I've written before about AC adapters, their safety, and their electronic characteristics. Short form - I'm a fan. I've also written about sloppy science, the UZ website, bad writing, and how they do more harm than good. That's why things like this:
"And as the battery discharges the square-wave changes, developing echoes..."
bother me. "echoes"???
What are these "echoes" and why can't I hear them. Oh, that's right, a zapper is not an acoustic device. Increasing source output impedance which fails to swamp out reflected energy from a non-characteristic impedance load, maybe; but: "echoes"?
"...that further reduce the zapper's effectiveness."
Since CZ has at least TWO forums (?) to debate a Zappers effectiveness under any conditions, a completely unsupported statement such as this is nothing but a scare tactic. Scare tactics are excellent marketing tools, right up until people see them for what they are.
I did some digging. Radio Shack used to sell a universal battery eliminator that had the correct connector to replace a 9 volt battery, but they no longer sell it. Other people sell a similar model, but without the 9 volt connector. Bummer. If anyone is interested, I can post where/what to buy to make up one without any soldering, just wires and tape. Round numbers, $10, about 5 for parts and 5 for shipping.