Ultrasonic pest repeller teardown 

I had a roommate maybe 15 years ago, back when these ultrasonic pest repellers were still the subject of infomercials, who brought her very own private collection of cockroaches when she moved in. The infestation lasted longer than her tenancy. I tried a lot of things to get rid of them. I finally broke down and bought three of these pest repellers that claimed to expell all manner of creepy crawlies, even though they were quite expensive at the time. Well, the roaches promptly built colonies inside their cheap plastic cases. I'd say they were somewhat ineffective.

I plugged 6 in one weekend. All three daughters moved out the next day. They worked for me!

In the early 90s, my aunt put an early Japanese-made version of these in my grandparents' cabin. Being, oh, about thirty years younger, I discovered I could hear it... it was loud enough to wake me up in the middle of the night when she turned it on. A subsequent hearing test (some months later) showed I could hear up to 24 kHz. These aged, abused ears probably can't go near that now, but it was still pretty cool.

I've tried these things, they're dirt cheap usually. Some of then are audible to the younger folks, others turn out to be just an LED. None of them ever repelled any "pests" (mosquitto's) for me. This device seems quite nice. Elaborate circuitry with the sweeping frequencies and "breathing" LED. Great video.

Re: effectiveness of ultrasonic repellers. My personal experience is that they did nothing for existing pests -- the mice knew where the food was, and could brave the annoyance to get to it -- but after they were gone they were remarkably effective at preventing *new* pests. They just ran away from the annoyance and never learned it was worth overcoming it. So, not completely effective in and of themselves, but a good deterrent for places that are likely to be interesting for pests but not yet infested.

Glad you ‘scoped it - really gives insight into what they’re trying to do!

Enjoyed the "on the fly" schematic! Cool stuff!

As a pest control technician, I can confidently say these things do not work. Seal up all gaps in your property bigger than 3mm to keep mice out as you cannot target field mice with rodenticide, because they are protected (everything eats them)

Call me a sadomachochist but I'm kinda waiting for the day "Is the capacitor discharged" returns a definitive "No".

Appreciate letting us watch you draw out the schematic w/breakdown explanation. Really adds to the experience.

As someone who struggles with reverse engineering stuff I rather like how you do it on the fly explaining. If people don't like it they can drag that slider forward.

This is a rare instance, Clive has pulled out the silly scope. Bookmarking this for my collection.

As soon as I seen the rodent repeller, I was hoping you'd get the scope out. I actually punched the air when you said you where getting the key sight out. I always wondered what wave form these outputted.

"Let's zoom back out and explode the circuitry" is what I heard at time 4:35

I was working at a food truck that had these plugged in EVERYWHERE. Finally convinced the owner to ditch them as they're basically giant "HEY THE OWNER THINKS OUR TRUCK IS INFESTED WITH BUGS" signs

My local shop set up a speaker outside their door which played classical music after 4pm every day. It worked! No more teenagers hanging around outside his shop and nicking stuff!

The coder was flexing at this point with that PWM LED effect. Frequency sweep was quite fancy as it was.

Apple called their modulating LED a THROBBING LED, a bit of tongue in cheek (or elsewhere) humor. Despite his reputation, Steve Jobs actually had a good sense of humor. The repeller LED uses PWM modulation to achieve the throbbing effect, which is why they used a uP to do 2 tasks at once. Nice to see that you finally employed an oscilloscope, a Keysight at that. Nice!

I'm a plumber, they don't work. Waste of energy, and often head ache inducing. Mice will choose deaf/headache over freezing/starving. This will just breed mice with lower frequency limits to their hearing if it does anything of consequence at all.

I bought one of these pest wall warts 5yrs ago and took it apart. It was much larger thab these and its circuit was all discrete thru hole components, based around a 556 timer driving one of those brass colored piezo discs. It reminded me a bit of the coin-tone phone phreaking circuit i built back in high school - for educational purposes , of course :)

I was expecting a capacitor and an LED, but I liked that it is real for once, and really liked seeing the graph about the waveform. You can buy one for a breathing nightlight, the ultrasonic part could even be disconnected when all the rodents left the city :)

Thanks big guy. You helped me convince my wife this doesn't work and saved us money.

Many thanks for doing the reverse-engineering in-camera Clive! I find it much easier to follow and feel like I am learning something. It is simple to scrub forward if anyone just wants to get to the next bit. Even more so the soldering--a brilliant tip for removing small SMT devices and _much_ quicker that getting the hot-air setup out! These things appeared in the little-known post-apocalyptic RPG 'RIFTS'. You could buy tiny ones to put inside your power armour and giant robot suits to keep the tics and like at bay. I always think of that when I hear of them.

To prove that the younger you are, the wider your hearing perception, I plugged one of these in (to scare away Garbage nighttime thieves) and both my boys ran up from downstairs saying "What the hell is that noise"!!...I cannot hear a damn thing.

The "breathing" effect is, as you said, controlling the PWM, but its a very simple natural log scale that doubles the brightness at each step.

I have an old (wrecked) recording studio about 80' x 15' I use as a store. I have 3 traps which are baited twice a week. I was catching 6 mice a month until I put 2 sonic repellers in (June 21) - I haven't caught one since! (I take on board what others have said about the mice 'acclimatizing' though). Love the video!

I just love it when he says "one moment please" and we can see the reverse eng circuit board and all

I've always considered these devices to be snake oil. Interesting little board though.

I've never bothered getting one of these. The instructions say that the area around them has to be fairly open and clear, and that doesn't describe my flat.

My uncle bought a 6 pack of the cheaper ones and I opened it up and it was just a 555 running at 15v (no zener) at about 23k to 25khz single tone. Seems to have kept rodents away from the side of our house. I saw way less rat poop after plugging one in. Regarding the soldering on the piezo disc, I found that using solder with 2% silver alloy eliminates the issue of dissolving the metalization on the ceramic part.

I was wondering about scope connection. Good video, thanks Clive.

I've been in enough homes doing pest control to say these are not very effective. Roaches love to nest behind they because of how warm they are. Mice and spiders just ignore them.

"is it discharged yet?" rather than using the finger I use my tongue because it is more sensitive. 😆As a kid I used my tongue to check if a 9V battery still had some juice left in it that is good for something. I am too glad that you revealed the sonic output with the scope. Any of the modern low cost MCUs has at least one or more programmable timers with divider which is the most efficient way to generate the desired square pulse train output. The sweeping must be done with an algorithm loop in that each time through it it steps to a different timer divider setting - hence the next step of the sweep. It would had been nice had you monitor the LED and the sonic signal simultaneously with two scope channels if they are related. This is a nice looking and good quality product. The ones I have over the pond here in the big continent have the casing glued together so you have to break it to snoop what is inside. Mine are a trusted pest control brand. Thankfully with just a fixed LED. I have multiple of then in the motorhome and the breathing LEDs would be annoying at night.

I remember years ago a friend had an ultrasound generator, if we aimed it at moths they would fly erratically and then land. I presume the sound was close to that made by bats and the moths were trying to avoid them.

Bit late to the party , just found your channel. It is excellent.

Excellent break down and of course the workings of the electronics. Thoroughly enjoying your videos. Very informative, fun and interesting insight into the many gadgets we take for granted. Some that are very cheap quality and others that are better.

Well, what do you know, I hop onto the RU-vids after getting home, and I am greeted with a wonderful new upload!

I belive the models with only the LED are equally effective

When I was younger I could hear some ultra sonic frequencies (not all). I wasn't something I heard by my ears, but heard in my head. Anyway, I was on a breakfix job and the old boy had one by the front door and was working, so I had to stand way back. When he opened the door he asked why I was half way down the garen and explained the noise. It apprently was to scare cats. After doing to job, he asked me about the ones at the back which he wasn't sure about. One was working, the other wasn't. He changed the batteries and he had it on pulse. He tried to test me by not turning it on and saying it was, but I confirmed the on / off.

Shawn Woods, RU-vidr with a pest control channel, has tested these units and found they don't work. I certainly wouldn't buy one.

I've opened some of these, and it seems that most of them use a capacitative dropper, a zener diode but a 555 in astable mode to generate the ultrasonic oscillations for the piezo. I use one of these repeller just for led as a nightlight

brilliant as always! I would've liked to see the frequency spectrum of the signal at 13:09, we could see the center frequency increasing, and also the loud harmonics of the square wave, which would explain why the younger population can hear it since a 23kHz square wave will have some "leakage" into the audible spectrum.

"Has it discharged yet?" - insert fat finger - "yes it has". Legend :-)

Back in the 1970's and 1980's I used to make these based on the old 555 timer chips. One as the HF driver and the other as a LF sweep for the 555. I found they work for only a short time until the mice and rats learn to dig into the insulation of the house deeper and down into the walls. So Yes short term they worked long term the rodents did not care. But in the 1990's I was hired to build a very high powered ultrasonic unit by a guy that wanted to see if it would work to chase Bears away and if it worked then he would develop a product to do that. I guess he snuck the unit I made into a local Zoo and tried it on the bears they had to see what happened. I never heard from him again.

"The world is full of con-TRO-versy." I see what you did there.

I find it hilarious that you could give Clyde a Space Shuttle and ask him to "take it to bits" in a video and the part he'd be intimidated by is the amount of white to balance out without blowing out the picture. LOL

I was confused for a moment until I realized the title didn't say "ultrasonic pest propeller"

Great work Clive. Enough with the fillers, let's get back to the ozone. :)

that circuit is one of the best solutions I have seen yet.

I used the ultrasonic dog repeller ,and it worked for wild dogs ,but you can hear the high picth sketch sound but very faint when you got your ear near it

Another good video by the way. Sorry for this long post but it was hard to explain in a shorter version. I am a Ham Radio Operator and these things can cause a real problem on the receive side of the radio. A friend of mine had all sort of problems with noise on his radio that he had fought for months. He ask me to stop be and see if I could find it. Keep in mind he had called the power company, telephone company, and the FCC but nothing ever got done. So I went there and heard this awful clicking and buzzing on the radio. OK first things first, I turned every switch off in the house and unplugged everything except the radio, problem still there. So now I go out and get a car battery and used that on the radio with the house all off, still got the noise. He had a building out in the back that had it's own power supply. He used it for exoitc birds. I was in there looking at the birds when I look down at the floor and a AC plug that had a device plugged in it. I asked him, What is that for? And was told that it was to keep the bugs and cats out. Then it hit me, I bet that is what we are hearing. We got a handy talky each and I told him to turn the power back on and turn on the radio. I said you got the noise still? Yes he replied. I then unplugged the buggie thing and asked again. He said no it has all gone. He was one happy old man. So Ham Radio Operators this should be the first thing you should check if you or even you neighbors have one.

I always hear a very high pitched squealing sound with these. I'm always told no you can't hear that, but I know what I hear. It's like a Dramel tool running by itself but turned down or nearly muted.

It was nice to see the oscilloscope being used. Personally I think they are a scam.

My local co-op at Christmas used to have a giant Santa that played jingle bells very load and distorted whenever anyone nudged it They used to groan every time it played. I set it off many many times and I can vouch they never got used to it ...

One day at work I was being driven mad by these really loud, really high pitched tones for ages. A couple of guys about 30 feet away noticed me looking around and asked “can you hear that?” They’d been playing with a hearing test app on their phone and couldn’t hear anything in that high range themselves so had no idea how annoying they’d been.

I'm still waiting for the day BigClive goes: "Has the capacitor discharged? Let's find ouOUTCH! &*@!@!*&@#"

Once during my college days, I walked into a lab and asked, "What's making that sound?", only to have everyone start laughing. Somebody was demonstrating a frequency generator to some visiting students, and he was doing the, "This is the highest frequency my father can hear.", turned up the frequency, "This is the highest frequency I can hear.", turned up the frequency, "And this frequency, only dogs can hear."... then I walked in.

Ultrasonic repellers won't rid your whole home of mice, but what I have found is that strategically placed, they can encourage the rodents to move to other locations in the house where the noise is not so loud...

Those orange and blue SPK +/- dots make me think about railroad signal aspects for some reason.

Just what I needed something to watch in the wee small hours of the morning when I couldn't sleep, thanks Clive, good and interesting video.

"PCB Vice?" Laughs in Big Clive

I don't think that my cat will appreciate it when I use one of these.

Thanks Clive, enjoyed that. I have catz, no rodent issues here. ;) I did modify some similar units for a guy who wanted PIR function.

At the robot repair shop. "Grandpa says he has a ringing in his ears." "Hmm.. how long has this been going on?" "Well, it's ever since he bought that pest-repeller on RoBay." 8oO oO~ oO~ oO~

For the recent viewers, always remember to check out other videos from our friendly Scot, suggested starting point is Fanny Flambeaux, remember to have a hanky ready! Cheers from Oz.

Good Monday morning to you sir from Wellington Somerset

I bought something similar about a year ago. It did drive the rodents away, and the little buggers haven't come back yet. Seems to help with mosquitoes as well. Other electronic mossie repellers haven't worked in the past, despite a certificate inside signed by a German uni professor.

I had one of those, here in Australia (the land of bugs), they do nothing, other than use power. I noticed after some months that it had degraded, and the frequencies it was putting out were becoming more audible. But it was clear that the things it claimed to keep away weren't bothered by it in the least.

I'll bet it is a Tiny85 MCU on that board or something in that range. The LED is probably just connected to the complementary PWM cause you just got to have a fancy LED in your product.

My roommate bought a bunch of these and plugged them in. I subsequently unplugged them because I couldn't stand the whining pitch they put out, and they did bugger all for pests.

I had one, and that one was based on 555 giving out steady 32kHz. Objective was to repeal mosquitoes s but nobody informed mosquitoes that they should be afraid of it, so no effect.

I have one but I am not convinced that it works and the poison bait traps would suggest not either. 😳

"Has it discharged yet? ... yes it has" 😂

3:47 Love the single-digit (index finger) discharge tester.

👍 Danke fürs Hochladen! 👍 Thanks for uploading! 👍 Very good and beautiful, thank you! 👍 Sehr gut und schön, danke!

Yet another superb video. This one was "ULTRA - Amazing" .

Well this video only repelled 12 (At the time of writing) So, doing better than the unit featured. Keep up the good work.

I wish I could have visited the Meetup but travelling across the world is out of the question for my budget Glad we'll get to see the cool stuff you received though

Oscilloscope on the LED contacts would show if the frequency is indeed the same...

It kept me away from a friend's house for awhile. Cheers

I ran some trials with ultra-sonic repellent gadgets while working in the Entomology Dept at University. They didnt appear to do anything to deter ants, scorpions, crickets, or termites. They MAY have had an effect on cockroaches, but the trial was only that; not a full study.

Do these things really work? I built one around 50 years ago with a horn tweeter. The only thing it disturbed was our pet dog! Thanks Clive for your really enjoyable tutorials. Roger.

Scope that PWM of the LED! Maybe they are simply varying the duty cycle? It was for sure much faster than the audio sweep.

Maybe it's not picked up by the microphone or the sound isn't produced by my TV speakers but IRL I can hear these things

Can't say these work (if at all). Used a few in one of our outhouses, and there was no noticeable difference in the presence of our "smaller wildlife".

Waiting for the day where Clive pokes his fingers across the Cap in order to check if it holds a charge and get one hell of a zing of these things just like over on ElectroBoom :D Stay safe and keep up the real nice work Clive,

Idk if it's because the ones we had were cheap but then we had them at work many of us could hear them. They also gave most ppl headaches.we couldn't have them in any prep areas only in the dry storage. Places where people aren't just hanging out

One time I found "pest repeller" that had probably everything inside, it was like there was some chinese company that had bunch of stuff and had to use it, they where called ""Home Sentinel by Aspectek"", that huge one 6in1. It had weird buzzer, pseudo-UV LEDs in front, negative ion generator stuck inside(behind board with no holes...), green night light with photo-resistor at the bottom, some weird coil and hi voltage generator that was supposed to be main "electro-magnetic" repeller. And some weird chip that I had no idea what it was, but when I tried to search for number on top it showed me... circuit board from ABS drivers that had that chip on it...

I worked for a short stent at a nasty sewer treatment plant. They had similar ones everywhere. I mean Every outlet in every room had them plugged in. Bug poisons chemicals were not allowed to be used here. They DID NOT WORK. Cockroaches, flies and rats were heavy at this place. I was sooo glad to be away from that place. But they tried… there were so many bugs you could hear them running across the concrete floors at dark. Eww.. it was a very bad place. There was so many bugs they would set off the motion sensor lights

Oh the preview pic shows "..pest repeller" that word must be cropped on my phone. *opens video* Oh ok, today I learned a new meaning of the word pest.

My parents used to have an "ultrasonic" cat repeller to keep the neighbors cats from spraying around their front porch. It didn't really help and the sound was completely audible to me even though they never heard it. High pitch, fairly loud, continuous tone. They finally took mercy on me and got rid of it.

The square wave intentionally attracts squares with money, ready to buy a gadget. 💸

"I put these in my house, and after I swept all the food off the floor, all the bugs disappeared!"

1:22 Now you know how wedding photographers feel.

What's the piezo's resonant frequency? You could tell using a microphone or by measuring the current into the pizeo (handy 100 ohm resistor to do that with). I think this micro would have two PWM controllers and they are assigned to those two pins. The software just sets the duty and frequency settings every 100ms or something. The micro is what contains the timers and such to achieve the PWM output.

ty for all the content Clive, cheers

I keep one of those pest repellers in my toolbox. It's a great way to test if a socket face is connected while working on electrics, just in case some other bugger has flipped the breakers back on while everyone else is trying to do some work. Admittedly a proper device would be better, but if that light comes on when I plug it in then someone is getting an earful.

I reversed the polarity on mine and it started to attract the rodents. Read the manual carefully before using!

R10 functions to deplete large 220uF. As built, the RC time-constant is 0.2s. Increasing the value to 10k (as you suggested) would result in a very slow "off" time

I have a mate that works at a local sugar refinery and I just had to ask how they battle ants.They use frequency generators ,and yup they work ,no ants at all.so I guess rodents also have a frequency that pisses em off too.I can however assume some of these are not tested on actual rodents and are useless also what range and volume they put out could be a factor also.Maybe get a live rat and test.would be an interesting experiment to watch.Keep up the great work.