Most mopeds do not have a battery, so the electricity is all AC alternating current. Some mopeds and almost all motorcycles have a battery, usually 12 volt. Their electricity can be all DC or part DC and part AC. An incandescent light bulb works the same on AC or DC, but a horn is made for either AC or DC. DC current horns go beeeeeeeep, like a little cute car horn. AC horns sound like the buzzer when you get a wrong answer on a TV game show. AC horns also sound like duck callers. The pitch goes up with the rpm of the engine. They’re not much louder than the engine. It is difficult to sell used or new old stock AC horns that were made 35 years ago. If they haven’t been kept in a sealed wrapper, then they might not work good, even though they’re new. It’s because corrosion can get on the aluminum plate. Furthermore, you cannot easily tell whether a horn is good or bad. You cannot easily look inside because it is riveted together. You cannot perform a valid test of it unless you have the moped it is intended to go on, running, with working horn wires and button. Because the AC an vary from one kind to another, and from a new one to an old one of the same kind, you never know if a horn that works on a Peugeot for example, would work on a Puch, until you try it. Or it might work good on Puch at low rpm, but not high. Maybe visa versa on Garelli. It also matters whether the head light is off or on. Many AC horns will not work, or are not loud, unless the headlight is off. Myrons Mopeds has some 6V AC horns, but they are only offered when the running good moped is present in the shop and able to easily attach the horn to test it. The price is usually $20-25 for a good used AC horn. All modern scooters and motorcycles have 12 volt DC horns. They are common. Some older Taiwanese mopeds have 6 volt DC horns. AC buzzers are “old school” and are not on anything modern. So there are no known freshly made replacements.