Caframo fan speed control

[GILow]

Hi all,

I recently found four very clean and tidy Caframo fans in the bin at the marina. I grabbed them, thinking spares for my existing Caframo Sirrocco II fans.

It turns out that all have perfectly functioning fan motors, but all have dead control boards. The cause of death for each seems varied, switch failures, logic failures and power supply failures.

I could actually use a few more fans on board, so, I am thinking of tossing the control boards and replacing them with nice cheap PWM dc motor controllers from EBay.

Has anyone tried this? It should work, but I wondered if the PWM approach might create strange harmonics or motor heating. I’ve seen both over the years with these sorts of small motors.

Matt

[Jim Cate]

Haven't tried it with Calframo fans, but have with a muffin fan used to force the draft on our diesel heater... and it works ok in that application. Can't see that any great harm can come from doing the experiment, beyond the cost of the PWMs. After all, that's likely what the OEM was doing with those faulty PC boards, isn't it?

Jim

[wsmurdoch]

I have a Caframo Bora with a failed motor speed control. I straight wired the motor making it run on high. Then, in its supply I added a double pole double throw on-off-on switch. Power enters the switch at one center connection and leaves from the other. There is a jumper between the two upper contacts and a resistor between the two lower contacts. In one on position the fan runs at full speed. In the other on position the fan runs at a lower speed.

I suspect that the usual 12V LED dimmers would work just as well and be cheaper. https://smile.amazon.com/s?k=Hiletgo...ref=nb_sb_noss

Bill

[MartinR]

Originally Posted by GILow

Hi all,

I recently found four very clean and tidy Caframo fans in the bin at the marina. I grabbed them, thinking spares for my existing Caframo Sirrocco II fans.

It turns out that all have perfectly functioning fan motors, but all have dead control boards. The cause of death for each seems varied, switch failures, logic failures and power supply failures.

I could actually use a few more fans on board, so, I am thinking of tossing the control boards and replacing them with nice cheap PWM dc motor controllers from EBay.

Has anyone tried this? It should work, but I wondered if the PWM approach might create strange harmonics or motor heating. I’ve seen both over the years with these sorts of small motors.

Matt

This should work without a problem. It is a better way to go than the resistor/switch, mostly because you save energy when running the fan at low speeds.

[fivecapes]

Originally Posted by GILow

...but I wondered if the PWM approach might create strange harmonics or motor heating...

If I'm not mistaken the motor has to have a 4th PWM signal wire for PWM to work.

[GILow]

Originally Posted by fivecapes

If I'm not mistaken the motor has to have a 4th PWM signal wire for PWM to work.

I think you may be thinking of a stepper motor. Or maybe some kind of motor that is controlled by a PWM signal..?

But there are simple circuits on eBay that you connect directly to a standard dc motor that use PWM to control the amount of power supplied to the motor, and hence the speed.

[GILow]

Originally Posted by MartinR

This should work without a problem. It is a better way to go than the resistor/switch, mostly because you save energy when running the fan at low speeds.

Yes, particularly relevant as I rarely, if ever, run these fans at full speed. They are reasonably quiet on the first two speed settings, but at full speed I find them a bit noisey.

[GILow]

Originally Posted by wsmurdoch

I have a Caframo Bora with a failed motor speed control. I straight wired the motor making it run on high. Then, in its supply I added a double pole double throw on-off-on switch. Power enters the switch at one center connection and leaves from the other. There is a jumper between the two upper contacts and a resistor between the two lower contacts. In one on position the fan runs at full speed. In the other on position the fan runs at a lower speed.

I suspect that the usual 12V LED dimmers would work just as well and be cheaper. https://smile.amazon.com/s?k=Hiletgo...ref=nb_sb_noss

Bill

Didn’t know about those dimmers, but for the record, the PWM dc motor controllers for low current motors like these are even cheaper still, AU$4 for the sort I’ve been looking at.

[GILow]

Originally Posted by Jim Cate

Haven't tried it with Calframo fans, but have with a muffin fan used to force the draft on our diesel heater... and it works ok in that application. Can't see that any great harm can come from doing the experiment, beyond the cost of the PWMs. After all, that's likely what the OEM was doing with those faulty PC boards, isn't it?

Jim

Good point, that’s probably what they were doing. The board was a bit hard to decipher, it has a bit on it between speed control, power supply and timer controls.

But so far nobody has tried it and failed, so if there are no cautions raised in the next few days I’ll go ahead and order the controllers.

The problem is, the postage is more than the circuits themselves, so I’d like to order at least four, plus maybe a couple of others in case my current fan controllers fail too. So it will be an outlay of $30. Not a lot, given the value of the fans, but I’d like it to be money well spent.

[Fore and Aft]

GiLow maybe that could be a new thread “Marina Dumpster finds” My best dumpster find found me courteous of the marina manager who came knocking on our hull. The marina manager had just stopped a guy from dumping a trolley full of goodies into the dumpster and was told there was plenty more to come from the guy. It turned out the guy had just brought a 45 foot power boat and wanted all the “old stuff of it!” So the marina manager and I happily stripped the boat for him.
Cheers

[GILow]

Originally Posted by Fore and Aft

GiLow maybe that could be a new thread “Marina Dumpster finds” My best dumpster find found me courteous of the marina manager who came knocking on our hull. The marina manager had just stopped a guy from dumping a trolley full of goodies into the dumpster and was told there was plenty more to come from the guy. It turned out the guy had just brought a 45 foot power boat and wanted all the “old stuff of it!” So the marina manager and I happily stripped the boat for him.

Cheers

It would be a good thread.

I confess, I always “look before I toss”, on the logic that I don’t want my stuff to cover anything good.

These fans are probably at the better end of what I’ve found so far, though I am trying to remember some other good stuff that I know I’ve found in the past.

Any of the power boat stuff you found still doing active duty for you?

[s/v Jedi]

I recommend you buy this and try it. If it works, you can find much cheaper ones for actual installs.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[GILow]

Originally Posted by s/v Jedi

I recommend you buy this and try it. If it works, you can find much cheaper ones for actual installs.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

Sorry, I must be missing something.

What is the logical rationale for buying something that is almost ten times the price?

I mean, if it works, great, but it doesn’t prove the cheap ones work.

Normally you’d do proof of concept with a cheap one, then if it didn’t work, based on your observations of the mode of failure, you might buy something more expensive.

What am I missing?

[conachair]

Just had a play on a buck/boost CC CV , just cos it was sitting there plugged up rather than suggesting you get one - though they are a great adjustable power supply for testing 12v stuff onboard.

https://www.amazon.co.uk/UIOTEC-Cons...tronics&sr=1-1

So seemed to work just fine, current fluctuating a bit even though it's a constant current or constant voltage output. First half o the plot is constant voltage, just under 8v, then about 11v then 12.5v after that constant current at 0.5A.
So you should be able to get a cheap little buck/boost off ebay to do the job. Might need to keep an eye on RF noise though, some of the cheap ones have little filtering and can make a mess on the radio waves.

[s/v Jedi]

Originally Posted by GILow

Sorry, I must be missing something.

What is the logical rationale for buying something that is almost ten times the price?

I mean, if it works, great, but it doesn’t prove the cheap ones work.

Normally you’d do proof of concept with a cheap one, then if it didn’t work, based on your observations of the mode of failure, you might buy something more expensive.

What am I missing?

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.