Recently I got tired of constantly having to change batteries to my Zapper.
Do you think it is possible to use an AC/DC transformer, which transforms the voltage from 220V to 9V, and also changes the current to DC? That is what I did, but I am not sure if the Zapper works as well. The AC/DC adapter probably does not change the current to a smooth DC-flow, but rather a "pulsed" DC-flow.
Is there any expert on Zapper-electronics that would know this kind of stuff?
I vaguely understand the intracantcies (sp) of electricity. I can not comment on the waveform here between battery vs transformer however after many hours using both, I simply can not differntiate any different effectiveness between the 2 power supplies. There may be other implications worth considering (however I really dont).
If you like living, then I would not use any wall transformer that is not rated "safe for use in medical equipment designed for human contact". Such transformers will cost at least $100.00 US.
Any power supply or transformer is subject to surges, breakdowns, or other failures and I for one would not want to be on the receiving end of 110 volts much less 220 volts!
I have heard that there have been deaths reported to the FDA from such occurences.
Ken, well done. Do you see where I said "There may be other implications worth considering ". This is the "implications" that I quietly made reference to. I have seen this very subject debated by some pretty big heavy weights. And I use a wall transformer for my equipment. The suggestion you make is a good one, albeit expensive. But life is worth it. Hulda has a couple of suggestions as well. And we can discuss the impact a transformer has on resulting waveshapes. This can be a very in depth discussion as I have seen it on the beck and stuff forum with alvin rose, bob the moderator of microelectricitygerm killer, V and many others. It was a very strong debate and included an electrician. Doesn't matter, you have a good suggestion.
Guess we better start suggesting some of these heavy weight fg, etc equip designers change their transformers. You know whats out there.
The output voltage of most wall-warts (those ubiquitous black plug-in power supplies) is unregulated and poorly filtered. For example, a device marked "9VDC, 0.25A" will make 11 or 12 volts, pretty clean, with no load, and around 9 volts, but with noticeable ripple, at full load. Not great, but it will have almost zero effect on the output of most Zapppers. Why? Because Signetics designed the 555 timer circuit, the heart of most Zappers, to reject power supply variations. So while the Zapper output voltage level will vary proportionally with the power line voltage, the output frequency (and harmonic content) will remain remarkably stable.
Beyond portability, even a cheap AC supply is superior to most battery systems. Besides amplitude stability (no output droop as the battery voltage fades), the output impedance also does not change with time. ALL battery chemistries dictate that the output impedance of the battery increases as the battery discharges. This leads to a small frequency drift and larger output voltage droop.
If you want to buy one rather than use one laying around, get one of the adjustable or universal ones from Radio Shack. These have a regulated output; more stable and less ripple. Better.
Can the transformer "type" (construction?) affect the circuit output "quality"? Yes, but only if the designer is a bozo.
Finally - safety. The US consumes 100 million wall warts per year. Yup, one new one for every 3 people in the country, every single year. The most conservative estimate I've seen says there are a billion in operation at any given instant. Even if 1000 failed in a life-threatening manner (and they don't), that's million-to-one odds. Thanks to the steady advance of European safety agency rules, there is almost no difference between medical and non-medical small transformers. The difference between the two types of complete power supplies relates more to ground current (microamps vs milliamps) than to breakdown voltage or creepage distance. These are covered by UL 544 and 1950.
Who am I? Electrical Engineer, analog circuit and power supply designer for 30+ years.
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Connecting a Zapper to a AC/DC-adapter 
