Project - Help/Advice needed

[chuangt2u]

Evening all.

Firstly, many thanks for taking the time to read through this post and hopefully being able to help. I'm looking for some advice and or help with a small project I'm working on as I have zero electrical knowledge.

I'm working on building a mosquito trap. This is not a commercial enterprise, and full plans will be openly released when the project is complete.

I live in Phnom Penh, Cambodia, and after recently recovering from a dose of dengue fever (mosquito borne), I decided to try to "get even" and try to develop a trap that can be built from locally available materials, for as little as possible, and that can be left alone to run with minimal maintenance and use minimal resources

Cambodia is one of the poorest countries in SEA, and this machine has to be within the budget, build capability, and resource availability of the majority of Cambodians.

After some research, I have found an effective bait and designed a trap - the next step is to develop an effective killing mechanism - and this is where I need the advice.

I'm thinking of rigging up a "bug zapper" using a motorcycle battery as a power source. Is this feasible? Would the discharge be large enough? If so, are there any pratfalls or dangers I should be aware of?

I'm also thinking of running a small computer fan (12v DC, 0.15a) from the same battery. Could I just hook up the fan - would it just draw what it needs or would the battery just burn it out? If I can't connect the battery directly to the fan, what do I need to include in the circuit to make it work?

I have a small personal budget for this project that, although small, is considerably more than rural Cambodians would have available; any ideas/solutions need to be cheap and easily made - to give you an idea, my total spend needs to be below $15US, including battery.

If you've got this far in reading this, many thanks for your time and hopefully your help.

Cheers
C

 

[Des 56]

Interesting project
Will have a think about it for a while and make some suggestions
Is it feasable,I would say very feasable
The fan should be of minor concern

You have come to a helpful place,Im sure the members will give you the ideas that can make it realistic

Oh and by the way Good afternoon

 

[boatnik1]

Can only help with the fan bit, The 12v fan will only use the current it needs from 12v Battery, the battery wont burn it out. We have bug zappers here that work with a UV lamp but I'm not sure if the lamp just attracts the bugs or what mechanism kills them, I suspect it might involve inverters { similar to battery driven flourescents) and high voltages. Good luck anyway and welcome to the forum.

 

[chuangt2u]

Hey, that was quick!

Thanks lads, any input most gratefully welcome.

Good news about the fan, keeps things simple. That's how it needs to be.

I have an old Chinese made bug zapper here that I took apart to try to see how it worked. Apart from the blue bulbs, the mains electricity goes directly (via a switch and a tiny fuse) to 2 metal grids placed closely together. The bug, I assume, connects the two when it flies through and forms a bridge between the 2 resulting in a short. It must be very quick as the fuse didn't blow at any time when it was used. I hope to be doing something similar with the 'bike battery.

 

[Graeme Harrold]

You need one of these and copy it. Runs off a few smal batteries in the handle......

Bug Zpaaing Bat

 

[boatnik1]

You need one of these and copy it. Runs off a few smal batteries in the handle......

Bug Zpaaing Bat

I think the problem with these is that the works are encapsulated in resin to make it difficult to copy and to use it a switch is pressed to put life into the grid making it only useable intermittently and not as a standalone unattended zapper and is probably evil on batteries.

I would be looking at the electronics in a 12v caravan/boat flourescent to get the higher voltages for the grids. In these the battery voltage is inverted then transformed up to mains voltage to power the tube. Im not sure what the battery consumption would be as there would only be the electronics using power chargeing a capacitor except when the bug shorts it out

I would suggest a lot of care is taken when playing with these things as you might not easily forget the result if you accidently stick your fingers in it.

 

[chuangt2u]

Ok,

got a 5a/h motorcycle battery for $10 (new) and stripped the guts out of a tennis racquet zapper, just keeping the head and empty handle parts. This gives me a good idea of mesh size to use in the device - nice one GH.

Directly connected the battery and then tickled the racquet with some splayed wires.

There's enough power there to melt the thin copper wires, so the mozzies will stand no chance...

YouTube clip here, but it's clearer on YouTubes own site. [ame="http://www.youtube.com/watch?v=eSkANCqsqu0"]http://www.youtube.com/watch?v=eSkANCqsqu0[/ame]


Next questions, if I may.

If the current in the grids is just sitting there and not moving, waiting for a short:

1. Will the power create any electrical fields?

2. How long will a fully charged new battery last if it's not constantly discharged/charged (ballpark figure)?

3. What size/type of fuse will this need to keep things safe?

This is looking good, gentlemen, looking good.

 

[Des 56]

1 No
2
As its new it may last for a very long time(perhaps a few months) make sure there is little or no tracking caused by moisture etc
Discharging and charging a battery helps it retain its capacity in the long run rather than sitting idle deteriorating
3
It depends on the current carrying capacity of the wires,also being low enough to protect the battery from dis integration during the short circuit
It may be wise to have a current limiting capability as well as fusing

Have you anything in circuit to produce the higher voltage that would be required to kill the insects
I dont think battery voltage will be much use at all ?

Its a low Dc voltage and you will need to step this up for bug busting capability

 

[chuangt2u]

I've nothing else at all in the circuit apart from a basic switch, so the whole of the battery is discharging during each contact. It seems to be quite strong as it's melting copper filaments that I brush over it.

It's night-time here now so the light's bad for working outdoors, but I have a resting trap set outside for the night insects - I'll try it out on them in the morning and if it works, I'll post up another video tomorrow.

How can I easily find/build a current limiter? Could I find one in any regular household/car/motorbike items and use it?



Edit


Well, there's definitely enough power in the battery to zap the insects, but the design of the tennis racquet grids wouldn't allow them to fly through easily, so they weren't trying much. I got one or two that were freely flying around though, so the basic concept is proven.