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I am looking at designing a small bug zapper circuit of the type described in this post.

Here is an approximate schematic of what I am trying to build:

enter image description here

I have done some research into how this circuit works and also taken apart a mosquito zapper racket and tested the circuit firsthand. From this I've gain a basic understanding of how the circuit works via self oscillation and flyback.

What I'm confused about is how to correctly source the transformer component. I know I need one with 6 leads, but other than that I'm kind of in the dark. The transformer from the unit I took apart had no distinguishing markings so it wasn't much help.

Can anyone tell me what specifications I need in a transformer for this circuit to work?

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    \$\begingroup\$ Cheapest source would be to buy a dollar store mosquito zapper. \$\endgroup\$ Jul 15, 2020 at 3:12
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    \$\begingroup\$ @SpehroPefhany probably true, but I'd like to source my own part if possible. I'm trying to hack this circuit for an art project, have a lot of bug zappers firing rhythmically \$\endgroup\$ Jul 15, 2020 at 3:19
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    \$\begingroup\$ They're custom made for the product, if you specify the core size, ferrite material and all the winding and taping details, you can get a transformer maker to build exactly what your design requires. \$\endgroup\$ Jul 15, 2020 at 3:21
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    \$\begingroup\$ @SpehroPefhany Okay, but I'd assume there are some generic options that would work as well. My question here is related to what specifications a transformer needs to work in this bug zapper circuit. \$\endgroup\$ Jul 15, 2020 at 3:55
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    \$\begingroup\$ @EmmettPalaima I'm not convinced that you sufficiently apprehend how the circuit works. If so, you would have written a relatively straight forward summary. I'm also not convinced that you are ready to design such a circuit. If so, you probably would have been able to provide us with a summary of the difficulties you anticipate and asked the question in a more informed and different way. Finally, because of your comment about rhythmically firing a lot of these without how you hope to achieve that nor details about what much be achieved, I'm worried this isn't the right tree to be barking up. \$\endgroup\$
    – jonk
    Jul 15, 2020 at 8:47

2 Answers 2

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Buy a fence charger for cattle. Plug in to 120v. You might fit it into your bug zapper. Basic unshielded wire to one connection (wire on fence line). Other connection to the ground rod. Could be used for free standing bug zapper grid when insect shorts them self out. The chargers pulse. You would have to hook up UV's separately

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    \$\begingroup\$ an electric cattle fence is not on continuously \$\endgroup\$
    – jsotola
    Sep 8, 2023 at 5:02
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That's a custom transformer made for that specific product to work with that specific circuit. Those are not "off the shelf" components and are made in large quantities (>100,000) for pennies a piece. You can't use just any "6-lead transformer" in a circuit like this because the transformer is tuned for the circuit - it's the heart of the oscillator.

Even if you designed the circuit your self, and knew the exact spec's you need for the transformer, the NRE is going to be at minimum hundreds of dollars. So your transformers are going to be pricy in small quantities. In other words, buying whole mosquito racquets will be much cheaper than spec'ing a customer transformer.

Personally, the circuit shown is very poor, very unstable, and difficult to get functioning properly. It's deceivingly simple looking.

A better idea would be to get HV generators for your application. As a compromise, the circuitry that generates the HV ignition in xenon flash cameras should get you in the ball park.

If you really want to tackle your own design, I would start with a 3-terminal high-voltage trigger transformer. Way easier to use and most simple oscillator circuits will run it, more so than the crappy bug zapper circuit which was designed to be as cheap as possible to the point where it can't be any cheaper.

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