Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!cwjcc!hal!nic.MR.NET!ns!logajan
From: logajan@ns.network.com (John Logajan)
Newsgroups: sci.electronics
Subject: Re: HIGH VOLTAGE STUN GUNS'S
Message-ID: <1449@ns.network.com>
Date: 13 Jun 89 23:31:42 GMT
Sender: logajan@ns.network.com (John Logajan)
Organization: Network Systems Corp. Mpls MN
Lines: 34


In private e-mail, someone wrote:
> at 9V you are not going to get 75KV at 25KW, even for a short duration.

Well, I see that they sell 9v batteries that can sustain 500mah @
7.2v average, which is equal to 3.6 watt-hours or 12960 watt-seconds.

Thus, a 9V battery can (in principle) produce 26000 watts for 1/2 second.

Let us assume that we can only get 1/100 (1%) of this power in a
single blast.  That is still 5 milli-seconds at 26000 watt.

I don't have the capacitor energy equation handy, so I don't know the
size required to hold the above case, i.e. 130 watt-seconds @ 75KV.

But, can we even tap the energy of the capacitor in 5ms ?

Well, recall that the resistance of the load is on the order of
220,000 ohms.  So even if the series inductance was huge, i.e.
1 henry, the pulse shape would reach max voltage in 1/220,000 * 5
seconds, or about 25 micro-seconds.

Thus even at extremely high levels of inductance, we see that the
rise time is insignificant compared to the "energy" discharge time.

Hmm, working backward for the discharge time of 5ms and 220,000ohms
I come up with a capacitor somewhere between .02 and .1 micro-farads.

This is fairly large for 75kv and so it might be a wee bit heavy to
haul around in a stun gun -- but I am not sure of that either.

-- 
- John M. Logajan @ Network Systems; 7600 Boone Ave; Brooklyn Park, MN 55428  -
- logajan@ns.network.com / ...rutgers!umn-cs!ns!logajan / john@logajan.mn.org -