Good day folks. What I'm trying to achieve may seem pretty simple and although I found lots of discussions on the topic, it's hard for me to settle on a definitive answer, so I thought I'd ask for more opinions.
I have a small inline duct fan which looks like this, which I want to slow down, the reason being overall noise. I have no idea what type of motor this is, because I can't exactly take it apart to inspect it without ruining it, but perhaps we can work it out by examining its behavior.
Two things I've tried: a variac and a cheap light dimmer (triac+diac inside of it). The variac worked great: as I lowered the voltage, the fan slowed down and didn't give off any immediate signs that I shouldn't be doing what I was doing.
The dimmer was less than ideal: other than the fact that the motor slowed down considerably as soon as I moved the slider a small fraction, which made the slider virtually useless, the motor buzzed quite noticeably and I was afraid to let it run like this for too long, fearing the triac might pop.
I also have one of these that I could try, but I reckon it's the same exact thing as the dimmer I just tried, since I see the same exact components, with the exception of the inductor. The light dimmer also has a large inductor, but other than that, they seem virtually identical: diac, triac, potentiometer, capacitor. I heard about different kinds of dimmers and stuff like "phase angle control", but wouldn't know how to measure and analyze any of this stuff without a scope, which I don't have. I think all garden-variety hardware store dimmers will be like this and wouldn't be much better...
Based on these observations, I believe we're dealing with a shaded pole motor ? The variac (transformer) solution seemed to work the best, but I'm definitely not going to dedicate a big variac to this one sole use, neither am I willing to invest in VFDs to drive a small motor, so I think I'll have to compromise.....
I have a small inline duct fan which looks like this, which I want to slow down, the reason being overall noise. I have no idea what type of motor this is, because I can't exactly take it apart to inspect it without ruining it, but perhaps we can work it out by examining its behavior.
Two things I've tried: a variac and a cheap light dimmer (triac+diac inside of it). The variac worked great: as I lowered the voltage, the fan slowed down and didn't give off any immediate signs that I shouldn't be doing what I was doing.
The dimmer was less than ideal: other than the fact that the motor slowed down considerably as soon as I moved the slider a small fraction, which made the slider virtually useless, the motor buzzed quite noticeably and I was afraid to let it run like this for too long, fearing the triac might pop.
I also have one of these that I could try, but I reckon it's the same exact thing as the dimmer I just tried, since I see the same exact components, with the exception of the inductor. The light dimmer also has a large inductor, but other than that, they seem virtually identical: diac, triac, potentiometer, capacitor. I heard about different kinds of dimmers and stuff like "phase angle control", but wouldn't know how to measure and analyze any of this stuff without a scope, which I don't have. I think all garden-variety hardware store dimmers will be like this and wouldn't be much better...
Based on these observations, I believe we're dealing with a shaded pole motor ? The variac (transformer) solution seemed to work the best, but I'm definitely not going to dedicate a big variac to this one sole use, neither am I willing to invest in VFDs to drive a small motor, so I think I'll have to compromise.....
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