The classic fish shocker was a hand-cranked telephone ring generator. Puts out ~100 volts at ~20Hz when cranked. They were a very common military surplus item, having been used for field phones. I recall seeing one advertised in the last year, although I was not looking.
A friend of mine in PA worked for the fish comish. for many years. He used to go out and do fish shocking to do population studies. They didn't kill only stun the fish but then could net and measure etc. I helped him with some of the electrical controls etc. Wadding a crick pulling a boat with a generator never sounded like fun to me. :-) ...lew...
From what I've learned so far, it looks like someplace in a range of 100 to
600 volts does the job. I see the commercial unit is pulsed DC. Apparently the field telephone is 100 volt hi frequncy AC.
So, would plain old house 110, or 220, likely work? Also it would be easy to step it up to 440 with a transformer. Or, if it should be DC, just add a rectifier.
"Karl Townsend" fired this volley in news:483adf37$0$210$ snipped-for-privacy@auth.newsreader.octanews.com:
Ideally, 90v @ 20hz. That's far from "hi frequncy AC".
We did some experimentation with various frequencies when I was diving with SubArc in Florida in the '60s. (freshwater only) Some fish are attracted by various frequencies up to low-audio. Some are repelled. Almost none will voluntarily swim into stun range of a continuous signal.
Most seem best stunned by DC pulses or low-frequency AC. The range ain't far. A fish that will be thoroughly stunned four feet from the electrodes won't be fazed eight feet away (but will react to the shock by going away from it). Apparently, they possess the ability to discern the direction from which the shock is coming.
Talking of mil-surplus, my father and his fellow squaddies in the UK Royal Engineers used to fish in Ireland during WW2 using gun-cotton. He was there looking after the mustard gas (which of course we didn't have), he also trained special forces in demolition. Apparently, a standard slab of gun-cotton (about the size of a paperback book) left hanging in the flue of the stoves used in the army huts was the usual way of showing one's displeasure with the occupants.
Well, you may still want to keep it in mind. You'll do well to get some homemade electric shock system together and working right in less time.
They use electric shock around here for counting fish. My impression is that it's kind of a big ordeal. I saw them use it once on the Millstone River and it was not a simple setup. Of course, they were doing something a little different.
If you want me to try and contact him and get the particulars I'll see if I can. Dont have an e-mail for him right now but could try a phone call. I don't comunicate well on a phone. (hearing is bad) ...lew...
I LIKE THAT. I don't have a plasma. I'm telling Julie, "Don said I got to have a plasma to clean up the fish pond for you". It would work, but I just got a HUGE milling machine. Conversation around the table is now focused on what would be the best new flooring for the kitchen. I know better than to start talk about my next toy before this is done.
This may be a dumb question and eliminate the fun of building a fish stun gun, but wouldn't it be simpler, easier and more desirable to mostly drain the pond, sweep the flopping fish to one low spot with a broom and then sort out the keepers? You should probably be restarting with a sizable water change anyway, and if you really wanted, you could pump the water into a holding tank(s) for later return.
I should pint out that very little rotenone will kill an entire stream. It has happened a few times in British Columbia.The stuff is just a the ground up leaves of a South American plant, and is safe for humans. You don't want to have the stuff getting into fresh water streams.
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