Dear YIPLAn item of interest for readers: For $1.50 businesses and schools are equipping themselves with "dial-lock", which fits into the "1" position on a dial phone, which eliminates calls except from dial-lock key holders. (For pushbutton phones, a steel plate covers the buttons-Ed.) For every piggy action, there is an equal and opposite people reaction. Simply lift the receiver and rapidly push the buttons on the cradle equal to the numbers you would dial. For example, to dial 936-2323 you would push the buttons down (or just one of them) 9 times, 3 times, 6 times, etc., about as fast as a watch ticks, with a second or so between each digit. Keep count, cause its easy to loose count. Or, push the button 10 times, and you can give the operator the number you want, whether its around the corner or across the country. She is well-trained to assist you most ably. The "dial-lock ads are right, the phone bill is effectively reduced, but it doesn't say whose.
The Credit Card Computer we reported to you about is not yet available to all operators. So in some areas, the old system of simply matching the 4th digit to the letter still works. We've also heard that on the "West Coast, the computor is off from 2-4 a.m. for checking, and credit card calls during that time are assumed to be valid. The same thing is true in other areas, but we don't know the times. They may be the same.
(The terms "tip" and ring"(also "sleeve") come frorn the old manual switchboard days and describe the connections on a cord plug. These archaic terms are still used today: the tip> side is the green wire and L1 if things are hooked up properly; the ring side of the line is the red wire and L2.)
Second: I have constructed several Blue Boxes using the Signetics NE 566 IC. I do not recommend it for several reasons: 1. It is designed to be a voltage-controlled. oscillator and is very good in this role. It is so damned voltage sensitive that it needs a very stable, rock solid battery supply. Even with a zener regulator after the battery, which is getting rather silly, it is no good because of 2. its temperature sensitivity. Using mylar caps and metal-film resistors I got an 8% variation between 35°F. and 90°F., which means you have to re-tune the thing all the time. Finally, diode variations lead to unreal differences between tones that should be the same frequency. Best Wishes, T.V., Calif.