Re: Of Mice and HV (fwd)

["High Voltage list" <hvlist@xxxxxxxxxx>]

Original poster: Steven Roys <sroys@xxxxxxxxxx>



---------- Forwarded message ----------
Date: Fri, 14 Apr 2006 00:46:52 -0400
From: Mike <mike.marcum@xxxxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Re: Of Mice and HV (fwd)

I guess it depends on what you consider "clean". I think it's going to be 
difficult to get guaranteed kills without filling the room with burning 
hair/rat meat smell. It would almost have to be high enough voltage to arc 
through the fur for it to be reliable I'd think. Maybe if the voltage were 
5-10kV but the discharge current limited to maybe a few 2-3A relatively 
quick pulses (a few mS) so it wouldn't be a smoldering mess/blown to bits 
but still defibrillated. A few 942c20p15k caps come to mind for this (those 
bite hard when charged to 3kV, never thought 675 mJ would hurt so much lol).

Mike
----- Original Message ----- 
From: "High Voltage list" <hvlist@xxxxxxxxxx>
To: "hvlist" <hvlist@xxxxxxxxxx>
Sent: Thursday, April 13, 2006 1:07 PM
Subject: Of Mice and HV (fwd)


> Original poster: Steven Roys <sroys@xxxxxxxxxx>
>
>
>
> ---------- Forwarded message ----------
> Date: Tue, 11 Apr 2006 07:20:03 +0930
> From: Matthew Smith <matt@xxxxxxxxxx>
> To: High Voltage list <hvlist@xxxxxxxxxx>
> Subject: Of Mice and HV
>
> Greetings All
>
> CONTENT WARNING: If you are distressed by nasty things happening to
> vermin (small furry creatures to those not infested with them), please
> do not read any further.
>
> They don't make 'em like they used to!  Our house, completed just over
> two years ago (actually not completed, but that's another story!)
> appears to have been built to accommodate rodents just as comfortably as
> humans.
>
> Snap traps have proved anything but reliable (bait gone, trap still set)
> and when they do operate, frequently kill in an unclean manner.
>
> So, I have decided to build an electric mousetrap.  Idea is simple:
> mouse enters trap and has to pass through a narrow gap between two
> aluminium plates arranged in a V.  (Mouse enters the larger part of the
> V.)  One plate is fixed, the other against light spring tension so that
> the subject has to push between the two plates to get to the bait.
>
> Plates are connected to a charged capacitor.  Charging will be from a
> PWM supply driven by a microcontroller which stops when capacitor
> voltage reaches an upper threshold and starts again once it has
> discharged (mostly through the feedback voltage divider) down to a
> minimum voltage.  The idea being that this device is battery-operated
> and tries to save power.
>
> Does anyone have any idea what minimum voltage I would need to apply to
> guarantee fatal fibrillation?
>
> I had considered powering from a disposable camera supply (no
> microcontroller - simply pulse the start button when the neon goes out)
> but, whilst photoflash capacitors can give us a ghastly bite, is the
> 300V or so enough to take out a mouse in its insulating fur coat?  I've
> serviced equipment before where mice have gone in a mains (240V) PSU and
> have blown the fuses but am still unsure about the certainty of a clean
> kill.
>
> Once I've got this idea working, I want to motorise it so that the
> defunct rodent can be cleared from the plates and the trap be readied
> for another "client".
>
> Cheers
>
> M
>
> -- 
> Matthew Smith
> IT Consultancy & Web Application Development
> http://www.kbc.net.au
>
>
>
>