Caframo fan speed control

[s/v Jedi]

Originally Posted by conachair

Not quite right again I'm afraid....., the buck/boost linked to above *is* PWM. 180Khz on the buck output apparently.
WHy did you think it has 2 big inductors on there?
Though with 470uF caps on the output, yours looks like 100uF so your output voltage might be a bit choppier.

And has CV & CC so limits power to whatever you want, voltage or current - whichever set point it hits first. Your board is dumb, no control at all away from factory set points, and 7A is enough to let a lot of smelly magic smoke out... Plus unlikely to output battery voltage, just tried another pWM buck, 11.6v max output for a 12.6v input.

All this time and Ohms law was wrong all along, eh

Overview of the power supply, really handy for anyone digging deeper than 'is it on?'.

You are not new here so you must know I am an electronics designer-engineer. So, being surprised at your reaction, I double checked and read the documentation. It does indeed say it can do CV as well as CC so good, I was wrong there because I only read the title where the CV part was omitted. Weird because normally this is advertised as a CV/CC power supply but my bad for not reading the full description.

But that is where it ends. I’m pretty sure you don’t like it when I start schooling you on PWM but your snarky Ohms law comment justifies you being slapped here a bit: you are wrong. Your own graphs, as well as the power supply documentation confirm that I am right and this is a regulated DC power supply, not a PWM output like a dimmer does.

I know the concept is tough so I’ll use layman terms: when you connect the fan straight to 12V but switch it on and off really quick, like thousands of times a second, it will run slower. Still 12V though, never 11, 10, 13 or anything else than input voltage.

The power supply you have uses a switching design which somewhat looks like PWM -internally- but the output is a non-pwm regulated DC supply. The inductors you see are actually used as a high frequency transformer and for filtering.

Now the buck/boost part: in order to make 12V DC out of 9V DC, this buck/boost design is required. It takes the input DC and applies a 50% duty cycle pwm at some high frequency like 40kHz, which makes it a 40kHz square wave, which can be transformed up to a higher voltage, after which it is rectified and stabilized, then fed to a regulator where the desired voltage is set. The high frequency is used because it is much more efficient so that a very small (cheap) transformer can be used.

A PWM dimmer outputs the same voltage as it is fed, but allows you to change the duty cycle from 100% (always on, full power transfer) down to 0% (always off, no power transfer). Any intermediate setting is a pulsed output with the width of the pulse on a 1:1 relationship to the duty cycle but at the same voltage as it’s input.

This is how it is. When a fan has a switch with high power resistors, it works by lowering the voltage to the fan motor. When it has a little circuit board, it uses PWM output just like a dimmer for a lamp. This is why a dimmer is the logical replacement, instead of a regulated power supply.

[s/v Jedi]

Originally Posted by a64pilot

The Carafamo fans are cute, but noisy for their output and not all that efficient.

For a very quiet and extremely efficient fan as in power consumption vs air output, this is your fan. It comes with a 110V wall wart, but it’s native 24VDC, so I run a 12 to 24 converter, you of course would run it direct.
It’s an excellent quiet table fan, one oscillates and blows air through the whole salon, and is virtually silent at half speed or less.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

We have used a bladeless fan (Dyson knockoff) for years and like it better than the marine DC fans. In the end it gave up the ghost and I replaced it with this one which is really cheap but works great... at 110V AC
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[conachair]

Originally Posted by s/v Jedi

The power supply you have uses a switching design which somewhat looks like PWM -internally- but the output is a non-pwm regulated DC supply.

Bit more than looks like on the output -

The XL4016 is a 180 KHz fixed frequency
PWM buck (step-down) DC/DC converter,
capable of driving a 8A load with high
efficiency

http://www.xlsemi.com/datasheet/xl4016%20datasheet.pdf

So I think what your saying is that a PWM buck converter with smoothing on the output isn't PWM anymore???

So your unit has no filters on the output to smooth the PWM?

Must be *really* noisy.

[s/v Jedi]

Originally Posted by conachair

Bit more than looks like on the output -

http://www.xlsemi.com/datasheet/xl4016%20datasheet.pdf

So I think what your saying is that a PWM buck converter with smoothing on the output isn't PWM anymore???

So your unit has no filters on the output to smooth the PWM?

Must be *really* noisy.

That is how a dimmer and PWM speed control works. The good thing is that the motor runs on the voltage it is designed for

[Rjt]

I’ve installed this one about 4 months ago. East coast Australia. Used it a fair bit.
https://www.ebay.com.au/itm/Digital-....c100012.m1985
Works fine. There are probably cheaper controllers, but this one suited me.

[s/v Jedi]

Originally Posted by Rjt

I’ve installed this one about 4 months ago. East coast Australia. Used it a fair bit.
https://www.ebay.com.au/itm/Digital-....c100012.m1985
Works fine. There are probably cheaper controllers, but this one suited me.

Wow that one does up to 20 amp continuous :thumb

I’m sure it’s a matter of time before the perfect gadget is found on eBay or Amazon

[s/v Jedi]

Here’s one under $4 that may work
https://www.ebay.com/itm/DC-6-30V-12...f58d8ff9e86708

[s/v Jedi]

I’m getting good at this: $3.51 with free shipping: https://www.ebay.com/itm/12V-40V-10A....c100005.m1851

[noelex 77]

The Caframo fans have a low power draw. Around 0.1-0.4 A @ 12v is typical.

Some of the speed control devices are very power efficient, while others can be poor. Some have a reasonable parasitic draw. Anything with an LED display is likely to consume more power. In many applications this is justified, but not all.

These are only small amounts in the overall power budget, but it is not hard to double the fan consumption with some choices. Small low draw devices that are on for a long time or have a significant parasitic draw can have more of an impact than may be imagined.

At least consider the power implications with the choices you make.

[Sternwake]

I have a lot of experience speed controlling powerful 92mm and 120mm Delta brand as well as other brand computer fans, and a few brushed motor fans by both PWM motor speed control and by voltage buck converters.

Those LED dimmers linked earlier certainly work to reduce fan speeds, however they are something like 11 to 13khz. Every fan I have speed controlled using these dimmers has made an irritating whining sound at reduced speeds, and I have phased out each and everyt PWM LED dimmer for both led dimming and fan speed reduction, in favor of a voltage bucker.

If one wants the PWM motor speed controller, search for one that specs 21KHZ or higher.

The 21khz PWM MSCs are nice because they come with a nice finger twist potentiometer, rather than a trimpot that requires a jeweler's screwdriver and some magnification and a steady hand to manipulate.

I have been using voltage buckers, 5 amp rated with a XL4015 chipset, rather than the older LM2596 3 amp chip. The XL4015 drops only 0.3v. 12.0v in 11.7v out max. This has not been a factor with the powerful Delta computer fans I have been using, and if it were I could negate that 0.3v loss by thicker wiring feeding the bucker. I don't see the need to use a buck/boost converter on a 12v fan. I use those on 24v fans. I also used a buck boost converter on a light housing, but much above 14v and it would exceed the rating of the bucker whereas at 12.8v it was at half the rating. The current limiting pot came in handy on this light.

The current limiting potentiometer is also nice on the 24v fan, as I limit it to 2.4 amps, and then voltage will not exceed 29.5v or so on the particular 24v Papst fan, otherwise the booster would take it towards 36 volts.

I use a 60 amp PWM 21khz motor speed controller on the blower motor on my Vehicle, instead of the 4 resistor speeds. It does not even get warm passing 15 amps for 30 minutes, and I can run it with the ignition off, and no whining.

All my voltage buckers, I remove the tiny voltage trimpot and replace them with wires to a better potentiometer, usually a ten turn 10K ohm, but some of the units spec 50K ohm pots. Only two wires need to goto the pot from circuit board on all the units I have used.

Some of the voltage bucker's have a current limiting pot too, but the units without are physically smaller and I prefer them.
The current limiting pot also works to reduce fan speed or led light brightness, but seems to use more electricity at the same dimness/speed levels, so I use the voltage potentiometer instead for speed and lumen control. The current limiting pot on leds also has them shut off completely when dimmed low where the voltage pot will have them dim all the way to barely visible.

The 5 amp XL 4015 buckers, the main chip stays cool at a constant 2.5 amps, and many do come with stick on heatsinks to stick atop the chip. The LM2596 3 amp chips would get much hotter powering the same fans and would have more voltage drop across them than the 0.3v of the xl4015 based buckers, but i cannot remember how much nor easily test one for that figure at the moment.

Some of the buckers have leds, some do not, some come with stick on heatsinks, some do not. Some come with 50K ohm trimpots, some come with 10K ohm. The following link is a 50K ohm one(503), I prefer those with 10K ohm as 10K ohm bourns pots seem more readily available and less expensive.

I have no experience with this particular seller, and the buckers I prefer have the wirewound toroid layed flat on the circuit board rather than standing on edge. Use some rtv or something similar like amazing goop, to keep vibrations from fatiguing them.

https://www.ebay.com/itm/5A-XL4015-D...AAAOSw5PRdBa8w

I have removed almost all the PWM LED dimmers in favor of these buckers. The PWM dimmers would not dim the powerful LED's low enough before they would shut down and had flickering issues. The 150Khz XL4015 voltage buckers have no issues with flickering and can dim the leds I am using all the way to the point they can barely be seen.

Removing the trimpots and replacing them with wires takes some soldering skills and can be a bit frustrating, but I much prefer Vbuckers over the PWM MSC for dimming leds or lowering fan speeds. The 'insert stranded wire crush under screw' type of terminals available on some of the buckers have been problematic in my experience, but I've also had issues shorting them using test leads where the jaw bridges + and -.

[GILow]

Originally Posted by noelex 77

The Caframo fans have a low power draw. Around 0.1-0.4 A @ 12v is typical.



Some of the speed control devices are very power efficient, while others can be poor. Some have a reasonable parasitic draw. Anything with an LED display is likely to consume more power. In many applications this is justified, but not all.



These are only small amounts in the overall power budget, but it is not hard to double the fan consumption with some choices. Small low draw devices that are on for a long time or have a significant parasitic draw can have more of an impact than may be imagined.



At least consider the power implications with the choices you make.

Actually, I was having a chuckle at the LED and LCD display units.

Back when I worked in I.T. we referred to such displays as E.F.S. Executive Fascination System. We noticed how senior management always wanted lots of pretty lights. I remember the look of profound disappointment on the face of the managing director of one company when he asked to see the wonderful new Cisco routers I had purchased to link all the offices in the company. He felt his $100K should have bought him more than just a single status light.

No, I don’t want my fan dazzling me with numbers while I am trying to sleep, I’ll stick to the displayless sort myself. I was actually celebrating the fact that I will be able to get rid of the annoying power light on the fans by going this path.

[GILow]

Originally Posted by s/v Jedi

I’m getting good at this: $3.51 with free shipping: https://www.ebay.com/itm/12V-40V-10A....c100005.m1851

Yes you are. I hope I haven’t started something.

[jamhass]

Bill (wsmurdoch) has the best answer. Simple, cheap and unlikely to cause rf interference (which pwm might do).