a bit OT: Dogs and modern TVs

A former colleague of mine had a dog that was not allowed to watch any David Attenborough or other wildlife programmes. Reason: every time the dog saw a bear it did a massive dump there and then.

Didn't have time to get to the woods then :-)

My mutt used to wag his tail when animals came on screen then run round to the back of the TV looking for them when they went off screen.

Dog whistles are often too high pitched for humans, but I don't know whather the sound would be loud or just unusual.

Modern TVs of course don't have the high-pitched line-scan frequency (that I could just about sense when I was much younger) that a dog might not like. Switch-mode power supply frequency?

nib

Its possible

Generally these days SMPS's are well over 50kHz tho

Its quite common to have lots of switching voltage converters littered over the digital PCBs after the main PSU as well. Even if the switching frequency is well out of the (dog's) audio range, there might be beat frequencies generated that are not.

So the dogs have access to their own beatbox, with moving images? <g>

On 05 Aug 2026, Davey wrote

But only in black and white?

Well, although they fail in the red and green departments, they are fine with blues and yellows.

Somewhat.Not sure about beat frequencies. You need distorion to down convert frequencies into the audible range.

On 06 Aug 2026, Davey wrote

So it's kind of like watching black and white telly with one of those plastic screens that you put in front of it in the 1960s/1970s to see it in "colour"?

(FWEW, I was aware of those at the time from magazine advertisments, but never saw one in real life.)

I saw one once, it said: "Best installed while a scene with grass and blue sky are showing". That really inspired confidence.

I have an (Android) smartphone app that shows the waterfall spectrum of the sounds picked up by the microphone. Maximum frequency is determined by FFT settings, looks like goes to 10 kHz on default settings, and 20 kHz or more on custom. ISTR bats echolocate even thinner than that, but use lower-frequency sounds to communicate. "Spectroid", free.

Might show the presence of high-frequncy sounds?

Thomas Prufer

subject to the (probably unknown) frequency response of the microphone ??

Yes, but most things don't 'fall off a cliff; outside the indicated spectrum

Of course. It's a very small microphone, so more likely to pick up high frequencies than a large one. (And: calibrated microphones are expensive!)

(Reading the comments on Spectroid, it seems that an older version allowed mic calibration...)

Thomas Prufer