Question Can I use a wall switch with a computer fan, like these to circuits?

Eximo

Titan
Ambassador
A bit confused. Are you wanting to run 12V through the wall switch? Seems to be what your drawings indicate.

Or do you mean to have the 12V supply switched on and off by the wall switch? That would be okay.

You can't have a power supply hooked up to a dimmer, no. Most power bricks are 100-240V, so when the dimmer drops below 100VAC it would shut off.
 

Ralston18

Titan
Moderator
I will say no.

However, what exactly are you trying to accomplish?

For example having the ability to manually turn the fans on or off?

Also, what is that 12 volt power adapter shown in the diagram?

If switches are a requirement then use a switch designed for electronics. Not a 120/240 volt wall switches and especially not if lighted or dimmer.
 
Mar 19, 2021
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A bit confused. Are you wanting to run 12V through the wall switch? Seems to be what your drawings indicate.

Or do you mean to have the 12V supply switched on and off by the wall switch? That would be okay.

You can't have a power supply hooked up to a dimmer, no. Most power bricks are 100-240V, so when the dimmer drops below 100VAC it would shut off.
Is the dimmer just a potentiometer? If so, I can use it to adjust fan speed. I am running 12V DC through the switch.
 

Eximo

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Ambassador
Depends on the dimmer. Older ones would be rheostats or variacs (which were bulky).

Modern ones are FET (Transistor) based and need the AC signal to regulate I believe. Not that familiar with the internals myself on that one. Plenty of schematics, and a few different ways to do it, but most I see use a DIAC and TRIAC.
 

InvalidError

Titan
Moderator
Depends on the dimmer. Older ones would be rheostats or variacs (which were bulky).
TRIAC dimmers have been around for quite a while, my mother has a 30+ years old one for her dining room. You wouldn't have a 500+W rheostat or variac in a standard electrical switch/outlet box.

Using a dimmer with a switching AC-DC power adapter isn't going to work particularly well, the harsh current spikes may cause the input capacitors to fail prematurely. The dimmer itself may also take offense to switching into a capacitive load.

Using a dimmer with a traditional iron core transformer could also be a little problematic due to the inductance possibly not allowing current through the TRIAC to rise fast enough to keep it on after the initial turn-on pulse fades out, an RC circuit in parallel with the inductor may be needed to smooth that over.
 

Eximo

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Ambassador
Yeah, I always think of the recent past as the 90s, always gets me that it is actually 2021 and thirty years old is well into the common household semi-conductor age.

Also used to older homes before I moved out. Built right on the cusp of the transistor age.
 

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