How does a dollar bill changer work?
Creating a good bill changer is a tough problem. The device has to work with all sorts of bills, from crisp new ones to ragged old ones, and it has to be reasonably good at telling real bills from fakes. In many cases, the changer also has to be able to sense the denomination of the bill. In order to accomplish these tasks, dollar bill changers use a variety of technologies. Several different patents listed below discuss techniques that people have employed. Some of these techniques have changed over the years as microprocessors have allowed more capability in the device. Here are several of the techniques that have been tried: A good bill changer will use several of these techniques because people seem to have a very strong desire to outwit bill changers. If you read the patents listed below, you will find that they handle such things as people inserting just half of the bill, people inserting bills with strings attached so they can jerk them back out, people who try unplugging the ma
