Exploring an ultrasonic pest repeller

Yeah pretty much. I even added a button input to stop the frequency sweep where it is as long as its pressed and a button to manually start over. Building a repellant device out of this should be pretty easy.

Leon Schutte

Sounds interesting. By "My implementation is not the best" you mean that you cobbled an initial version together and it worked to do the job. That's about 99% of the software I write.

Big Clive

I actually have written a program that sweeps through the frequencies because i needed a frequency generator to check the resonance frequency of 125khz transponders. I actually know what they have done. Its very likely a lookup table. Also to do smaller steps they did the tradeoff with not always symetric pulse width. If you like i can send you my little program. Its written for the 16f628a and when i remember right it can sweep from 56kHz up to 238khz. It can easily be modified though to start at a lower frequency. My implementation is not the best but it did the job at the time

Leon Schutte

Clive, might be worth explaining how you connect your scope to monitor signals in a situation like this. Technically, connecting the ground of your scope probe to the "0V rail" in this circuit could short out diodes in the bridge rectifier and attaching ground to any live point will result in a very nasty surprise. I always use an isolating transformer when probing equipment at mains potential, though I've heard you can lift the earth in the mains plug for pseudo-safety. This might automatically be the case in countries which use 2-pin mains plugs but not in the UK..

Gordo

Interesting stuff!

Todd Sharp

I built one of those a while ago. It did confirm neighbourhood bats in Glasgow. The detector feeds a very high gain amplifier that clips it into a square wave that then drives the counter. I did toy with adding a 4040 between the chip output and drive transistor on this plug to make the output audible. But the scope seemed a better idea.

Big Clive

http://batdetector.freevar.com/ - this what I used. hope it is of some help.

Rik Kershaw-Moore

I like that micro controllers are literally black boxes.

MrTridac

Do you have a schematic for the detector? I tested mine with my mobile, but that's limited to like 20khz I believe. The other problem i had was power as the deployed location didn't get much sunlight so my solar supply didn't last long.

Todd Sharp

I kind of did the reverse and built a bath detector first then built an simple ultrasonic sound emitter to test the detector works - dunno if that helps

Rik Kershaw-Moore

I had heard that rodents, particularly rats are change phobic, so you have to keep changing the pattern of the "sound", eg continuous / pulsed and change the pattern at least every day to annoy the rats to go look for a less annoying place to forage.

Dr Andy Hill

Lidl currently have a pest repeller, a PIR operated hose pipe sprayer, ideal for dealing with Jehovah's Witnesses :)

+1 😎

Apple has been phasing out that "breathing" status LED. None of the their desktop Macs have used them for years and now they've started phasing it out on their laptops as well.

tim1724

I never get tired of that!

Circuitmike

I suspect strongly that the placebo effect is a huge part of how these "work."

Circuitmike

Glad you got the scope out. Nice to see the waveform in action. :)

Broxie

After many years of watching Big Clive videos I still laugh every time you "test" if a circuit board has discharged all its caps with your finger.

Jon Knight

I recently built an ultrasonic "dog whistle", but without an oscilloscope to test it, I'm not sure if it actually works or not. :) Interesting technology, I would also be interested in hearing other people's experiences.

Todd Sharp

I'll check that out. I had problems applying audio processing to the whole video, so had to do it in each individual segment.

Big Clive

They're younger than me, so theoretically a tuned siren would work if I kept it just above my hearing frequency threshold.

Big Clive

I'm not surprised to see / hear glitching. Depending on the micro, it can be quite hard to achieve glitchless PWM sweeping. On PICs for example the PWM duty has a shadow register for glitchless reload; but when you want to modify frequency (PR2) *at the same time* it gets a bit fiddly.

Mike Page

And it's only being driven from 5Vpp. On one project (for *reasons*) I ended up generating a 15V rail (from 2 x AAA) and using bridge drive, and the thing still wasn't very loud.

Mike Page

That "pizza" disc is tuned to around 3kHz. It will of course produce sound (24kHz - 65kHz) but at a very very (yes 2 very's) low level. Like using your subwoofer as a treble speaker.

Zeedijk Mike

What's that ticking noise? - It's Fred... He's a metronome! (David Bowie)

Zeedijk Mike

At Uni we got a "mosquito repellent" kit to assemble. It sounded like a noisy switch mode power supply.

Wim

I have to say that there is something to watching you draw the schematic! I didn't notice until now. Or maybe my stupid braiiiin. LOL :D (Shut up brain or I'll stab you with a Q-Tip!)

Michael Thompson

Clive heard the repellent and naturally left the room...

Michael Thompson

I don't think these devices make any difference. A bit like the cat and rodent deterrents you are meant to place in your garden or house.

Jeremy Travis

I do have to make the comment, that your audio levels were up and down almost as much as the frequency of this thing in that vid! Perhaps the mic was too close, as your voice was eather way too quiet in some places or too loud in others depending on where I set the volume! I am curious as to how they both destroyed the LEDs, as they didn't seem stupidly over driven, and were pulsed as well it seems!

William Taylor

I've always been told they are a scam. The only time I have seen one in person it was covered with roach droppings as they were obviously living inside it. It was much larger in size than these were as it was decades ago (mid 90's perhaps ?). That's just a single observation, hardly conclusive evidence but it's what I saw.

Sample-Text

You should see if it works on drunk pests from the MBC, might save your eyebrows next time.

Mike Wynne

I once worked for a retailer that sold these and while the efficacy is disputed (and they really shouldn't be used if you have pets), I will say that they were very rarely returned - so either they did something, or the customers purchasing them were already bought into the concept of them doing something. They've really come down in size , they used to be large enough to cover 2 power outlets.

Michael Buchan