SU21246A1 - Instrument for measuring the duration of an echo - Google Patents

Description

The present invention consists in a special form of an instrument for measuring the duration of an echo (reverberation), for example in halls and studios.

In FIG. 1 shows a diagram of the device; FIG. 2 - a modified diagram of the device.

An artificial line is connected to the output circuit (contacts Oi, 0) of the microphone amplifier in series with a neon / L lamp. It consists of a variable capacitor C and a sectioned resistance R equipped with a HI switch. Pin 5 of this switch serves to discharge the capacitor. Resistance R is also connected to contact 1 of the three-contact key K, when it is closed, this resistance (via contact 2) is connected to the engine of potentiometer I, with one end connected to the amplifier circuit (contact O). The potentiometer is a closed battery E. The contacts 3 and 5 of the key K are connected to the loudspeaker G, and the contacts 4 and b to the sound frequency generator 3. The microphone and the loudspeaker of the instrument are installed in the room where the echo duration is measured.

Sound induced voltage

fed to a neon lamp with a slowdown, i.e. the lamp lights up alternating between the time the sound ceases. This moment is determined by closing (to the left) of the key K. If after a period of time after the sound ceases, the electromotive force of the microphone current is still large enough and E (, - eo E (i.e. equal to the lamp ignition voltage), then the value of this Voltage o can be easily determined. By knowing the magnitude of the voltage of the mic current through 7 CR seconds after the sound stops, so-called standard reverberation can be calculated. The neon lamp also serves to establish the initial amplitude (sound intensity).

The effect of the modified device (Fig. 2) is as follows. By means of switch D (switchable to the left), the reproducer G is disconnected from the generator 3 of the audio frequency and at the same time the voltage is applied to the relay P of slow-acting. However, the effect of an alternating voltage (from the remaining sound wave) on a neon lamp, which serves as an indicator, does not occur simultaneously with the loudspeaker turn off, but with some slowdown (respectively, R and C),

after which the relay P does not have its own measles and breaks the X circuit, shunting the secondary winding of the microphone amplifier transformer U. By adjusting the indicator to a certain sensitivity and changing the deceleration (resistance R and capacitance C plays the role of a “reverberation finder), it is possible to determine the instant of the lamp flashing under the action of the remaining sound wave. Then, using the values of C and / -determines the reverberation time. The device can be calibrated directly in seconds (up to three seconds). Potentiometer P serves for initial setting of the sound power.

The device can also be used to determine a short period of time (0.1 to 3 seconds), during which any damped electrical process or short-term pulse lasts.

The subject matter of the invention.

An instrument for measuring the duration of an echo, characterized by the use of an artificial line connected in series with a neon lamp into the output circuit of a microphone amplifier, so that when the lamp is ignited after a period of time after the sound ceases, where C is the capacitance and R is the resistance of the artificial line, judge the magnitude of the electromotive force of the microphone current.

2. Modification of the device described in Section 1, characterized by the use of a delayed relay P, the measles of which bypasses the circuit going from the microphone amplifier U to the NL neon lamp used as an indicator.

A.M.

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