Audio circuits

Rubra activated the audio circuit on in the shop s net processor. "Out " he commanded. 

Standard load Refers to the resistance of a load that is a standard estabhshed by an organization or committee commissioned to decide standards. Input, output, and interstage resistance in RF circuits is estabhshed to be 50 unbalanced. Input, output, and interestage resistance in video circuits is estabhshed to be 75 Si unbalanced, and that for audio circuits is 300 S2 balanced and sometimes 600 S2 balanced or 8 Si unbalanced. 

Measurements are made on audio circuits and equipment to check performance under specified conditions and to assess suitability for use in a particular application. The measurements maybe used to verify specified system performance or as a way of comparing several pieces of equipment for use in a system. Measurements may also be used to identify components in need of adjustment or repair. Whatever the application, audio measurements are a key part of audio engineering. 

When the connector is used to make connection in an audio circuit, the configuration can be essentially the same. The additional consideration is that the material have low loss dielectric at the frequencies to be transmitted and that the spacing of the contact elements be determined by the transmission line characteristics required. Spacing is an electrical design function and its determination re-... 

To warn of an unfavourable operating condition by the use of an audio-visual alarm or trip or both, schemes can be introduced in the control circuit by means of a temperature detector or other devices to monitor any or all of the following internal conditions of a motor ... 

Water-Cooled motors, type CACW (cooling type ICW 37 A 81 or ICW 37A 91) (Section 1.16, Table 1.12) should be fitted with moisture detectors to provide an audio-visual alarm in the event of a leakage in the water circuit or a higher coolant temperature. 

These are meant to be used with a capacitor to tune a filter circuit, with resonances in the audio frequency range for reducing and filtering the harmonics or communication frequencies. They provide a near short-circuit for the required harmonics to filter them out of circuit. They may be single-phase or three-phase and connected in series or parallel of the capacitor circuit and may have a fixed or variable reactance, rated continuously with saturated magnetic characteristics. They may incur heavy losses. 

The square law relationship also implies that the instrument measures RMS values. It can be used on either A.C. (up to the lower audio range if special compensating circuits are employed) or D.C. The instrument reading can be... 

Figure 1. Circuit diagram showing a fine-frequency control for a Hewlett-Packard 200 AB Audio-oscillator.

Apparatus. All electrical resistances were measured with an electrolytic conductivity bridge (Leeds and Northrup model 4666) which was constructed according to specifications set forth by Jones (28) and described by Dike (29). The audio-frequency source was a General Radio Co. type 1311-A audio oscillator used with the frequency regulated at 1000 Hz and the output at about 5 V. The detector circuit consisted of a high-gain low-noise tuned amplifier and null detector (General Radio Co. type 1232-A) and an oscilloscope (Heathkit model O-ll) ... 

The crystals are placed between the plates of a condenser which forms part of an oscillating circuit. An audio-frequency amplifier, with headphones or speaker, is connected to the oscillator. When the frequency of the oscillator is changed continuously by means of a variable condenser in the circuit, clicks (or, for a large number of small crystals, rustling noises) are heard. The reason is that whenever the frequency of the oscillator happens to coincide with a natural frequency of one of the crystals, there is a sudden change of current through the condenser and consequently an impulse which is amplified by the audio-frequency amplifier. For a suitable circuit see Wooster (1957). 

Lidbetter, 1983] Lidbetter, P. S. (1983). Signal processing for the digital audio console. In Proc. 6th European Conf. on Circuit Theory and Design, pages 536-539. 

Radio-bridge — A bridge circuit similar to the - audio-bridge except the signal source produces frequencies in the radio frequency range (e.g., 50 kHz-50 MHz) and a radio receiver (or even an oscilloscope) is used to determine the condition of null. 

Fig. 40. Block diagram of measuring circuit. P, potentiometer L, load inductance R, small resistance D, dual scoper O, audio frequency oscillator A, sawtooth wave generator B, tuned amplifier K, oscilloscope equipped with amplifiers Q, gain control of cathode follower to read Q...

One way to do this is to use pressurized enclosures for electrical components. They maintain a slightly higher pressure inside than the atmosphere outside them, so if a leak does occur in the enclosure, it will vent outward and will not allow a flammable hydrogen and air mixture to go inside. If the pressure inside falls below a certain point, an alert occurs and the system is shut down. This can be done in different ways depending on the circumstances. Most systems have an audio alert as well as a visual indicator such as a blinking LED. In addition to this, upon loss of pressure a circuit will immediately disengage the power supply to any circuits and electrical devices within the enclosure, and the system will be shut down automatically. If you have an experimental device that is constantly attended while in the operation, a simple cutoff switch that is operator activated and approved for hazardous atmospheres will suffice. 

There are several ways to pressurize enclosures. One is to apply a slight positive pressure to the enclosure and then seal it with a valve cutoff. Such a system would have a pressure read-out, or audio-visual alert, and a cutoff circuit. With this method a good seal and regular monitoring is necessary because the unit will probably have to be re-pressurized periodically to keep it at proper pressure, as very slow leaks can occur over time. Usually, this method is used when attendants or operators are present. 

And all over the place Printed circuit laminates Audio and video tapes Adhesives Antifreeze Telephone poles Roadmarkers and paints Fishing nets, ropes, and string Fish and vegetable boxes Horticultural him Powder and liquid detergents Dry cleaning huids Disposable syringes Contact lenses... 

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