of course, I have younger eyes.
I am kind of confused, however, by why you couldn't just use the PWM output straight from the motherboard?
I just used my index finger to hold down the resistors. That way I knew they weren't getting too hot to be damaged
What do you mean by using the PWM directly? A PWM fan can do this because it is always receiving power for the Tach. Even if I didn't care about tach, my water pump has an internal capacitor, which means you can't get a linear response from the duty cycle. At 50%, the pump would basically draw twice as much current half the time, and run off the capacitor when the current is cut.
Here is a review of the MiniNG. It has some drawbacks, including difficult configuration, slow response time, and tricky temp. probe placement.
I know that my Pentium 4 with EIST and SpeedStep can change thermal output considerably over a very short period of time. I didn't get a good feeling for how quickly MiniNG adjusts its fan speeds, but I hope its not on the order of minutes.
http://forums.silentpcreview.com/viewtopic.php?t=31588
I know that my Pentium 4 with EIST and SpeedStep can change thermal output considerably over a very short period of time. I didn't get a good feeling for how quickly MiniNG adjusts its fan speeds, but I hope its not on the order of minutes.
http://forums.silentpcreview.com/viewtopic.php?t=31588
-
- *Lifetime Patron*
- Posts: 5316
- Joined: Sat Jan 18, 2003 2:19 pm
- Location: St Louis (county) Missouri USA
Actually the FanAmp is more similar to your device than the miniNG. I have been using two in different computers for a while now. I never did a real review, because of the boards I was using.
The FanAmp has a connector to a MB fan header, a header that has MB fan control. If your board can automatically adjust fan voltage from 7-12V, the fan amp can use that signal to automatically send an analog voltage to your fan. It gets power from a molex connector, and has a temp sensor if your board doesn't support fan control.
It is a simpler device than a miniNG, but with some similarities. Your device is also similar in it's operation. Unfortunately, I never tried the FanAmp with a MB that supported fan control, so I don't know how well that function works....
The FanAmp has a connector to a MB fan header, a header that has MB fan control. If your board can automatically adjust fan voltage from 7-12V, the fan amp can use that signal to automatically send an analog voltage to your fan. It gets power from a molex connector, and has a temp sensor if your board doesn't support fan control.
It is a simpler device than a miniNG, but with some similarities. Your device is also similar in it's operation. Unfortunately, I never tried the FanAmp with a MB that supported fan control, so I don't know how well that function works....
The more recent motherboards are switching to PWM to control fan speed using 4-pin headers. My circuit is only suited for these newer motherboards. Almost all socket 775 MBs have at least on such 4-pin PWM fan header, since Intel ships such a fan with their CPUs.Bluefront wrote:The FanAmp has a connector to a MB fan header, a header that has MB fan control. If your board can automatically adjust fan voltage from 7-12V, the fan amp can use that signal to automatically send an analog voltage to your fan. It gets power from a molex connector, and has a temp sensor if your board doesn't support fan control.
So, fan amp is designed for motherboards which actually varry the output voltage at a 3-pin fan header. If a motherboard has this capability, it essentially has a FanAmp built-in and I don't see the purpose of buying a fan amp for a fan amp. I guess the only purpose is to boost the power handling and possibly lower the bottom end range using manual tuning of the pots.
By changing the resistors on my circuit, you can get linear control from 6-12V, instead of 7.4-12V. By coincidence, replacing every resistor with 100K does the trick. I could probably detemine the resistors required for any desired control range, but I only have 47, 68, 82, and 100 in my possession to work with.
-
- *Lifetime Patron*
- Posts: 5316
- Joined: Sat Jan 18, 2003 2:19 pm
- Location: St Louis (county) Missouri USA
You're right about the FanAmp....it can handle a lot more current than the MB header. And you can manually adjust the idle speed. And using the second pot and the supplied sensor, you can manually set a temperature that will turn the fan to full speed. And it does work well not connected to the MB....that's how I use mine.
-
- *Lifetime Patron*
- Posts: 5316
- Joined: Sat Jan 18, 2003 2:19 pm
- Location: St Louis (county) Missouri USA
Here's the specs from the M-Cubed site...
"FanAmp is designed specifically for 1-channel fan systems, for semi-passive cooled systems or for safety fans in passive cooled systems. The FanAmp is easily adjustable with 2 poties. FanAmp makes it also possible to convert the mainboard signals (7-12V) into a wider range of 0-12V. This features make zero fan speed controllable with any mainboard tool. Performance: 25W permanent
Package contents:
1 analog temperature sensor, control unit, motherboard cable"
"FanAmp is designed specifically for 1-channel fan systems, for semi-passive cooled systems or for safety fans in passive cooled systems. The FanAmp is easily adjustable with 2 poties. FanAmp makes it also possible to convert the mainboard signals (7-12V) into a wider range of 0-12V. This features make zero fan speed controllable with any mainboard tool. Performance: 25W permanent
Package contents:
1 analog temperature sensor, control unit, motherboard cable"
Dinofx, sorry for newbie question, but will your circuit work on 3-wires input from the motherboard or is the PWM the fourth wire?
I'm trying to find a mini-ITX motherboard which will enable me to control case and CPU fan speeds using Speedfan and the on-board sensors, but am having no luck. From what I read I assume that I need a motherboard with 4-wire fan outputs, i.e. it cannot control fan speeds just using 3 wires?
I'd love to be able to use your circuit to quieten the fans in my Hoojum case...
Thanks
I'm trying to find a mini-ITX motherboard which will enable me to control case and CPU fan speeds using Speedfan and the on-board sensors, but am having no luck. From what I read I assume that I need a motherboard with 4-wire fan outputs, i.e. it cannot control fan speeds just using 3 wires?
I'd love to be able to use your circuit to quieten the fans in my Hoojum case...
Thanks
Last edited by leem on Tue Jul 25, 2006 4:23 pm, edited 1 time in total.
Just curious, why two-pin headers instead of three-pin?
One nice feature of the NMT-2 and -3 is pass-through of the RPM sense signal on the third pin. That way you can use standard fan connectors.
Your device with 3-pin headers would be ideal for PWM motherboards and standard fans (no need to replace connectors).
I was all set to order one until I noticed this...
One nice feature of the NMT-2 and -3 is pass-through of the RPM sense signal on the third pin. That way you can use standard fan connectors.
Your device with 3-pin headers would be ideal for PWM motherboards and standard fans (no need to replace connectors).
I was all set to order one until I noticed this...
I'm new here, but I can comment a bit more on the FanAmp since I've been struggling with it for several weeks, and working (at a snails pace) with m-Cubed tech support (and a language barrier) to figure it out....Bluefront wrote:Here's the specs from the M-Cubed site...
"FanAmp is designed specifically for 1-channel fan systems, for semi-passive cooled systems or for safety fans in passive cooled systems. The FanAmp is easily adjustable with 2 poties. FanAmp makes it also possible to convert the mainboard signals (7-12V) into a wider range of 0-12V. This features make zero fan speed controllable with any mainboard tool. Performance: 25W permanent
Package contents:
1 analog temperature sensor, control unit, motherboard cable"
The FanAmp DOES NOT CONVERT PWM TO DC ANALOG! I thought it did, but after several e-mails I discovered it does not. It is designed to do DC analog to DC analog range conversion.
I was looking around the 'net to find some circuits to do PWM to analog conversion, and there are several. The problem was building it. I think Dinofx's widget fills a great need that nothing yet solves.
So, I take it since your assumption is flawed, you're ready to place your order . There are two 3-pin headers for two normal fans. The 2-pin headers are for plugging in the power and MB. It only takes a single pin to send the RPM signal to the motherboard. So, the tach singal from one of the fans *is* passed-through.cmthomson wrote:Just curious, why two-pin headers instead of three-pin?
One nice feature of the NMT-2 and -3 is pass-through of the RPM sense signal on the third pin. That way you can use standard fan connectors.
Your device with 3-pin headers would be ideal for PWM motherboards and standard fans (no need to replace connectors).
I was all set to order one until I noticed this...
The two 2-pin headers are basically the typical 4-pin connection to the motherboard. They are Tach, PWM, Ground, and +12V. Because they are side-by-side, you can use a single 4-pin terminal housing, or two 2-pin housings, to allow the wires to be separately (dis)connected. Because water pumps would require a lot of juice, it is possible to use your PSU for power source, and the motherboard only for the in/out signals.
you also have a market in those who have the m-Cubed T-ban, and want proper DC outputs to some of their devices. The T-ban digital doesn't do this as stock, and the attenuators only help a little. The T-ban kicks out PWM but it isnt a square-wave, they says its like a sine wave from 0v-12v-0v etc. I think the attenuator changes this to say 5v-10v-5v or something similar. Do you know if your circuit will handle this unique (i think) type of PWM and give a solid DC output?
The T-ban can quite simply be hooked into Motherboard Monitor to use the on-board sensors or both the onboard and the externals (highest counts) to give protection during a crash. The other advantage i found is putting a sensor in the PSU and hooking up that fan to the T-ban giving me a much quieter zalman 300w at idle/normal than using the thermistor.
The T-ban can quite simply be hooked into Motherboard Monitor to use the on-board sensors or both the onboard and the externals (highest counts) to give protection during a crash. The other advantage i found is putting a sensor in the PSU and hooking up that fan to the T-ban giving me a much quieter zalman 300w at idle/normal than using the thermistor.
Doh!dinofx wrote:So, I take it since your assumption is flawed, you're ready to place your order . There are two 3-pin headers for two normal fans. The 2-pin headers are for plugging in the power and MB. It only takes a single pin to send the RPM signal to the motherboard. So, the tach singal from one of the fans *is* passed-through.
I definitely should have looked closer... BTW, you might want to edit that (much better) picture into the initial post.
Are the two tach pins of the two 3-pin connectors wired together, or is the upper one left NC? I.e., do you need to cut/pull out one of the tach wires in a two-fan system (and be careful which one)?
I have been using this circuit without problems for many months. Another modder recently used one in his AMD-based motherboard. It worked perfectly, although that particular motherboard required a fan with tachometer signal or else you could not reduce the speed. I have 3 assembled boards ready for use.
-
- Site Admin
- Posts: 12285
- Joined: Sun Aug 11, 2002 3:26 pm
- Location: Vancouver, BC, Canada
- Contact:
dinofx -- This is a fantastic device. I'd like to get a hold of a couple to review! Pls email me about this.
Also, you should know that I've seen in a recent Gigabyte(?) AM2 board fan controls in the BIOS that includes a switch between PWM and voltage control. This is on a board with a 4-pin CPU fan header. I think the board makers are taking the fan control chip developed and specified by Intel for their boards and putting them in AM2 boards -- probably to save on $ & time.
sjschwinn -- You said The FanAmp DOES NOT CONVERT PWM TO DC ANALOG! I would like to hear more about this. We have a reviewer who is about to start work on mCubed fan controllers...
Ditto, Myth! -- I'd like to hear more about your knowledge of the T-ban.
Also, you should know that I've seen in a recent Gigabyte(?) AM2 board fan controls in the BIOS that includes a switch between PWM and voltage control. This is on a board with a 4-pin CPU fan header. I think the board makers are taking the fan control chip developed and specified by Intel for their boards and putting them in AM2 boards -- probably to save on $ & time.
sjschwinn -- You said The FanAmp DOES NOT CONVERT PWM TO DC ANALOG! I would like to hear more about this. We have a reviewer who is about to start work on mCubed fan controllers...
Ditto, Myth! -- I'd like to hear more about your knowledge of the T-ban.