Mosquito alarm equivalents?

Not for a tenner but a few tenners yes. Then make is fully waterproof, add a warranty, acquire countless approvals, market it etc and then only sell a few thousand tops(?)

Maybe you are confusing cost and price in a market place where organisations are footing the bill, there is no pressure to keep prices low as there would be selling into a consumer market.

Bob

You could use a hosepipe on them cheaper, [1] assuming we consider /also/ potentially assaulting innocent people acceptable here (as we do with such gadgets)?

I say this as the parent of a child who used to 'suffer' cat / pest repellant's as she innocently walked down the road.

Cheers, T i m

Of course you could. In fact you could do it for a few pence ... It's a 555 timer IC (pence) , a couple of resistors (pence), a couple of caps (pence), a pot to adjust the frequency so you can adjust it to match the frequency of the beating wings of the female (pence), a piezo buzzer element (pence), and maybe a small driver transistor if you want it to have a good range (pence). Apart from this, all you are going to need is a box, battery holder and a switch. Change out of a fiver. I seem to remember Practically Witless magazine doing one as a project probably 40 years ago.

If you bung "555 based mosquito repellant" into Google, you will get cartloads of hits. There are also plenty of schematics based around an astable made up from two transistors and a handful of components, but the

Arfa

On Tue, 03 Aug 2010 15:08:41 +0100 someone who may be T i m wrote this:-

I find being polite to teenagers, as I am to any other group of people, is far more effective in the long term than some undiscriminating gadget which understandably makes teenagers resent old people like me.

They are not alarms, they are indiscriminate weapons.

MEPs have the right idea, "A committee of MEPs voted unanimously for a Europe-wide ban on the marketing, sale and use of the Mosquito acoustic youth dispersal devices in all public places."

--

Actually the kids are way ahead of us and have been using the high frequencies on their mobile ring tones for some time. If you want to know how old you are, this site seems disappointingly accurate. Try it:

If you want to feel your age:

Sounds like a good way to get a noise abatement order imposed on you. Just because you can't hear it doesn't stop it being a nuisance if someone reports you. Its not just teenagers that can hear it but babies and young children as well as dogs, cats, maybe bats and other protected species.

sound, but it's just not as clear as the slower ones), but not the

My hearing's somewhat shot though (too many rock concerts and pub gigs in my youth, too many engines and angle grinders as I've got older :-) so it's nice to know that I can at least still hear the expected frequencies (what I do find extremely difficult are things such as hearing someone talking when there's a lot of background noise)

cheers

Jules

Me too - concertwise: but I always thought I had one very good ear because I can't stand watches ticking in quiet rooms. Sad to say the problem is really one bad ear, not one good one!

Some of the frequencies quoted are wrong, the sounds seem to be 10 kHz less than they should be. Also, your computer's sound system might be less sensitive at higher frequencies.

I can hear the '18.8 kHz' sound via the tichy speakers in my flat monitor, and I'm 40.

Or you could get a Richard Clayderman LP from local charity shop for

Owain

In message , Anita Palley writes

I was talking to a malaria expert (tropical diseases doctor at Edinburgh Uni) and he confirmed that catnip is an effective mosquito repellant. I read it in NS a couple of years ago

Hmm:

Not what the OP was after, but having nuisance youths ripped to pieces by frenzied moggies has a certain appeal...

In message , alexander.keys1 writes

I can hear them all

I'm 92 you know ...

Surely you don't want to buy 5 of them

In message , Spamlet writes

Yeah - I jumped to the middle bit which, in conjunction with the subject gave me a senior moment. Everyone else is having one, why can't I ?

In article , geoff scribeth thus

Thats a symptom of some hearing loss. Try this test on the RNID website. A sequence of numbers are read out and you enter them on your keyboard.

If your rather good at this they increase the noise along with the numbers thus making it more difficult.

Have a go...

Might have to copy and paste..

In a hospital hearing test It might come as a surprise for some to find that they can be 30 odd dB or more even, down from 400 Hz to around 8 kHz and then might worry about their amp being within a .1 of a dB from DC to Daylight;!...

Won't work. Last time I looked at this, the squeaker involved (decent efficiency at the frequency involved, reasonable power capacity) was around a tenner. You don't just need it to be "a bit annoying", it has to be heard over background noises, iPods etc.

Also using 555s as an audio oscillator is unlikely to be stable enough, given the environmental variation (mostly heat) for anything in an external box on a sunny or icy wall. Really though, just using a

If you're trying to install one of these things, a bat detector is useful too. Or else a calibrated teenager.