Easy High Voltage Fly Swatter Mod

Introduction: Easy High Voltage Fly Swatter Mod

About: I'm currently a graduate student in chemistry. I like diy solutions, mainly in the field of plants and electronics (especially LEDs).

Caution - High voltage. Keep away from children and pets. I am not responsible for any form of harm done to yourself or others.

So, having said that, I always wanted to adapt a fly swatter to something more serious. Standard electric fly swatters handle what I think to be about 600 to 1000V, this modification would be in the region of 20.000V. Next to that it doesn't require hardcore technical stuff. I wanted to make a cockroft walton generator (which I think is in this module), but that was more expensive and a lot more work. So here is an easy mod by using a cheap ebay component.

Step 1: Parts

  • The main part I used was a high voltage generator from ebay (such as thisone). With the following stated properties:

    input voltage: DC 3 V to 6 V Input current: 2 A - 5 A High pressure type: the type of pulse current Output voltage: 400000 v(Please pay attention to safety) High pressure discharge distance between: 10 mm - 20 mm

    Although they state 400.000 V, this is probably not true. The discharge distance is indeed about 20mm, so that would correspond to roughly 20.000 V, or lets say 10 to 30 kV. Still quite high though. Also they state not to operate it constantly for a long time since it might overheat.
  • So as an input you could use the standard 2x aa in series (note, must be fresh batteries) or a single 14550 Li-Ion battery (ranges between 3 to 4.2 V, can handle a few amps) and a battery spacer such as some tin foil wrapped with tape. Input stated is 3 to 6 V so I didn't try to put two lithium cells in series in it since it might fry the components. But hey you can try it if you want to.
  • Heat shrink tubing or something similar.
  • Solder for a neat job, or twist wires together for quick and dirty.
  • Tools such as soldering iron, pliers.
  • Fly swatter

Step 2: Strip Insides

First of all take out the batteries. Although I didn't do this for some reason, it would have been very smart to do that beforehand.

Next cut all the wires to the old circuitry. Note that you will need a switch, so if possible leave that in place (mine had that option). Next make sure your high voltage generator fits. I had to remove some plastic with wire cutters which was quite easy. Unfortunately no pictures of that. Next put it in.

Step 3: Solder Connections and Insulate

Solder the wires to eachother in a straight line. Make sure to put the heatshrink tubing around the wire before soldering. I used a double layer to be sure it insulated properly, high voltage needs good insulation.

Which wires should go where can be found in the discription from where you buy your generator. With mine the red was +, the green was - and the two translucent red wires were the high voltage wires (polarity doesn't matter). So I soldered the red wire to the positive terminal of the battery, the green wire to one of the terminals of the switch and an extra wire (taken from the original circuitry) from the negative battery terminal to the other switch terminal. These do not necessarily require insulation if they can't move, if they can insulate them.

On the high voltage side the translucent wires should be soldered to the screen. In my case there are 3 screens of which the middle screen has the opposite polarity of the outer two. Therefore the 2 yellow wires (outer screens) need to be soldered to one of the high voltage wires and the red (inner screen) to the other high voltage wire.

Step 4: Put It All Back Together

Put the wires in a place where they might fit and screw it all back together. Insert batteries, apply warning sticker and have fun! Make sure not to zap persons. I don't think the amps are high enough to kill someone but hey better not try.The weird smell you get when you use it for some time is actually ozone being formed by passing the high voltage arc through the air.

Questions? Feel free to comment or send me a message in either Dutch or English.

If you liked this instructable please vote for me!



  • Metalworking Contest

    Metalworking Contest
  • Tiny Home Contest

    Tiny Home Contest
  • Water Contest

    Water Contest

28 Discussions

If the generated voltage is high enough to arc across the grid without a fly in contact with either plate, doesn't that immediately make the voltage across the plates zero and make it ineffective against flies? Is this just for a light show, or does it somehow still prove effective against flies? It seems like it would be better to bring the voltage up to the point where it's ready to arc, but doesn't. It's too bad you cannot adjust the output voltage to optimize...and add a diode and a big storage capacitor to hold a big charge at that voltage. If you're interested, I have modified the $4 Harbor Freight fly swatters to increase the output voltage up to 4X (around 5-6Kv) with good results; and even better results if you spring for a bigger output cap.


1 year ago

Hi, I want to make a high powered zapper that doesn't arc when nothing is in the racket. If I use this high voltage generator instead will it give me the results I want? Though in the description it says:

not exceed the maximum arc distance electricity, energy can not be
released due to high pressure , can easily damage the module."

Does that mean it NEEDS to arc in order to release the energy otherwise it will damage it? If so how can I make it so it doesn't have to arc? The original zapper I have doesn't need to either. Thanks

1 reply

Hi! They do seem to contradict themselves a bit, but yeah I think it does need to arc. I don't know the inner workings of these modules so I'm afraid I can't help you with that. You might try to increase the power of your original zapper a bit with an extra high voltage capacitor across the output, then holding the button longer before hitting the fly might result in more destructive power. Also sometimes there is a high value resistor across the high voltage output to make sure the power is slowly released after you let go of the button. You might remove that or change it for an even higher value resistor, but this might result in keeping power on your swatter for a longer time after releasing the power button.


2 years ago

wait just making sure... Normal fly swatters produce about 1000V but this mod makes it closer to 20,000V?

1 reply

Something in that order I think, yes. Although I just came to realise that the 20 kV estimate comes from the 2cm distance sparking, but the spark gap in the fly swatter is actually a lot shorter. I don't know the inner workings of the module I put in but I think the voltage might decrease and the amount of sparks per second increase when the spark gap is smaller. Taking that into account it might be more like say 5000V, either way it is a lot more than a regular one, that is for sure. Regular swatters have trouble with killing a fly, this one on the other hand... ;)


2 years ago

wait just making sure... Normal fly swatters produce about 1000V but this mod makes it closer to 20,000V?

thankyou the freak

thankyou very mutch freak,i want use high voltage generator with aa battery it is dangerous for human.
when i am going to finish the project i am going to post the photo

1 reply

I don't know if it is dangerous for humans, so just be careful.

the output wires of high voltage generator does not have + or - are the same?? tanks

1 reply

Just connect the 2 wires, doesn't matter how.

tankyou very mutch the list part are:
one 14500 battery
high voltage generator
one switch
there is everything

2 replies

And the flyswatter. Mine already had a switch, so that wasn't needed. Also 2x normal 1.5V AA battery works fine. The 14500 Li-ion battery does need a Li-ion battery charger, so the easy option is to use normal AA batteries. Another option is to use 2x NiMH rechargable batteries. Easiest part list is:

Fly swatter
Two normal AA batteries (or whatever fits in your flyswatter, maybe AAA)
High voltage generator

Oh and something to insulate like heat shrink or electrical tape is important.

i live in italy i can use it http://m.banggood.com/it/DC-3_6V-6V-To-400KV-Boost-Step-Up-Power-Module-High-Voltage-Generator-p-915426.html

1 reply

Looks like the same one I used, so yes I think you can use this.

Hey Man, I really liked your project is AWESOME! But I wonder could only use a module of these for a stun gun to humans (that do not kill, of course) but that works well giving some rsrsrsr scares ...

1 reply

Hi! Thanks you! Yes that same thought came to my mind, I do think it will give you a proper zap, probably enough to function as a stun gun. Some stun guns have voltages in the million range, but considering a normal fly swatter at around a 1000 volts gives you a spastic reflex muscle reaction, this should do fine. My only concern would be safety, I don't know if it is safe. I checked the input voltage and amperage, with a near fresh lithium ion battery I get between 0.6 and 0.8 Amps and 3.5 to 3.6 Volts. The thing is that it is pulsed current so these measurements might be off. Anyway giving this, if I round this the input is about 4W. If the output is 20kV that results in 20.000/4=0.0002A or 0.2 mA which I think is non lethal.

I of course advise against it since I am no expert, but in my mind it might be safe. Nontheless I wouldn't try it on myself. Disclaimer I am not responsable for anything you do ;)

Pity, mine is still working, but then again I hardly use it. Made it just for fun, not because I need it.