mosquito repeller

[arcom]

Hello!

I found this schematic in some dark place on my HDD and I don't know the values of the capacitors and resistors used. As for the transistors, I think that any general purpose NPN transistors can be used. Am I right?

Please help.


Schematic:
www.aquasport.hr/images/1015D.gif
(I tried posting a picture, but that didn't work...)

 

[john1]

Hi arcom,

I have seen mosquito attractors made like that.
Its a square wave generator.
The frequency to attract mosquitos is about 3
kilocycles i think but im a bit vague about that.

I think they are somewhat attracted to each other,
and the sound is like more mosquitos.

I dont see how this could be a repellant,
but it might be used,
to draw them outside from the house.

Or to draw any inside the house into a trap.

See what others say, im assuming that 'W'
is a tweeter.

Regards, John

 

[kinjalgp]

I have used this type of repellers which are useless. In the beginning it was useful but later on I think the mosquitoes got used to it.

 

[arcom]

Thanks for your replies.
I think the frequency (to repell them) is somewhere around 5 kHz but I'm not sure. Do you know the values of components used in the circuit? I only need the device to work 2 months a year...

 

[john1]

Hi arcom,

As you have come back on this,
maybe you actually want to make it.

I dont know what 'M' is, maybe an electrostatic LS ?
The chances of you having one knocking about are slim.

I would suggest an old earpiece, one of those magnetic
diaphragm ones, even one of those tiny little new ones
might do at those frequencies.

I dont like the way 'M' is strung across the two
collectors, i would put a cap in series with it,
that would not affect its function at all.
(0.1 mfd ?)

First off, a small box.
I tend to build everything on the lid,
it makes things easier to work on.
Mount the switch, battery, and earpiece.

That frequency is audible although at the top end of
most peoples hearing, so i wouldnt bother with a lamp
which would probably drain the battery quicker than
the oscillator anyway.

It doesn't need to be loud, so you're aiming at low
current from the battery, i would suggest around 7k
in the collectors, for small npn TRs like 108 or
similar. Base resistors, hard to say, i would guess
at between 100k to 1M, you'll have to fiddle about.

The capacitors, again, they depend on the other bits
i would guess at about 0.005 mfd to start, increase
a bit to reduce frequency, decrease a bit to raise.

I think the frequency is actually quite critical to
do the job.

Again, i had thought these things were to attract
mosquitoes, not to repel them, but kinjalgp says he
has used them.
He also says they are useless.
Maybe the frequency has to be 'tuned' to the local
mosquitoes.
Maybe its job is to attract them,
and you have to position it carefully,
so it would divert them from the window or door.

Maybe it is for indoor use, to attract them to a
trap or to an 'insecticutor'

I am not convinced it will repel them.

Best of luck with it,
John

 

[bogdanfirst]

from what i heard, the repeland works around 15-20Khz, it is the sound made by the male to repell the female, wich "byte" you.
it works for some time, but the problem is that the "small flying, nightmare creator insects" get used to it.
so a constant sound, or a sound that repeats doesnt do.
somebody suggested me to use a noise creator and from the noise to to get a variable voltage and make a voltage controlled osc and so the sound varies in a random way.
i would go for a ultraviolet lamp with high voltage grid around it, id gets read of your "bugs" form the brain permanent, but they have learned to get away from this too.
are we hopeless? hope not.!

 

[arcom]

M is a piezo buzzer (and I have about a dozen of them)... the only problem is that I can't find the exact parts list. Also, as you said it jonh1, the frequency of the oscillator is critical.

I'll try with these values. Hope it will work.
(WANTED: Mosquito for a lab rat. Preferably with good hearing )

The only reason why I'm building this circuit is because those darn blood-suckers got used to all types od chemical repellants (perhaps they mutated into super-mosquitos). Hopefully it will give me some peaceful nights during the summer. If not...I'm switchin' on to the extreme measures...

 

[bogdanfirst]

the frequency.
i have a book on electronics, a littel bit old, but it describes the way the "flyers" react ro sound.
it says that a frequency of 16-100KHz is very annoing to the females, wich cause the problem and suck your blood.
but, there is a "but" they have made experiments and concluded that they are sensible to 10-15KHz, and tend to go awqy from the source.
they have 2 schematics, on for 10KHz and one adjustable from 1.9 to 15KHz.
i could give the schematics but they are simple oscilators and the components are old, not to be found. germanium transistors

 

[arcom]

Can you please send me the schematics anyway. I'll try to make something out of it...
If nothing else works, I'll build an oscillator with the 555 timer IC.