## Time Travelers Caught On Toefl Speaking

1 For ensuring the set quasiresonance frequency (¦ =2 kHz) (according to a formula for RC generator quasiresonance frequency - R1=R2, C1=C is chosen, the R1=820 resistor of Ohms (from a number E2 of the MLT-2 type Proceeding from a formula (the K53-3 type

At in the device there are self-oscillations which frequency is defined by a formula. Usually use in a frequency-dependent branch of Vina R1=r2=r, C1=c2=c Bridge, and the frequency of self-oscillations: and self-oscillations arise provided that coefficient of strengthening of the amplifier consisting of OU and R3, R4 resistors, more than three, in other words, the condition has to be satisfied

In the ranges low, sound and radio frequencies as resonant chains and components apply RC chains, LC contours, quartz resonators, electromechanical oscillatory systems (for example, tuning forks, etc.)

The R1 resistor provides initial shift of the compound VT1, VT4 transistor, and the of C1 prevents emergence of a parasitic. For providing the set output current of P compound VT1, VT4 transistors there have to be not less than 400 W. The protective R3 resistor limits output current of OU in case of short circuit at the exit. Decrease in level of pulsations of output tension is provided with the condenser C