Amplifier

“ If there were another type of generator, for undamped waves, as efficient as the audion, and if the beat effect produced by the generator were utilized on an ordinary detector circuit as sensitive as the ordinary audion receiver circuit. would this circuit be as sensitive and satisfactory as an Armstrong circuit?
What is meant by “increase in audibility”—an amplifier concern claims to have an instrument that increases the audibility 1500 times. ”

“ In the various Armstrong circuits, the increase in strength of signals is due to amplifying effect as in the ordinary amplifier rather than the heterodyne principle. Of course, in the Armstrong circuit, these two effects are combined, but the real increase is due to amplification. ”

“ A Regenerative Audio Frequency Amplifier Receiving Set.--The use of amateur regenerative cascade audio frequency receiving sets is getting to be quite common. To get the greatest amplification possible with amplifying tubes you have to keep a negative potential on the grids. You can, however, get very good results without any special charging arrangement by simply connecting one post of the rheostat with the negative terminal of the filament and connecting the low potential end of the secondary of the tuning coil with the - or negative electrode of the A battery. ”

“ He thinks 'em up, I build 'em. He busts 'em, I fix 'em. And when he gets into a jam, I'm the guy comes to bail him out. Like, for instance, this last gadget of his. Nothing dangerous about it, but it could have got him sunk in the river with his feet in a block of cement. It all started with an amplifier.
I found the diagram in the mail when I came into the shop one morning. Looked like an ordinary audio amplifier at first sight, and I started laying out a chassis. Picking out parts, I noticed something; even Bill can make a mistake sometimes. ”

“ The receiving system at Pioneer Site is also equipped with a low-noise, extremely sensitive installation combining a parametric amplifier and a maser. The parametric amplifier is a device that is “pumped” or excited by microwave energy in such a way that, when an incoming signal is at its maximum, the effect is such that the “pumped-in” energy augments the original strength of the incoming signal. At the same time, the parametric amplifier reduces the receiving system’s own electronic noise to such a point that the spacecraft can be tracked twice as far as before. ”

“ The times 12 multiplier and power amplifier consists of a buffer amplifiers, times 4 multiplier, power amplifier and times 3 multiplier which increase the carrier frequency and power to the desired output values. ”

“ An efficient multi-stage amplifier for radio-frequencies is difficult to build because of what we call “capacity effects.”
Consider for example the portion of circuit shown in Fig. 127. The wires a and b act like small plates of condensers. What we really have, is a lot of 243 tiny condensers which I have shown in the figure by the light dotted-lines. If the wires are transmitting high-frequency currents these condensers offer tiny waiting-rooms where the electrons can run in and out without having to go on to the grid of the next tube. ”

“ Where either a radio frequency transformer, that is one without the iron core, or an audio frequency transformer, that is one with the iron core, is used to couple the amplifier tube circuits together better results are obtained than where a high resistance grid leak is used, but the amplifying tubes have to be more carefully shielded from each other or they will react and set up a howling noise in the head phones. ”

“ The use of vacuum tube or electron tube amplifiers is so widespread that it is unnecessary to explain their operations here in any detail. It is important that the principle of amplification be understood, however. The input or information wave causes the grid to act as a sort of faucet as shown in Figure 6. That is, it controls the flow of electrons (the current in the circuit) from cathode to anode. A weak signal can therefore cause a similar, but much stronger, signal to appear in the circuit. The larger signal is subsequently used to power a loudspeaker in the radio set. ”

“ The scheme actually proposed only recognizes 21024 distinct states of compression of the water medium, these being sequences of 1024 pulses of two different sizes, one of which will probably be zero. The amplifier at the end of the line always reshapes the signal to bring it back to the nearest ideal signal. ”

“ Bill must've felt the same way. He was excited by now. "Shrimps and sweet cream for you, Tommy!" he shouted at the cat. Turning to me, he exulted, "Now I've got a real idea! Look, Mike!"
He grabbed a scratch pad and started drawing a new schematic. "See? We'll take the output of the amplifier and run it through a mixer-oscillator stage. That way, we can get a beat between a fixed frequency and the supersonic output of the amplifier. The beat should be in the audible range and we will be able to hear it; we won't need the 'scope. I want to hear what the cat is saying." ”

“ Mirrors, or adding machines? You can't make an audio amplifier of a three million gain."
"I know it—at least not a practical one. But, we can probably use our audio modulator to modulate a radio frequency, and then modulate the driver with the RF. Then we hang a receiver onto the detector gadget here, and collect RF, modulated, just like a standard radio transmission, and amplify it at RF, convert it to IF, and detect it to AF. Catch?" ”

“ When listening-in to distant stations the energy of the received wireless waves is often so very feeble that in order to hear distinctly an amplifier must be used. To amplify the incoming sounds a vacuum tube made like a detector is used and sometimes as many as half-a-dozen of these tubes are connected in the receiving circuit, or in cascade, as it is called, when the sounds are amplified, that is magnified, many hundreds of times.
The telephone receiver of a receiving set is equally as important as the detector. ”

“ Given a chunk of cold steel of goodly mass and tune your alloy disk to pure steel, and you can get a few micro-microamperes output if the tube is pointed at the object."
"Sounds interesting. How much amplification do you need to get this reading and how do you make it tick?"
"We run the amplifier up to the limit and then sweep the tube across the object sought, and the output meter leaps skyward by just enough to make us certain of our results. Watch!" ”

“ The human mind does not need an amplifier, as the radio receiving set does. Rather, it acts as its own amplifier, once having received the thought. I invented one, however, to prove that it could be done. I equipped Heinrich with it and in half an hour by suggestion reduced him to his present state of docile stupidity. I have, Mr. Parker, the means of moving people to do my bidding!" [207] ”

“ The reason a vacuum tube detector is more sensitive than a crystal detector is because while the latter merely rectifies the oscillating current that surges in the receiving circuits, the former acts as an amplifier at the same time. ”

“ A trigger circuit, which is shown as an ellipse, differs from a limiting amplifier circuit in that once the inputs have reached the threshold so that it emits one pulse, it will continue to emit pulses until it receives an inhibitory stimulus. ”

“ It's possible to be dealt a royal flush in a hand of cards, but it isn't very common. It's just as possible for a bunch of simpletons to set up an organization for one purpose, and have it turn out to be a supercharged, high-frequency k-factor amplifier. ”

“ For instance with a wireless telephone transmitter where an amplifier tube is used to set up the oscillations and which is made for a plate potential of 100 volts, distances up to 10 or 15 miles can be covered.
With a single 5 watt oscillator tube energized by a direct current of 350 volts from either a motor-generator or from a power transformer (after it has been rectified and smoothed out) speech and music can be transmitted to upwards of 25 miles. Where two 5 watt tubes connected in parallel are used wireless telephone messages can be transmitted to distances of 40 or 50 miles. ”

“ High-grade regenerative sets designed especially for receiving amateur sending stations that must use a short wave length are built on the regenerative principle just like those described in the last chapter and further amplification can be had by the use of amplifier tubes as explained in Chapter IX, but the new feature of these sets is the use of the variocoupler and one or more variometers. These tuning devices can be connected up in different ways and are very popular with amateurs at the present time. ”

“ It charges itself with space-resonant energy that does not leak off—sort of like a high-capacity condenser of excellent power factor. You can charge it to lethal dose and it may remain so for hours unless it is discharged."
"Why don't they discharge these, then?"
"It takes too long for them to load when they fire 'em up," explained Virginia. "Usually they remain at high charge between 'off' periods."
Ed Bronson looked into the amplifier with a wry glance. "A little knowledge is a dangerous thing," he grunted. ”

“ It simultaneously addresses all persons in the launch complex and operates as a public address system. The VSS equipment bay contains a monitor speaker and volume unit meter panel, patch panel, power supply, power control panel, switch panel, two preamplifier and three audio power amplifier units. One preamplifier and two audio amplifiers operate at all times. One audio amplifier is for above ground speakers and one for below ground speakers. ”

“ An audio signal, from the microphone in the helmets or lightweight headsets, is amplified by two microphone amplifiers and then applied to the MODE switch. With the MODE switch in the HF position, the output of the microphone amplifiers is applied to the hf transmitter. When the MODE switch is in the INT position, the output of the microphone is applied to the four headset amplifiers, via the two INT volume controls. With the MODE switch in the HF position, the output of the microphone amplifiers is applied to the uhf transmitter. ”

“ Each unit has a multipin audio and power connector, and a coaxial connector.
Electrical Characteristics: The uhf voice transmitter/receiver consists of a transmitter, receiver, and power supply.
The transmitter consists of a crystal controlled oscillator, two rf amplifiers, a driver, and a push-pull power amplifier. All stages except the driver and power amplifier are transistorized. The transmitter is fixed-tuned at 296.8 mc and is capable of producing an rf power output of 3.0 watts into a 50 ohm resistive load. The transmitter is amplitude modulated by a transistorized modulator stage. ”

“ You will get better results if you can afford another iron-core transformer. If you can, buy one which will work between the plate circuit of one vacuum tube and the grid circuit of another similar tube. Then you will have the right equipment when you come to make a two-stage audio-frequency amplifier. If you buy such a transformer use the other transformer between plate and telephones as you did before and insert the new one as shown in Fig. ”

“ It is built on exactly the same lines as the experimental transmitter just described, but instead of using a 100 volt plate amplifier as a makeshift generator of oscillations it employs a vacuum tube made especially for setting up oscillations and instead of having a low plate voltage it is energized with 350 volts.
The Apparatus You Need.--For this transmitter you require: (1) one oscillation transformer; (2) one hot-wire ammeter; (3) one aerial series condenser; (4) one grid leak resistance; (5) one chopper; (6) one key circuit choke coil; (7) one 5 watt vacuum tube oscillator ”

“ With a small loop made by ten turns of wire separated by about a quarter of an inch and wound on a square mounting, about three feet on a side, you will usually require two amplifiers. One of these might be used to amplify the radio signals before detection and the other to amplify after detection. To tune the loop for broadcasts a condenser of about 0.0005 mf. will be needed. The diagram of Fig. 100 shows the complete circuit of a set with three stages of radio-amplification and none of audio. ”

“ The estimate, of course, included the receiving set and two amplifiers, the aerial, and all the work of wiring, and supplying plugs, insulators, blocks, switches, etc., together with the necessary accumulators and batteries. ”

“ Shows that when the atoms become negatively and positively charged a condition of unbalance exists, and the resulting flow of electrons, which tend to restore a balance, can produce usable energy.
© De Forest's Training, Inc.; 1Oct48; MP3900.
ELECTRONIC TUBES. De Forest's Training, Inc., c1948. 100 ft., b&w, 16mm. (Radio Electronics. Reel lesson 8)
Summary: Actions, functions, and characteristics of the vacuum tube. Shows that since the changes of grid voltage can be duplicated only by larger changes of plate voltage, the triode tube acts as an amplifier. ”

“ In the regenerative circuit the tube is performing two jobs at once. It is detecting but it is also amplifying. [9] By “amplifying” we mean making an e. m. f. larger than it is without changing the shape of its picture, that is without changing its “wave form.”
To show just what we mean by amplifying we must look again at the audion and see how it acts. You know that a change in the grid potential makes a change in the plate current. Let us arrange an audion in a circuit which will tell us a little more of what happens. Fig. 93 shows the circuit. ”