Canadian Agricultural Products. To check for restrictions on fruits and vegetables from Canada, you can search the FAVIR database at www.aphis.usda.gov/favir/. Click the âFresh Fruit and Vegetablesâ link to the right to learn how to use the database.
The standard voltage for the telephone system is 48 volts DC. Ringing voltage is much higher, around 90 volts AC at a low frequency. When you place a load of about 600 ohms on the line, you are off hook or connected. Telephone ringer voltage is 50.5 volts at standing and -50.5 volts at ringing.
The voice parts of the telephone are in the handset, and consist of a transmitter (often called microphone) and a receiver. The transmitter, powered from the line, puts out an electric current which varies in response to the acoustic pressure waves produced by the voice.