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

[<sroys@xxxxxxxxxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 22 Sep 2004 23:04:36 +0800
From: Peter Terren <pterren@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Switch-mode supply for bug zapper (fwd)

Do you have to rectify it to zap bugs?  If you need DC to charge a 
capacitor, perhaps use a flyback diode or just use a standard TV flyback 
with integral diode.
Peter

> From: Matthew Smith <matt@xxxxxxxxxx>
> 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.
>
> 1) What do I need to know and what formula would I use to calculate my 
> primary
> turns?
>
> 2) Ditto for sizing the components for the snubber.
>
> I assume that a microwave oven diode - normally working at 50-60Hz - would 
> be
> too slow for the HV rectification and that I'd need a string of high-speed 
> diodes.
>
> Cheers
>
> M
>
>
> -- 
> Matthew Smith
> Kadina Business Consultancy
> South Australia
>
>
>
>