Labels:text | black and white | diagram | font OCR: CONSTRUCTION The Blue Box uses two tones per digit. We AUCHBUT TOM HOW IT WORKS show ane oscillator and a common amplifier, both being turned on when the pushbutton sends .OX thru the diodes, one for cach of There are two basic types of telephone offices thru +1K 47K which all calls are switched. The first is the CO, the Ixo oscillators (for that hattons digit) LOS ANGELES 39Kl or Central Office. The wires from your telephone go NEW YORK mil one for the amplifier. So diodes are 15 K to your local CO. From there your call is switched AREA 213 used, or an on-oft switch on the amp Icts AREA 212 you use only "limitched silicon). The hest 02 to another telephone in the same CO, meaning a local TOLL speaker is a Telephone carpicce. Each tout call, or it is switched to a toll office. A toll of - ...
