Re: Switch-mode supply for bug zapper (fwd)

[<sroys@xxxxxxxxxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 22 Sep 2004 09:20:20 -0600
From: Gomez Addams <gomez@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Switch-mode supply for bug zapper (fwd)


On Sep 22, 2004, at 7:40 AM, High Voltage list wrote:

> Original poster: <sroys@xxxxxxxxxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Wed, 22 Sep 2004 12:18:49 +0930
> From: Matthew Smith <matt@xxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Switch-mode supply for bug zapper
>
> Hi All
>
> Unsatisfied by the performance of our bug zapper (UV tube, HV applied 
> across a
> grid - flies crawl in, then crawl out again without shorting 
> anything), I am
> looking at alternative designs.
>
> The one we have uses a conventional laminated iron, 50Hz transformer.  
> The whole
> thing gets warmer than I'd like, so I'm looking at making a switchmode 
> version.
>
> My idea is to use a flyback topology (only two windings to wind) with 
> an
> integrated switcher (TOP202), which runs at 100kHz.  This will drive a 
> 1:10
> transformer, which will be rectified and charge a small capacitor.

You could probably just drive an old flyback transformer with a simple 
transistor
circuit (circuits abound on the web for this) and skip winding your own 
transformer.

You can also use the rectifier from a TV set for the output.  Half 
wave, but who
cares about efficiency for this thing?  the power required is pretty 
small.