7/23/2019 Ultrasonic Dog Whistle

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Ultrasonic Dog Whistle

Circuit NotesIt's well known that many animals are particularly sensitive to high-

frequency sounds that humans can't hear !any commercial pest repellers"ased on this principle are availa"le# most of them operating in the rangeof $% to &% k(

!y aim was# however# to design a slightly different and somewhat morepowerful audio frequency)ultrasonic sound generator that could "e used totrain dogs *ust imagine the possi"ilities - you could make your pet thinktwice "efore "arking again in the middle of the night or even su"due hostiledogs +and I guess "urglars would love that,

.rom what I've read# dogs and other mammals of similar si(e "ehave muchdifferently than insects /hey tend to respond "est to frequencies "etween0& and 1& k( and the older ones are less suscepti"le to higher tones /hismeans that an ordinary pest repeller won't work simply "ecause dogs can'thear it /herefore# I decided to construct a new circuit +"ased on thevenera"le && of course with a varia"le pitch and a relatively loud 21 d3miniature pie(o "eeper

/he circuit is very simple and can "e easily assem"led in half an hour !ost

of the components are not really critical# "ut you should keep in mind thatother values will pro"a"ly change the operating frequency 4otentiometerdetermines the pitch5 higher resistance means lower frequency 6incedifferent dogs react to different frequencies# you'll pro"a"ly have toe7periment a "it to get the most out of this tiny circuit /he circuit is shown"elow5

7/23/2019 Ultrasonic Dog Whistle

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Despite the simplicity of the circuit# there is one little thing /he 0%n. +%0capacitor is critical as it# too# determines the frequency !ost ceramic capsare highly unsta"le and 1%8 tolerance is not unusual at all ighercapacitance means lower frequency and vice-versa .or proper alignmentand ad9ustment# an oscilloscope would "e necessary 6ince I don't haveone# I used Winscope :lthough it's limited to only 11 k(# that's 9ustenough to see how this circuit works

/here is no need to etch a 4C3 for this pro9ect# perf "oard will do /est the

circuit to see how it responds at different frequencies : ;k< potentiometerin con9unction with a 0%n. +or slightly "igger capacitor gives some 00 to11k(# which should do 9ust fine Install the circuit in a small plastic "o7and if you want to# you can add a =>D pilot light 4ower consumption isvery small and a ?@ "attery should last a long time

4ossi"le further e7perimentation5 I'm working on an amplified version of

the whistle to get a louder "eep :ll attempts so far haven't "een successful

as high frequency performance tends to drop dramatically with the &&&

4erhaps I could use a frequency dou"ler circuit - I 9ust don't know and I'verun out of ideas Ane other slightly more advanced pro9ect could "e a

simple Banti-"arkB device with a sound-triggered +clap switch that sets off

the ultrasonic "u((er as soon as your dog starts to "ark

: suita"le pie(o transducer for this pro9ect is availa"le from!aplin

>lectronicspart code W.%?

http://www.maplin.co.uk/http://www.maplin.co.uk/http://www.maplin.co.uk/http://www.maplin.co.uk/