It's hot in here so I have a fan on by my side a lot of the time. Its minimum speed is too strong so I get tired of it after some time and I turn it off. Then I get hot again and I turn it on again later. In summary, it's turned on and off multiple times a day.

About two or three out of every ten times I turn it on or off, my mouse and keyboard stop working.

My mouse and keyboard share a USB hub that is connected to the computer. It is not a powered hub, so it's not connected to the mains. It's just connected to the computer's USB port.

So when I turn on/off the fan and the mouse and keyboard stop responding, the fix is to unplug them from the hub and plug them in again. That fix works every time.

My computer is connected to a UPS, but the fan is not. However, the UPS and the fan share the same power outlet extension. I like to believe that the UPS between the computer and the extension is enough separation to prevent the fan from interfering with the computer, but that is obviously not true.

So my question is, can I prevent this problem from occurring?

Maybe I could just get a separate extension for the fan, but I'm curious about people with knowledge of electrical installations might have to say about this. They're probably going to talk about grounding. Sigh. Proper grounding is not very common in my country...

TIA

Having to keep switching on & off is most likely because it is too near to you, if you move it further away, you should be able to leave it running continuously.

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I agree with one possibility that the fan power wires could be to close.

Power wiring that runs parallel to your USB wiring if to close could be causing interference.

Hi,

I personally would move the fan power source away from the same source as your computer. The UPS should filter any noise but that too could be passed depending on the filter design. The on/off cycle of the fan could be spiking signals to the system. Large inductive loads nearby can be an EMI issue when cycling to a poor filter source for your systems.

Either move the fan to a different power source or provide better filtering of your power. Isolate the Computer system from external injection of noise (EMI) by a better UPS or put yourself in a Faraday cage.

Hope this helps.

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The evidence shows that this is a problem. Seems unlikely. The USB HUB is not plugged in to A/C power, just the computer.

Silly question, I have somewhat the same setup, a fan and it is a large standing fan about 18" in diameter on a pole and pedestal. Same thing, it can overdo things, so like what Fatmac suggested I moved it back and then I can keep it on longer or all the time without it being a problem.

BUT ... this new whiz-bangy fan, has a remote.

Any chance you're using a remote, and THAT is what may be causing this?

Otherwise, the electrical wiring in your domicile seems to be transferring large transients across it. I wonder if you had like a filter or a surge suppressor in line there where it would avoid this. Seemingly not since I can't imagine a UPS that doesn't have some level of isolation and surge suppression included.

If you think about it, this is occurring to keyboard and mouse, those likely are Bluetooth to the computer. Are they the same Bluetooth, or are the entirely independent dongles? Maybe experiment and plug the mouse directly into the PC, shut/power the fan and see what occurs, and then experiment with the keyboard, or both if its all one dongle. Maybe the USB HUB is the thing taking the hit?

Any electrical equipment will cause a transient signal when switching off or on, and sometimes that transient can be very noisy, one might used to opine that older, more powerful equipment would be the noisy things, but these days with quality control and the fact that a fan motor is cheap, not intended to last forever, even though it is light load, it could be noisy also. Got a second fan of a different type? Try that, all experimentation basically.

Or, try using an extension cord to plug the fan in farther away. Thing is, if the wiring has the outlets on the same circuit, then you may still see this, but also maybe the transient of switching may be reduced with greater distance. I wonder if speed changes to the fan could cause this, or if you do that and bring the fan closer to your PC when you do. Not saying it also could not be some signals interfering with Bluetooth or whatever your mouse and keyboard use to communicate, but likely not those signals are usually in the same frequencies as your WiFi, 2.4 GHz.

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Hi,

Signal injection(noise) can be a hard thing to track without proper diagnostic equipment. Not everyone can afford a spectrum analyzer to look for problem signals. If the USB hub is external(potential injection point) then of course a signal can be introduced from external noise source. A Pi filter could be used to reject the noise if you know the signal noise frequency but a general suppressor may work but that too would need to be setup to the particular frequencies band. This could be used at the system power source.

I agree that the OP should move the fan from the shared power source but that could still inject into other branches of power. Most cheap fans that use a simple motor (Universal Motor) that can create a lot of EMI from the brushes on the commutator. Switching on/off just introduces more noise spikes of energy.

If your fan uses a synchronous electric motor then noise generation would only be from the on/off since no commutation is used.

Best would be to rid yourself of that fan period to remove that noise generator.

Hope this helps.

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"Proper grounding is not very common in my country..." This is really part of an overall electrical issue with many countries. There are so many unknowns here it isn't possible to guess them all. A power quality meter and maybe a emi/rfi meter would be needed along with a Volt meter. I get into arguments in the USA with idiots that make things unsafe and they don't get it.

Well, at least there are two other issues to look at if you don't want to think safety.

One is the EMI/RFI this fan may be producing. Move it far away maybe for test. Find different fan and see if it also fails.
Two is a quality issue of the UPS. A good ups can correct for all sorts of electrical issues. I doubt this one is such.

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Hi,

What type of shielding is used for a motor is another point. Most cheap fan units are constructed from plastic for chassis with no regard for proper metal shield to keep noise emission lower. Proper grounding will insure more for safety than shield of the noise when a non-metal chasiss is used.. Signal injection can be limited by metal shields but signals via ground would be minuscule or none at all. Split ground plane(differential between chassis and circuit) shield will limit the injection/radiation of noise some but no large radiated signal noise from RFI. Some shielding is constructed with thin sheet metal or even simple wire mesh to limit radiations.

One should remember that the power cords can be a antenna an cause radiation of noise by picking up noise and distributing throughout via radiation. Pathways for the power source cords should be a point of awareness so as not to maximize or contribute to the introduction of radiated noise. You can purchase power line filters for both the input and output power lines. Inline filters may help with signal noise mitigation but the best defense is find the source of the noise signal.

Hope this helps.

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To prove or disprove EMI, and if it is a laptop, unplug it from the wall jack and run on battery. Or unplug the UPS and run off that battery.