Variable speed fan control

[LWM723]

Would a standard 110v light dimmer switch wired inline with a standard 12 volt PC fan work?

[AbydosOne]

1 minute ago, LWM723 said:

Would a standard 110v light dimmer switch wired inline with a standard 12 volt PC fan work?

No, AC dimmers work on a different principle from DC variable sources.

[LWM723]

@AbvdosOne How so ir's just a rheostat doesn't matter whether ir's ac or dc?

[AbydosOne]

26 minutes ago, LWM723 said:

@AbvdosOne How so ir's just a rheostat doesn't matter whether ir's ac or dc?

AC dimmers haven't been rheostats in decades. Rheostats are terribly inefficient (and borderline dangerous, thermally) for non-industrial applications.

 

Everything AC is solid-state now days. Dimmers chop the AC waveform at a specific point in each cycle to get the desired power output. At absolute minimum, the control circuitry inside is expecting to be powered from AC and not DC, so it probably wouldn't even start. Also, the control circuit is looking for the zero crossing each half cycle to synchronize the chopping, so DC would probably confuse it.

[LWM723]

@AbvdosOne NOT true, and your explanation is misleading hogwash. I just opened a dimmer switch and lo and behold there is a rheostat in it an NO "circuitry". How did you manage to come up with this BS. And I hooked it up to a 12v PC fan and it works! Learn what your talking about before you post and look stupid.

[AbydosOne]

1 minute ago, LWM723 said:

@AbvdosOne NOT true, and your explanation is misleading hogwash. I just opened a dimmer switch and lo and behold there is a rheostat in it an NO "circuitry". How did you manage to come up with this BS. And I hooked it up to a 12v PC fan and it works! Learn what your talking about before you post and look stupid.

1. Spell my name right if you actually want to tag me.
2. Read the Wikipedia article.
3. I told you what's true of modern housing dimmer switches; I have seen AC rheostats in (extremely) cheap lamp dimmer adapters, but they waste all the energy not sent to the output device (in the form of a dangerous amount of heat). Your failure to include a reference to or picture of the part you're (ab)using is not my fault. I tried my best, sorry.
4. I know quite well what I'm talking about, thank you, which is why I bothered to try and help you (I literally have a degree in EE).

[LWM723]

@AbydosOne Sorry I spelt your name wrong. This is is a new, just purchased, in-wall dimmer switch (replaces a standard light switch) and the rest of what I said still applies.

[AbydosOne]

Just now, LWM723 said:

This is is a new, just purchased, in-wall dimmer switch

Mind sharing a picture? I don't doubt you at this point, I'm just curious now.

 

2 minutes ago, LWM723 said:

rest of what I said still applies

You could still be a little nicer with the "I think you're wrong, here's what I see".

[akio123008]

27 minutes ago, LWM723 said:

@AbvdosOne NOT true

No modern light dimmer (of any reasonable power output) is a rheostat.

 

[LWM723]

@akio123008 

rheostat-  "an electrical instrument used to control a current by varying the resistance"

[akio123008]

1 minute ago, LWM723 said:

@akio123008 

rheostat-  "an electrical instrument used to control a current by varying the resistance"

You don't have to tell me what a rheostat is.

[LWM723]

@akio123008 Then what do you call the rotary switch inside this light dimmer rhat makes the light brighter and dimmer. By the way, this switch is for incandescent bulbs.

[Dr_Whom]

Nobody:

 

People on the Internet: Hey I know I asked for help with this thing but I was JK I actually know everything about it and you're all wrong and stupid.

 

 

Why do I feel like this is 80% of help threads? 

[AbydosOne]

12 minutes ago, LWM723 said:

@akio123008 Then what do you call the rotary switch inside this light dimmer rhat makes the light brighter and dimmer. By the way, this switch is for incandescent bulbs.

Did you disassemble the switch and pull the control rheostat out? Or are you connecting to the screw terminals on the outside?

 

(brrowed from https://sound-au.com/project157.htm)

 

There is still a controller rheostat in a solid-state dimmer, I'm not disagreeing with that.

[LWM723]

@akio123008

Rheostat, adjustable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors.

 

@AbydosOne I pulled the rheostat out of the enclosure as I want to mount it without the enclosure. As for a photo, may take a couple weeks to develop the film

 

@AbydosOne  The only things inside the mounting enclosure were the rheostat and what looks like a large resistor, assuming it's a electrical AC noise filter (not needed for 12v DC).

[akio123008]

38 minutes ago, LWM723 said:

Rheostat, adjustable resistor used in applications that require the adjustment of current or the varying of resistance in an electric circuit. The rheostat can adjust generator characteristics, dim lights, and start or control the speed of motors.

I told you I know what a rheostat is. However, you appear to think that a rheostat is the only way to control the current in a circuit. A rheostat controls output power indeed, but not all devices that control power in a circuit are rheostats.

 

A rheostat is a very inefficient and crappy way of controlling power in a circuit. Most modern light dimmers don't use rheostats to control the output power.

 

42 minutes ago, AbydosOne said:

There is still a controller rheostat in a solid-state dimmer, I'm not disagreeing with that.

The rheostat mentioned here is purely for control, this rheostat isn't part of the power circuit.

[akio123008]

57 minutes ago, LWM723 said:

@akio123008 Then what do you call the rotary switch inside this light dimmer rhat makes the light brighter and dimmer. By the way, this switch is for incandescent bulbs.

The rotary "switch" may be a rheostat, but the actual part of the device that controls the output power isn't one. At least in a design that isn't from the 30s.

[Morrie Sells Wigs]

15 minutes ago, LWM723 said:

@AbydosOne  The only things inside the mounting enclosure were the rheostat and what looks like a large resistor, assuming it's a electrical AC noise filter (not needed for 12v DC).

You seem very capable and well informed.

 

It seems like you didn't actually need anyone's help.

[LWM723]

@akio123008 Read the post, this is a newly purchased switch. THERE IS ONLY A RHEOSTAT INSIDE THE ENCLOSURE NOTHING ELSE!

[LWM723]

@akio123008  If you don't believe it buy one and open it up, they're only about $5.

[leadeater]

Locked, this discussion isn't going anywhere productive anymore and working solution looks to have been made.