Caframo fan speed control

[conachair]

Originally Posted by s/v Jedi

The dimmer I linked to can be used to test things,

If you like paying over the odds for something really not very well suited to testing that is...

Far better (and safer) idea is ....
https://www.amazon.co.uk/s?k=d3806&i...ref=nb_sb_noss

[GILow]

Originally Posted by s/v Jedi

This is a high quality pwm dimmer used for airplane dash lighting. If something works with a pwm dimmer and it is within the power rating of this one, then it will work and concept is proven.

If you buy a cheap one and it doesn’t work, then you know nothing because it may be one that is already broken or too cheap to reach rated output etc.



The dimmer I linked to can be used to test things, to dim cabin lights etc. It’s just too expensive to waste on a dumpster find.

Well, there is merit in your logic, I’ll grant you that.

[Matt Johnson]

Keep us updated. I have three of the Caframo two blades fans with broken switches for low power and need to do something about them before summer.

-Matt

[GILow]

Originally Posted by funjohnson

Keep us updated. I have three of the Caframo two blades fans with broken switches for low power and need to do something about them before summer.



-Matt

Will do.

Actually, you’ve reminded me, I’ve got to reinstall my working fans real soon. We’ve got 40 degrees C forecast for Saturday.

[conachair]

Originally Posted by GILow

Well, there is merit in your logic, I’ll grant you that.

Bear in mind that looks like just a buck PWM controller, it will never get to battery voltage, so you'll never get to full speed . Buck/boost converters are on ebay cheap. Best to do a youtube or google search for reviews, though you might have to hunt around to find one with a nice knob for day to day control.

[a64pilot]

It will work, I am 99% sure that is what a model airplane speed controller is, except of course some see huge amperage.
I believe running at partial power a motor will last much longer than full current.
Get a cheap PWM light dimmer, and as someone else posted, turn the fans off if your going to use the HF radio.

I have used several of these, $3 ea and will hold 8 amps, and I’ve not noticed any noise on the radio, but perhaps they were off too.
Mount them with Velcro

[a64pilot]

These also work well and you can hide them as the controller is RF, unfortunately though one controller will control all of them so just turning on one by the controller may not work.
Still $3 ea though

[s/v Jedi]

Originally Posted by conachair

If you like paying over the odds for something really not very well suited to testing that is...

Far better (and safer) idea is ....
https://www.amazon.co.uk/s?k=d3806&i...ref=nb_sb_noss

I don’t know where you got the idea that a constant current supply is the right choice for a fan or safer than a 12V pwm dimmer. Yourlink shows a device that requires connectors instead of simple screw terminals so I still think my option is much easier, as safe as anything and last but not least it is a pwm output device designed for slowing down fans. I believe a CC source may just run the fan at full speed.

[conachair]

Originally Posted by s/v Jedi

I don’t know where you got the idea that a constant current supply is the right choice for a fan or safer than a 12V pwm dimmer. Yourlink shows a device that requires connectors instead of simple screw terminals so I still think my option is much easier, as safe as anything and last but not least it is a pwm output device designed for slowing down fans. I believe a CC source may just run the fan at full speed.

Not sure what you read before typing but..
It was never suggested to use the dc power supply to run the fan, yu really should try reading

'..rather than suggesting you get one - though they are a great adjustable power supply for testing 12v stuff onboard.'

The reply was to -- 'The dimmer I linked to can be used to test things' -

Really a very bad choice for testing , much better to get a buck/boost with user definable current & voltage limits. Cheaper too.

As for 'I believe a CC source may just run the fan at full speed.', that's been shown on plot above already. Lower the current limit the voltage will of course decrease, how can it not???

Very noisy plot though, could well be the motor has no flyback diode, sticking meter on it doesn't show one. Though adding one doesn't seem to help the current fluctuation much - for PWM control probably maybe not a bad idea to add one anyway.



' Yourlink shows a device that requires connectors instead of simple screw terminals'

Can you really not see the screw terminals??

[Spot]

Also interested in GI's results, I have some large PC muffin fans recycled from work that I am thinking to use on the boat.


The boost-type supplies look scarier from a component count and RF standpoint to me. I suppose the layperson's test is to wire the fans and then power up all the radios looking for noise without the PWM modules, turning fans on and off, then trying everything again with the PWM modules.


Cona, nice graphing! I watched a guy use a Flex HF ham radio yesterday and my mind is still blown from the aspect of 'seeing' radio in terms of active bands and signal strength all at one time. My experience is more Luddite with buttons and knobs and needle meters...

[s/v Jedi]

Originally Posted by conachair

Not sure what you read before typing but..
It was never suggested to use the dc power supply to run the fan, yu really should try reading

'..rather than suggesting you get one - though they are a great adjustable power supply for testing 12v stuff onboard.'

The reply was to -- 'The dimmer I linked to can be used to test things' -

Really a very bad choice for testing , much better to get a buck/boost with user definable current & voltage limits. Cheaper too.

As for 'I believe a CC source may just run the fan at full speed.', that's been shown on plot above already. Lower the current limit the voltage will of course decrease, how can it not???

Very noisy plot though, could well be the motor has no flyback diode, sticking meter on it doesn't show one. Though adding one doesn't seem to help the current fluctuation much - for PWM control probably maybe not a bad idea to add one anyway.



' Yourlink shows a device that requires connectors instead of simple screw terminals'

Can you really not see the screw terminals??

Okay, you recommend to use a DC power supply for testing things aboard. I agree that is very handy, although I prefer a built bench supply that has CV as well as CC. But when you connect these fans to it, that does not test running them on PWM; it tests running them by limiting current, which lowers voltage... which is just a DC output, not pwm like the failed controls of these fans.

A high quality DC pwm dimmer on a 12V source still outputs 12V, it limits power transfer without lowering voltage, which is very different and as important a test tool as a dc power supply.

[noelex 77]

We had a couple of the simplier Caframo 12v 747 fans. I wanted to convert these to run off 24v and used a PWM converter. They work well.

The main aim was to convert the fans from 12v to 24v, but the advantage is that the fan speed is now infinitely adjustable rather than the normal two speeds. This is surprisingly useful as slightly adjusting the speed allows the perfect balance of noise and airflow while minimising the resonances in the blades and mounting structures.

BTW we purchased a Caframo Bora fan and were disappointed with the noise/airflow compared to the cheaper 747 model. I have seen the Sirocco on other boats but it hard to gauge the relative performance without the fans side by side. Has anyone owned both and can comment?

[conachair]

Originally Posted by s/v Jedi

Okay, you recommend to use a DC power supply for testing things aboard. I agree that is very handy, although I prefer a built bench supply that has CV as well as CC. But when you connect these fans to it, that does not test running them on PWM; it tests running them by limiting current, which lowers voltage... which is just a DC output, not pwm like the failed controls of these fans.

A high quality DC pwm dimmer on a 12V source still outputs 12V, it limits power transfer without lowering voltage, which is very different and as important a test tool as a dc power supply.

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.

it limits power transfer without lowering voltage,

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?'.

https://www.youtube.com/watch?v=-fii6G_ewdw

[a64pilot]

Originally Posted by noelex 77

We had a couple of the simplier Caframo 12v 747 fans. I wanted to convert these to run off 24v and used a PWM converter. They work well.

The main aim was to convert the fans from 12v to 24v, but the advantage is that the fan speed is now infinitely adjustable rather than the normal two speeds. This is surprisingly useful as slightly adjusting the speed allows the perfect balance of noise and airflow while minimising the resonances in the blades and mounting structures.

BTW we purchased a Caframo Bora fan and were disappointed with the noise/airflow compared to the cheaper 747 model. I have seen the Sirocco on other boats but it hard to gauge the relative performance without the fans side by side. Has anyone owned both and can comment?

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

[noelex 77]

Originally Posted by a64pilot

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Thanks.

That looks excellent.