If you bet that the brain of this system is a computer, you are right. The microprocessor built into the machine does the same thing a human teller does in a bank. It identifies the customer, checks whether there is enough balance to withdraw the money, transmits information on the requested amount and authorizes the release of money. And most important: like a good employee, he has several mechanisms to ensure that the customer receives the exact amount of money, not a cent too much or too little.
Even so, despite the fact that the system has a relatively low number of failures, they do happen. And then there’s the biggest headache. If you are unlucky enough to receive too few bills, you will only be reimbursed if you can prove that this happened (when the branch is still open, the easiest way is to notify a bank employee right after the withdrawal).
But, if you leave with an extra huff, who will pay the difference is the employee responsible for replenishing banknotes (since it is almost impossible for two banknotes to come out together, the biggest source of errors is human error, when someone puts 50 reais bills in the compartment that holds 10 reais banknotes, for example).
The first ATMs (also called ATMs) were created in the 1930s, but the system only became efficient and safe in the 1960s. From then on, these machines invaded banks.
In recent years, however, they have fallen into disuse. According to the 2018 FEBRABAN Banking Technology Survey, carried out by the Brazilian Federation of Banks, bank transactions are currently carried out mainly via the internet and mobile phones.
To give you an idea, of the total transactions carried out in 2017, 57.7% occurred through these platforms; while only 13.7% were given directly at the cashiers.
path of banknotes
1. Withdrawal at an ATM begins when the customer places the card in the magnetic reader. The stripe on the card holds the account number and the agency number. The reader receives this information and transmits it to a processor, which grants access to the machine if the customer enters the correct password.
2. If the password is correct, the ATM accesses the customer’s account to check the balance. To know how to establish this communication, the teller connects to the bank’s server through a telephone line. If there is enough money, the server sends an electrical signal to the cashier authorizing the withdrawal.
3. From then on, the brain of the entire system, the cashier’s processor, runs the rest of the operation. With the withdrawal authorized by the bank, he triggers the mechanisms that will deliver the banknotes to the customer.
4. The money is inside metal drawers, each with a different value of bills. Each drawer holds between 2,000 and 2,200 bills. When withdrawing, a system of rubber straps removes one bill at a time from inside the drawers until the requested amount is totaled.
5. Before being released, the banknotes pass through an optical sensor that searches for possible errors — it can identify two notes stuck together, for example. If they pass more banknotes or of a different value, they are diverted to the rejected banknotes drawer.
6. Once delivered, the money is debited from the current account. If the customer asks for it, the processor sends an order to the machine’s built-in printer and it issues a receipt for the transaction.