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12v oscillating fan
#21
yea,most the speed controls were 2-3 amps which might get me by,might not,going for a larger fan moving slowly,ceiling fan like,gentle air movement on non hot days

have the fantastic fan box fan for direct air when it's hot,rv roof fan for mass air exchange and computer fan exhaust for gentle air exchange

thanks for digging through all those speed controls,give me a bunch of options and i go in to analyze everything mode,not fun
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  • heron (07-16-2020)
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#22
The oscillating brushed fan's two speeds, well it's likely you should not use the lower speed when using the 21KHZ PWM speed controller. It might work but waste a lot more wattage, or simply sound like its struggling, or it might change speeds on its own in an annoying manner.

Or it might not. Hard to say.

I am unsure why they even make sub 21khz motor speed controllers, at least for anything where a human can hear it. Definitely do not use one on a Fan within earshot, and even some LEDS will whine on PWM led dimmers with sub 18KHZ pwm dimmers/MSC's. I've used many PWM dimmers as fan speed controllers and as dimmers, and have removed them all, in favor of 150KHZ voltage buckers.

I've had 8 and 10 amp 21khz PWM MSC's, but like an idiot blew them all up reversing their input polarity, then used the 13khz LED dimmers and the fan whine was intolerable to the point I just quit even using the fan.
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  • heron (07-16-2020)
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#23
Thanks again Sternwake for all the good info you provide.

I just purchased 2 of the speed controllers that you linked to in post #20

https://www.ebay.com/itm/DC-Motor-Speed-...SwfpVZL2m2

I ordered it for a 12volt  12" 3 speed portable box fan.  I thought this would be the perfect thing for me as I've become more and more shaky and can no longer build these projects from scratch.  It's already set up with case, right size speed control knob and reversing polarity swithch for the load.

The box fan on its own pulls ~1.3 A at low speed and about 3.5A on high.  And after connecting the speed controller in line of course amperage is variable.  I've tried the controller on all 3 manual speeds of the fan and did not detect any problems for a limited 30 minute trial.  Fan temps and speeds remained constant.

I was a little concerned when I first connected the fan up.  Before connecting the fan, I measured the motor + and - connections on the controller.  I placed the polarity switch to have a positive voltage to the fan and then connected the fan and the blades were running in reverse.  I had to place the polarity switch to a negative voltage for blades to run in proper direction.  Since this portable fan has always run in one direction, I decided to keep it that way since the bushings are seated for that one direction.  It does seem to run ok in either direction but seemed slightly quieter in the original direction.

In the photo the bottom connector goes to power source.  Thank again can't beat it for $10.  Very comfortable airflow when only pulling .31A.  Parisitic draw is only about 15mA


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  • Blacktank (07-15-2020), sternwake (07-15-2020), heron (07-16-2020)
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#24
I've no experience with that specific PWM motor speed controller or those with reversing switches.

Strange that you had to put it in reverse to get it to run forwards, but perhaps no big deal. Most fan blades work poorly in reverse. Perhaps the outputs are just mislabelled?

Thanks for the report. Glad it works well for you. 3.5 amps is 1/3 of the PWM controller's rating and therefore should not heat up much and should last a long while. Good that is has a easy access fuse as well.

While in my experience reversing the polarity on a brushless fan, or LED light, it just does not spin up/light up, and no damage occurs, it is likely best to test + and - output beforehand.

I'll assume you used a DMM to measure the 15mA draw since the Wattmeter does not read that low, and some of them seem inaccurate under 500mA/0.5 amps.

The two lower speeds on the fan itself likely use resistors to lower voltage and slow the fan rpm, which reduces efficiency. It would be hard to tell with out a tachometer but it is likely most efficient to have the fan's own switch on highest speed and use the PWM controller for speed control.

I have a 120vAC router speed controller of unknown khz, that I have used on 120vac box fans. On one older fan it seemed to work fine on any of the fan's own speeds, but a newer box fan it whines badly, sounding sick. So I do not use it. The older fan shit the bed, but I do not know if the PWM controller contributed to its failure, or the motor just burnt up from too much cedar and fiberglass dust compaction inside motor itself, and/or age.
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  • heron (07-16-2020)
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#25
Yes mislabelling on the output is the only thing that made any sense to me also about having to reverse the voltage.  However It is reversed from the fans original wiring.  I'm gonna have to think on this more.  But hea IT WORKS.  The parasitic draw was just a guesstimate taken from the wattmeter.  The reversing polarity switch is a 3 position switch (middle position off)  I could check closer with dmm but seems minimal.

I didn't think about the 3 position fan switch being a resistive load.  When I have time I'll check the efficiency.  But as of now I'm so happy with it not that concerned.  I mean my solar controller has a 200 mA parisitic draw overnight Sad .  I do have a breaker/sw to the battery for the solar controller when I get irritated enough.  Big Grin

I remember those 120 VAC triac speed controllers from tech school.  Good efficiency at the time.  Damn that was 40 years ago.
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  • heron (07-16-2020)
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#26
Make sure the controller doesn't get panel voltage when the battery is disconnected though .
Stay Tuned
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  • Gapper2 (07-16-2020), heron (07-16-2020)
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#27
Thanks Popeye,  I didn't even think about that but I am in the habit of disconnecting the panels before shutting down everything.  Damn one more thing to remember.  Running out of room.    Big Grin
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  • heron (07-16-2020)
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#28
Well I just wired up my second controller with powerpole connectors and also works like a champ.

Mystery of the negative voltage solvied!!

Blush Blush Blush Blush 

poor light and eyesight + wrong reading glasses =  misread dmm screen


Internal fuse is only .5 ohm fastblow.  Guess that's good for the controllers sake.

 After rereading the thread Blacktank,  I believe my fan is very much like yours.  Puts out high volume of air when required.  A little on the noisy side with or without the controller but I also like a little air movement all year round and nice now to select very low amp draw and air flow.
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  • heron (07-16-2020)
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#29
A 0.5 amp fuse on a controller rated for 10 amps?

My early fan speed controls had a couple of set speeds, 3v 4.5v 7v 9v and 12v. They were universal power supplies that slid into ciggy receptacles and limited to 2 amps output. Basically I don't employ any fans which cannot consume more than that now, when cranked to their higher speeds.

I don't know how I handled those limited options, especially since 3v would not turn any 12v fan, and battery voltage might be 14.7v, but 12v output max..... absolutely Intolerable!!! Wink, but of course any fan is better than no fan.

I've got potentiometers everywhere, for every fan, and they can output just 0.3v less of input voltage, some within 0.17v using my 5 amp 150khz xl4015 voltage bucker as speed control method. These buckers are also on every one of my led lights as a dimmer too.

I actually only employ one PWM speed controller in my rig, and that is on my Van's Blower motor. But this stock blower fan is the least efficient in terms of air moved for amperage consumed, but it beats the pants off of having only low medium high and turbo options of the stock resistor based speed control which only works with the ignition key turned to ON.

I used to employ PWM led dimmers as well, but these as they aged started having the LEDs flicker. All but one has been replaced with the xl4015/xl4005 voltage bucker. I've also used these dimmers to control fans, but they would whine so badly i found it intolerable and would just use fan at highest speed in order to not hear that contemptible whining noise.

A lot of the computer fans have 4 wires, the 4th wire being a PWM signal wire, that the computer's motherboard can use to control fan speed, as opposed to a PWM supply on the + and -. NOt only does controlling fan speed on this 4th wire consume more wattage, slightly, every fan that I controlled via this method, failed. That 4'th wire's contacts within the connector, seemed to dissolve either at the connector or where it joined the fans circuit board.

I've only a few unexplained non stupidity induced faiilures of the voltage buckers. I've had a few fans fail because of corrosion where the wires enter the circuit board on the hub, or nearby. I now clean all these and cover with Amazing goop to protect. Often impeller removal is required for access in order to 'harden' the circuit board.

I've not opened any brushed fans lately, but the ones I did have no circuit board to corrode, just brushes to get stuck or wear out.
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  • Gapper2 (07-16-2020)
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#30
Thanks for questioning what I type.   Blush Blush Blush( My bad  Once again I make mistakes .  Yes it is a 10 amp fuse.  Working in this heat and humidity is baking what's left of the few noodles I got left.  Smile

I'm such a newbie I tried to research the kind of dc motor the fan has.  And gave up and guessed it was one with brushes.  I did't know that a pwm controller would work with this type of motor.  I have pwm fans also so I was willing to try.  Thanks again for the help.
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  • heron (07-16-2020)
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