Fly Repeller Fan Interferes with TV

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MurrayM

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#318399 14-Jan-2025 11:39

I've recently bought one of these fly repeller fans on Aliexpress:

However I've noticed that it interferes with my TV. With the fan turned on I get the sound cutting in and out and blocks of colour appearing in the picture and also freezing of the picture. With the fan off the TV is fine. This is when I'm watching live terrestrial TV, streaming is fine with the fan turned on. Happens on both TV 1 and TV 3. Distance from the TV to the dining room table (it's all one big open-plan room) is about 6 metres. The table is slightly above the height of the TV, and I've noticed that if I lift the fan up about 600mm or more from the centre of the table then the interference goes away. I can't really relocate the TV or the dining room table.

I've opened the fan up and it's basically just a battery compartment in the base and a small motor attached to the fan blades at the top, with two wires running from the motor to the battery compartment. The top knob of the fan pulls off and you can see the motor attached to the knob and the blades. There's a bit of space in the top compartment where the motor sits.

Any suggestions for how I might stop the TV interference? Maybe wrap the motor in something to shield it?

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#3331286 14-Jan-2025 11:42

should be a small ceramic capacitor across the motor to shunt out the interference caused by the brushes arcing. Left off because it didn't need to meet any RF tests as it was being exported. Find some junk electronics and pillage any ceramic cap and put it across the terminals and it will be fine. Value not really important for this.

Richard rich.ms

MurrayM

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#3331294 14-Jan-2025 11:57

richms:

should be a small ceramic capacitor across the motor to shunt out the interference caused by the brushes arcing. Left off because it didn't need to meet any RF tests as it was being exported. Find some junk electronics and pillage any ceramic cap and put it across the terminals and it will be fine. Value not really important for this.

Excellent!

I found the following in my components drawer:

Which would you recommend?

mkissin

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#3331432 14-Jan-2025 13:45

I'd go with the 104, because 100nF is everybody's favorite value!

Connect it as close to the motor terminals as you can, with the legs as short as possibe.

MadEngineer

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#3331453 14-Jan-2025 14:37

Is that via dish or terrestrial? Also can I have a link to buy the same? Asking for a mate who wants to annoy his son when he’s watched too much tv.

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MurrayM

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#3331454 14-Jan-2025 14:44

MadEngineer: Is that via dish or terrestrial? Also can I have a link to buy the same? Asking for a mate who wants to annoy his son when he’s watched too much tv.

Terrestrial.

Here's the one I bought: https://www.aliexpress.com/item/1005007706855177.html?spm=a2g0o.order_list.order_list_main.10.c27e1802MMLZjw That link says it's $12 but I actually only paid $6 because I used Aliexpress' Today's Deals. After it arrived I actually found what looks to be the identical product in my local Dollar Shop for $12.

MurrayM

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#3331783 15-Jan-2025 13:52

So after finally hunting down my old soldering iron, I found some time to solder the capacitor on to the motor's terminals. Looks like this:

When testing that I found a slight improvement in the TV interference, but still enough of it to cause the other half to complain.

I wondered if maybe my soldering skills weren't good enough (very likely) or that the capacitor was faulty (less likely). I unsoldered it and did a continuity test between the two legs and got no continuity (which I assume is what's to be expected?). I soldered it back in and did a continuity test between the legs and this time got continuity. So from this little test I think my soldering is ok?

Anything else I can test? I cut the legs to make them shorter but maybe they're still not short enough?

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mkissin

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#3331810 15-Jan-2025 14:51

That looks fine to me. Not perfect but you're unlikely to make significant improvements by shortening the legs. Wouldn't hurt to try if you want, of course. Try to bend them out right at the case, as close as you can without cracking it.

You probably just have a really sweet wideband noise generator there. You could try wrapping the entire thing in foil and/or moving it as far away from the TV as practical.

elpenguino

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#3331816 15-Jan-2025 15:02

You may have sub-optimal signal strength in your aerial system.

You may improve things by using better quality (i.e. better shielded) coax cable in your aerial cables.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

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#3331822 15-Jan-2025 15:09

elpenguino:

You may have sub-optimal signal strength in your aerial system.

This is a good point. It's quite possible that you have barely-acceptable signal strength at your TV. Your aerial may be misaligned, the cable could be damaged (or just suck) or the aerial could be too small.

k1w1k1d

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#3331824 15-Jan-2025 15:22

A few suggestions don't know if they will make any difference.

Could try twisting the wires from the battery to the motor.

Add a second capacitor.

Add a resistor across the motor terminals.

Does your tv have any means of testing signal strength/quality etc in its settings?

dafman

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#3331825 15-Jan-2025 15:23

If you can't be bothered waiting for Ali:

https://www.mitre10.co.nz/shop/shoo-away-fly-repellent-device-black/p/296360

https://www.briscoes.co.nz/search2/?q=shooaway

We use these around summer food, work a treat

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MurrayM

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#3331827 15-Jan-2025 15:28

dafman:

If you can't be bothered waiting for Ali:

https://www.mitre10.co.nz/shop/shoo-away-fly-repellent-device-black/p/296360

https://www.briscoes.co.nz/search2/?q=shooaway

We use these around summer food, work a treat

Yeah, those were the ones I saw and thought to myself "Gee that's a bit expensive for what it is, I'm sure I can find something similar at a cheaper price on Aliexpress". Now I know why my cheapie knockoff was so cheap! :-)

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#3331834 15-Jan-2025 15:55

elpenguino:

You may have sub-optimal signal strength in your aerial system.

You may improve things by using better quality (i.e. better shielded) coax cable in your aerial cables.

I tried swapping the coax cable from the wall to the TV with two other coax cables I had, unfortunately there was no improvement. It's possible the cable between the wall and the aerial isn't very good, but I'm not going to investigate that as it would obviously be a big job. I'm also not too sure about the aerial itself, we're in a rental and my other half doesn't like me climbing on the roof.

MurrayM

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#3331836 15-Jan-2025 16:02

k1w1k1d:

Does your tv have any means of testing signal strength/quality etc in its settings?

Yes it does. It has Signal Strength and Signal Quality numbers (not sure what the difference is). With the fan turned off the Signal Strength is 91 and the Signal Quality is 100. With the fan turned on the Signal Strength remains at 91 but the Signal Quality fluctuates anywhere between 45 and 90.

elpenguino

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#3331846 15-Jan-2025 16:26

MurrayM:

k1w1k1d:

Does your tv have any means of testing signal strength/quality etc in its settings?

Yes it does. It has Signal Strength and Signal Quality numbers (not sure what the difference is). With the fan turned off the Signal Strength is 91 and the Signal Quality is 100. With the fan turned on the Signal Strength remains at 91 but the Signal Quality fluctuates anywhere between 45 and 90.

Hmm. Sorry, that does point towards an adequate aerial but poorly shielded coax.

You might have to work on mitigation strategies. And there's not much good on telly these days anyway.

Most of the posters in this thread are just like chimpanzees on MDMA, full of feelings of bonhomie, joy, and optimism. Fred99 8/4/21

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