want to build a VHF sounder device

[Pedro]

Please could someone advise me where I can get a kit or even instructions to
build a device that emits a very high frequency 17.5-18.5 kHz tone.

I am not an experienced electronics expert but could manage a simple
project.

Thanks

 

[Rich Grise]

First, 18KHz sound is not considered "VHF". VHF is a radio term.

Are you after a noisy dog? If so, I have a lot of sympathy. A neighbor had
a pit bull that would not STFU! So, took a cheap piezo tweeter, an eighty
watt amplifier, and a signal generator. As soon as the pooch would start
up I would blast it. It worked every time. I set the frequency to just
above what I could hear. It was about 18KHz, as I recall. The trick is to
only leave it on long enough to stop the barking, otherwise it'll get used
to it.

You should set it up with a microphone, so that when the dog barks, it
gets pinged.

The easiest thing, for you, would be to build the signal generator (a 555
would work nicely) but purchase the amplifier and speaker. A cheap car amp
and a cheap 12V supply (like from a computer) will work well.

I concur here, but OP will probably need to invest in a book or two (or at
least invest some time studying on-line).

Cheers!
Rich

 

[Jasen Betts]

Please could someone advise me where I can get a kit or even instructions to
build a device that emits a very high frequency 17.5-18.5 kHz tone.

18 kHz(+/-3%) is not VHF, not even technically ultrasonic.

I am not an experienced electronics expert but could manage a simple
project.

.-------------------------------------------------------------.
| This is an ascii schematic, if the diagram appears garbled |
| try switching to a fixed-pitch font (courier works well) |
| pasting it into notepad works well on ms-windows. |
| or in google groups "show original" (in "more options") |
`-------------------------------------------------------------'


S E M I - P R E C I S I O N D O G A N N O Y E R


+6V -+------------------+----------+--
| | |
R1 `-[100Ω]-. . . . .|. . . . |
\ | . VCC(8) . |
/ | . . |
\<---------+---DIS(7) RES(4)----'
2K / . NE555 . |
\ +----------TH(6) OUT3(4)--------+--------|
R2 / | . . | | piezo speaker
| +----------TR(2) CV(5)--. | .---|
| | . . | | | |
+---+ . GND(1) . | | |
| . . . .|. . . . | | |
| | | `----|---[10KΩ]---+
C1 === | | | |
| 22nF | === 10nF +---[1KΩ]----+---->
| NP0 | | | TO 3.5mm plug
0V -+----------------+--------+----------+----------------->

the chip should be LM555 or NE555, C1 should be an NP0 ceramic type
R2 should be a multi-turn trimpot.

build this then plug it into your computer's line in jack and view
the wave on a program like audacity adjust R2 to get as close to
18Khz as you can.

Bye.
Jasen