Labels:text | diagram | pattern OCR: MORE BOX PLANS Correction- The 39X resistor used for setting the gain of the amplifier in last month's is- sue is incorrect. It should be between 5 and 6 thousand ohms' in value. Too large a value will cause a buzz in the amplifier from too much gain. Let's clear up a few details in last month's Blue Box construction plans. For those of you without a lot of test equipment, this might help you a bit. A pure sine wave, from a Twin T oscillator, and 1- The Twin T oscillator has maximum stability for from : touch tone phone, is the best waveshape . voltage and temperature changes when it is tuned for activating Western Electric's brain. at least 5% above the initial oscillating frequency of the oscillator. Otherwise, a voltage drop of a volt or temperature drop of 20 degrees might turn it off. ...
