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DIY Voltage Controlled Scalable PWM Controller - Page 3

post #21 of 76
Quote:
Originally Posted by givmedew View Post

Well if you end up designing a PCB that I can just drop the parts onto and solder I would be interested in it. This is great and def something I would love to have.

Same here, this is awesome. I've always wanted some sort of manual pwm control.

I would donate to a kickstarter or something like that.
Quote:
Originally Posted by IT Diva View Post

Most higher end fan controllers have integrated temp sensors and control the fan speed based on a user selected setpoint if you want them to.


That's one of Lamptron's claims for the new CW611, that it's suited particularly to temp based pump control.


Darlene

I've been interested in the CW611. The one gripe that I have is that you can't run every channel off of one sensor. I was wondering if its possible to just splice a few pigtails onto a single temp sensor. I'm not really sure how they work or if it could cause any issues.
Edited by BababooeyHTJ - 5/28/13 at 5:49pm
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i5 3570k Gigabyte Z77X-UD5H MSI TF3 7950 Tri-fire Samsung 30nm 4x4GB 
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post #22 of 76
Thread Starter 
Quote:
Originally Posted by BababooeyHTJ View Post

Same here, this is awesome. I've always wanted some sort of manual pwm control.

I would donate to a kickstarter or something like that.
I've been interested in the CW611. The one gripe that I have is that you can't run every channel off of one sensor. I was wondering if its possible to just splice a few pigtails onto a single temp sensor. I'm not really sure how they work or if it could cause any issues.


You can't just splice them together.

Each sensor is a resistor that varies its resistance as a function of temperature, and each channel is designed for that 10K resistance at a preset ambient.

When you connect sensors together, you drop or add resistance depending on the connections.

If you need all channels to run off one sensor, why not just plug each channel's sensor in, and place them all in the same place so they see the same temp.

Darlene
post #23 of 76
Thread Starter 
Wooo hoooo . . .

My new CW611's came today.

Also I just about finished the perfboard version of the smaller protoboard with all the interface pigtails and connections added.

I plugged it up to the main protoboard and it's working perfectly.


I'll be testing it on one of the dual res / dual D5 assemblies later in the week.


Darlene






]

post #24 of 76
Darlene,

What is the real advantage in using Pwm to control fan instead of just voltage. I could think varing the pulse width would cause more noise. I know lower the voltage raises the amps as the fans need so much watts but?.. I don't see the advantage I would think the Pwm would cause more noise in whole system????

Also a another question do you think it really makes much of a difference if you add to the length of the temp sensors?? I know they are rtd sensors so was wondering if it would make a difference I can see?
Edited by seross69 - 5/29/13 at 2:23am
post #25 of 76
Thread Starter 
Quote:
Originally Posted by seross69 View Post

Darlene,

What is the real advantage in using Pwm to control fan instead of just voltage. I could think varing the pulse width would cause more noise. I know lower the voltage raises the amps as the fans need so much watts but?.. I don't see the advantage I would think the Pwm would cause more noise in whole system????

Also a another question do you think it really makes much of a difference if you add to the length of the temp sensors?? I know they are rtd sensors so was wondering if it would make a difference I can see?


The real advantage of PWM is that it preserves the torque at less than max rpm speeds.

That means a PWM fan or pump can and will start from off at very low speeds, and can run at lower speeds than its undervolted counterpart.


Here's why: (at slight risk of oversimplification)

Fans or pumps do not draw more current when you reduce the voltage, as the voltage drops, the current drops proportionally, and the actual power level drop is a square relationship.

To use some simple numbers, let's take a pump, and at 12V it has a 2 amp draw, that's 24 watts and see what happens as we drop the voltage . . .

Reduce the voltage to 6 volts, and the current will drop to 1 amp, which gives 6 watts

half the voltage . . .half the current . . . . 1/4 the power


Now lets see what happens if it's a PWM pump:

12V with a 100% duty cycle, the same 2 amp draw, and the same 24 Watts of power

Now reduce the duty cycle to 50% . . . . 12v at 2amps, that's 24W, but for half the time during each pulse interval, so effectively 12W

That's twice the actual power to the pump at 50% duty cycle as at half the voltage.

That's why PWM has better torque at lower speeds, and allows things to run slower and therefor quieter than variable voltage control.


Pumps and fans designed for PWM control have advanced motors and onboard electronics to implement it, so there is no additional "noise".


Trying to use a pulse modulated supply voltage to effect speed control over fans or pumps not designed to be controlled that way is another matter al together.

You can get all manner of garbage going that route.

The PWM control standard for PCs is for a 25KHz frequency, that's a pulse every 40 microseconds.

Cheaply made, low parts count, PWM generators have a terrible tendency to shift frequency considerably lower as the pulse width shortens to effect slower speeds. and worse, not all started at the 25KHz spec.


Once they shift low enough to be into the audio range, you'll get that "buzzing" which is the fan or pump tuning on with each pulse.


Adding length to resistive sensors has no effect, as long as the connection is secure, solder is the best.

Sensors are nominally 10,000 Ohms at about 24C ambient. The resistance of the wires would be in the thousandths of an Ohm per foot.

It would take hundreds of feet of the relatively small gage wire used for sensors to effect a single degree of error.

Twisted splices, on the other hand, will end up being a nightmare.


Hope that all helps,

Darlene
Edited by IT Diva - 5/29/13 at 5:34am
post #26 of 76
Quote:
Originally Posted by seross69 View Post

Darlene,

What is the real advantage in using Pwm to control fan instead of just voltage. I could think varing the pulse width would cause more noise. I know lower the voltage raises the amps as the fans need so much watts but?.. I don't see the advantage I would think the Pwm would cause more noise in whole system????

Few little tidbits, assuming you are talking about buzzing/humming most people experience, that is directly related to controlling 3-pin fans via pwm. Meaning, take a standard fan, and vary the 12 volt signal via pwm, so the controler outputs 0 to 12 volts on the main power line of the 3-pin fan. Because most fans arent designed for that, you get odd behavior and noise

What Darlene is doing is specifically for 4-pin pwm fans/pumps.

The layout of 4-pin fan's pins: 12volt power, ground, tach signal and 5volt control signal. All 4-pin fans/pumps have an additional circuit board on them. This board basically controls the 12 volt power via pwm internally, but because the circuit is designed specifically for that fan/pump, you dont get any buzzing.

What 4-pin pwm controllers and 4-pin motherboard headers do is provide a constant 12 volt power signal to the fan/pump, and send a variable 5 volt signal on the control line. Then the fan/pump onboard circuitry will translate that variable control signal to a corresponding fan/pump speed using the 12 volt power signal.

Best part about this, IMO? You can split the fan's header into two pieces. One piece can have the 5 volt control signal and the tach signal. The second piece can have the 12 volt power signal and ground. Plug the first header to your 4-pin mobo header or fan controller. Plug the second header directly into your PSU.

Now you don't have to worry about silly things like maximum wattage a fan controller can handle. Daisy chain the same 5 volt control signal across a million fans, with your fans plugged into your psu. Now your psu's max wattage is all you have to worry about. No more blowing up fan controllers or limiting the number of fans on one header.

Ultimate control, packaged very nicely with ultimate component safety. *Insert diabolical here*

The idea she is trying to implement is to create a device that would piggyback onto a standard 12 volt voltage regulating fan controller's header. So regular controllers designed for 3-pin fans and pumps. Connect this piggyback device to one of the fan headers of the controller, so that it recieves the controller's variable 0 to 12 volt signal. Then the piggyback will translate that 0 to 12 signal to a 0 to 5 volt signal which a 4-pin pwm fan/pump can accept on its 5 Volt control signal line.

...now any 3-pin fan controller can be used with 4-pin fans.

Pretty sweet, right? biggrin.gif
post #27 of 76
Thread Starter 
Quote:
Originally Posted by NimbleJack View Post

Few little tidbits, assuming you are talking about buzzing/humming most people experience, that is directly related to controlling 3-pin fans via pwm. Meaning, take a standard fan, and vary the 12 volt signal via pwm, so the controler outputs 0 to 12 volts on the main power line of the 3-pin fan. Because most fans arent designed for that, you get odd behavior and noise

What Darlene is doing is specifically for 4-pin pwm fans/pumps.

The layout of 4-pin fan's pins: 12volt power, ground, tach signal and 5volt control signal. All 4-pin fans/pumps have an additional circuit board on them. This board basically controls the 12 volt power via pwm internally, but because the circuit is designed specifically for that fan/pump, you dont get any buzzing.

What 4-pin pwm controllers and 4-pin motherboard headers do is provide a constant 12 volt power signal to the fan/pump, and send a variable 5 volt signal on the control line. Then the fan/pump onboard circuitry will translate that variable control signal to a corresponding fan/pump speed using the 12 volt power signal.

Best part about this, IMO? You can split the fan's header into two pieces. One piece can have the 5 volt control signal and the tach signal. The second piece can have the 12 volt power signal and ground. Plug the first header to your 4-pin mobo header or fan controller. Plug the second header directly into your PSU.

Now you don't have to worry about silly things like maximum wattage a fan controller can handle. Daisy chain the same 5 volt control signal across a million fans, with your fans plugged into your psu. Now your psu's max wattage is all you have to worry about. No more blowing up fan controllers or limiting the number of fans on one header.

Ultimate control, packaged very nicely with ultimate component safety. *Insert diabolical here*

The idea she is trying to implement is to create a device that would piggyback onto a standard 12 volt voltage regulating fan controller's header. So regular controllers designed for 3-pin fans and pumps. Connect this piggyback device to one of the fan headers of the controller, so that it recieves the controller's variable 0 to 12 volt signal. Then the piggyback will translate that 0 to 12 signal to a 0 to 5 volt signal which a 4-pin pwm fan/pump can accept on its 5 Volt control signal line.

...now any 3-pin fan controller can be used with 4-pin fans.

Pretty sweet, right? biggrin.gif


The PWM control signal is not a variable voltage.


It's a series of 5V pulses with variable widths that control the "on time" of the PWM controlled device .

At anything less than 100%, but more than 0% duty cycle, which would be a continuous 5V signal and continuous 0V signal respectively, there is a 5V pulse that starts every 40 microseconds. (based on the 25KHz PWM standard)

Depending on how long the pulse stays at 5V before going to 0V out of each of those 40 microsecond intervals, is how long the pump is turned on with it's full 12V supply power out of each 40 microsecond interval.

If the pulse is at 5V for 20 microseconds and then turns off to 0V for the next 20 microseconds before the next pulse starts, that would be 20 divided by 40, or 50% duty cycle.


Go back to the first page and look at the pics with the scope traces.

With what I've explained, they may be more understandable now. You can see the pulse has varying time intervals at 5V, the upper portion on the screen, but that from the start of one pulse to the start of the next pulse, is always half the screen width.

Darlene
post #28 of 76
I think NimbleJack meant 0 or 5 volt, which would have been correct.

I do have a bit of an off-topic question, but I have the feeling for you (darlene) it's just a 2 second answer, since I don't really need more than that.
I just need to know if it's possible to make a voltage-controlled resistor. So 6V input would result in a 10kOhm resistance, 9V would be 5kOhm and 12V would be 0kOhm and every value in-between.
Really hope this is possible cause that would give me a 170 to 2000 rpm range on my AP182's.
post #29 of 76
Thread Starter 
Quote:
Originally Posted by Jetskyer View Post

I think NimbleJack meant 0 or 5 volt, which would have been correct.

I do have a bit of an off-topic question, but I have the feeling for you (darlene) it's just a 2 second answer, since I don't really need more than that.
I just need to know if it's possible to make a voltage-controlled resistor. So 6V input would result in a 10kOhm resistance, 9V would be 5kOhm and 12V would be 0kOhm and every value in-between.
Really hope this is possible cause that would give me a 170 to 2000 rpm range on my AP182's.

It's not exactly a 2 second answer . . . .

I'm guessing that you have measured the speed control pot on the fan's speed control at 10K, and want a way to replace it with something a fan controller can control?


The best way to do that would be with a digi pot and a PIC microcontroller chip.

It would take some circuitry, a PIC programmer to program the microcontroller chip, and someone to write the program.


Basically, there's no easy way, and I don't offhand know of an IC chip that performs that function.

Darlene
post #30 of 76
Quote:
Originally Posted by IT Diva View Post

Quote:
Originally Posted by NimbleJack View Post

The idea she is trying to implement is to create a device that would piggyback onto a standard 12 volt voltage regulating fan controller's header. So regular controllers designed for 3-pin fans and pumps. Connect this piggyback device to one of the fan headers of the controller, so that it recieves the controller's variable 0 to 12 volt signal. Then the piggyback will translate that 0 to 12 signal to a 0 to 5 volt signal which a 4-pin pwm fan/pump can accept on its 5 Volt control signal line.


The PWM control signal is not a variable voltage.


It's a series of 5V pulses with variable widths that control the "on time" of the PWM controlled device .

Sorry, i understand that the 5v signal is pwm, i put that explaination together a bit too quick redface.gif

I nailed everything else though, didnt i? thumb.gif

...i hope so anyways LOL biggrin.gif
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