Sunday, October 24, 2021
Sunday, July 29, 2018
THREE (3) WAYS TO DETECT INFO IN A RADIO WAVE.
July 30, 2018
Two more days and it will Ghost Month, August.
Good morning to ALL.
Well, please see the topic. I wrote about this last week but it did not get saved , so I lost it. I say 3 but not only 3 ways. This is just observations from research and projects.
1. Diode Detector
Probably the oldest and also most used in a long time. Crystal set and superhets. They use diode to "detect" the sound. See AM radio. The RF which is DC is rectified to DC.Since the modulation was amplitude, the DC fluctuates in accordance with the sound.
2. Current Sense
I coined this description. It is called regenerative but actually, it a low power oscillator as a receiver.
Toy walkie talikie is a fine example. One tranny is made to oscillate very low power. A dropping resistor is used to lower the rail voltage, usually 9 volts. Any radio signal of the same frequency suppresses the oscillation and the current draw from the battery changes. The resistor acts like a ballast. The current changes reflects the amplitude change of the received signal. Thus, the audio is heard.
3. Direct Conversion.
The Crystal set radio can be described a DC radio since it dos know go to converting the RF before the diode. In a superhet, an intermediate frequency is created. In a regular commercial AM radio set, a ocal oscillator provides a frequency 455 Khz above the incoming signal. Mixing the frequencies results to leaving the IF 455 Khz which is amplified then detected.
In a DCR (Direct Conversion Receiver), no diode is used. a mixer down-verts the frequency to the audio range. So, it converts RF to AF directly by mixing.
Two more days and it will Ghost Month, August.
Good morning to ALL.
Well, please see the topic. I wrote about this last week but it did not get saved , so I lost it. I say 3 but not only 3 ways. This is just observations from research and projects.
1. Diode Detector
Probably the oldest and also most used in a long time. Crystal set and superhets. They use diode to "detect" the sound. See AM radio. The RF which is DC is rectified to DC.Since the modulation was amplitude, the DC fluctuates in accordance with the sound.
2. Current Sense
I coined this description. It is called regenerative but actually, it a low power oscillator as a receiver.
Toy walkie talikie is a fine example. One tranny is made to oscillate very low power. A dropping resistor is used to lower the rail voltage, usually 9 volts. Any radio signal of the same frequency suppresses the oscillation and the current draw from the battery changes. The resistor acts like a ballast. The current changes reflects the amplitude change of the received signal. Thus, the audio is heard.
3. Direct Conversion.
The Crystal set radio can be described a DC radio since it dos know go to converting the RF before the diode. In a superhet, an intermediate frequency is created. In a regular commercial AM radio set, a ocal oscillator provides a frequency 455 Khz above the incoming signal. Mixing the frequencies results to leaving the IF 455 Khz which is amplified then detected.
In a DCR (Direct Conversion Receiver), no diode is used. a mixer down-verts the frequency to the audio range. So, it converts RF to AF directly by mixing.
Monday, July 23, 2018
RADIO TRANSCEIVERS
July 24, 2018
Well, we discussed the crude arc transmitters used by Marconi. The modern transmitter revolved around the vacuum tube which made oscillators possible. And crystals made it possible to maintain a certain frequency.
The oscillator 's signal was amplified and the radio waves transmitted into the environment.
That is the hardware side. We have to go back on how information is sent using this oscillator.
MAXWELL SAID THAT IF WE CAN PROPAGATE RADIO WAVES WHICH IS A SINE WAVE WHICH CAN BE PICKED UP AND AMPLIFIED BY A RECEIVER, PERHAPS BY MAKING THE STRENGTH OF THE SIGNAL WEAK AND STRONG, WE CAN DETECT THIS AT THE RECEIVER'S END. WEAK AND STRONG OF COURSE REFERS TO AMPLITUDE. THE WORD USED TO DESCRIBE THIS WAS MODULATION.
AMPLITUDE MODULATION WAS BORN. THE MOST POPULAR FOR A LONG TIME COMMERCIAL RADIO WAS AM FOR AMPLITUDE MODULATION. THE TOY WALKIE TALKIE IS AM. PILOTS TALKING TO THE AIRPORT TOWER IS ON AM. FM CAME LATER.
WE WILL FOLLOW THE CHRONOLOGY OF RADIO WAVE TRANSMISSION.
IN AM, THERE IS A CARRIER WAVE WHICH IS ALWAYS ON. THE FREQUENCY SET. IF YOU TURN ON YOUR FAVE AM STATION, SAY 630 KHZ, WHEN NO ONE IS TALKING, YOU CAN HEAR THE HISSING SOUND UNTIL THE RADIO TECHNICIAN SAYS GOODNIGHT AND TURNS THE CARRIER OFF.
WHEN THE ANNOUNCER TALKS, HIS SPEECH WHICH IS ON THE AUDIO RANGE INFLUENCES THE POWER GIVEN TO THE TRANSMITTER AND THE AMPLITUDE IS MOVED ACCORDING LY.
IN THE RECEIVER, THE RADIO WAVE IS PICKED UP, AMPLIFIED, AND CONVERTED TO DC. THE DC CURRENT WILL FLUCTUATE IN ACCORDANCE WITH THE SIGNAL STRENGTH RECEIVED WHICH IS THE MODULATION. THE SPEECH OF THE ANNOUNCER IS THEN HEARD.
CONCLUSIONS
1. AM TRANSMISSION SENDS A CONTINUOUS CARRIER WAVE WHICH COSTS ENERGY
TO SEND. IT IS TRANSMITTED EVEN IF NO ONE IS TALKING.(WASTED ENERGY).
2. AM TRANSMISSION SENDS BOTH THE UPPER BAND, THE POSITIVE SIDE OF THE SINE
WAY AND THE LOWER BAND. SINCE BOTH ARE COMMONLY MODULATED, THERE IS
DUPLICATION.(ANOTHER WASTE).
3. IN THE RECEIVER, ONLY ONE BAND IS DETECTED BECAUSE A DIODE WILL IGNORE
ONE PHASE.. THE OTHER BAND UNNECESSARY.
CONCEPT AND WISH
IF WE CAN SEND ONLY ONE SIDE BAND WHICH HAS THE VOICE ANYWAY AND DO
AWAY WITH THE CARRIER WAVE AND THE OTHER SIDEDBAND, IT WILL TAKE LESS
ENERGY TO TRANSMIT JUST ONE SIDE BAND..
CONVERSELY, THE SAME ENERGY AVAILABLE CAN BE DEDICATED TO ONE
SIDE BAND. THE ACCEPTED RATIO IS 3:1. A 10 W AM TRANSMITTER WILL LOOK
LIKE A 30W TRANSMITTER IF ONLY ONE SIDE BAND IS SENT.
I THINK THE RADIO AMATEURS AFTER THE WAR CONCEPTUALIZED THIS IDEA.
LATER ON, THE FCC IN THE US ALLOWED CB RADIOS TO HAVE SSB AND IT CAN
COVER LONGER DISTANCES.
OF COURSE AMATEURS ALL OVER THE WORLD USED SSB IN THEIR HF
TRANSCEIVERS. AFTER THE WAR, THIS TECHNOLOGY WAS AVAILABLE IN THE
PHILIPPINES AND SSB HF TRANSCEIVER MAKERS CROPPED UP IN MANILA. ONE
OF THEM WAS A COMPANY CALLED "MEDALIST". TAIWANESE TECHNICIANS CAME
TO MANILA TO LEARN HOW TO MAKE TUBE TYPES SSB TRANSCEIVERS WHICH
CAN REACH GREAT DISTANCES.
TODAY , I HAVE TWO OF THESE TUBE TYPE SSB RADIOS AND THEY TRANSIT 100
WATTS.AM NOT OPERATING THEM THO.
HOW IS A SINGLE SIDE BAND SEPARATED AND TRANSMITTED SINGLY. TO
UNDERSTAND IT, WE MUST FIRST UNDERSTAND THE BEHAVIOR OF RADIO
FREQUENCIES WHEN MIXED.
WHEN TWO FREQUENCIES ARE MIXED, THE RESULT IS THE SUM AND
DIFFERENCE OF THOSE FREQUENCIES AND THE ORIGINAL FREQUENCIES
THEMSELVES AVAILABLE AT THE OUTPUT.
TAKE THE CASE OF THE SUPER HETERODYNE AM RADIO. AN ANTENNA PICKS
UP A STATION SAY 630 MHZ. IT IS FED INTO THE BASE OF A TRANSISTOR VIA A
CAP SO THAT THE BASE WILL NOT BE SHORTED TO GROUND.
THE SAME TRANSISTOR IS SET UP AS AN OSCILLATOR WITH A COIL
TRANSFORMER TICKLED BY THE COLLECTOR AND A SECONDARY
FEED BACKING THE SIGNAL TO THE EMITTER OF THE TRANSISTOR. THE
OSCILLATOR IS VARIABLE BY ONE GANG OF A VARICAP. THE TRANSISTOR ACTS
AS A MIXER.
THE OUTPUT FROM THE TRANSISTOR ARE FOUR FREQUENCIES: ONE FROM THE
ANTENNA, ONE FROM THE LOCAL OSCILLATOR AND TWO COMBINATIONS,
THE SUM AND DIFFERENCE OF THE ORIGINAL FREQUENCIES. TO SELECT THE
FREQUENCY WE WANT, TUNED TRANSFORMERS ARE USED CALLED
INTERMEDIATE FREQUENCY TRANSFORMERS, IFT. IN AM RADIOS, THIS IS
AT 455 KHZ.
THE DIFFERENCE IN FREQUENCIES BETWEEN THE RECEIVED SIGNAL AND
THE LOCAL OSCILLATOR MUST BE 455 KHZ. THE LOCAL OSC. IS SET TO BE
455 KHZ HIGHER THAN THE STATION'S FREQUENCY.
THE 45 KHZ SIGNAL IS AMPLIFIED AND THEN A DIODE CONVERTS IT TO DC.
WE CAN HEAR THE INFORMATION.
CLARIFICATION
We say that in AM, the AC is converted to DC and the DC fluctuates with the voice. But
actually even though the amplitude is said to have been modulated, there are frequencies
involved which follows the same rule in frequencies mixing.
Let us say instead of voice, a 1 Khz tone is modulating the transmitter. The envelopes created
are still the carrier frequency, in our example, 630 Khz, the upper band, 630+1 Mhz and the
lower band 630-1 Khz. It is 631 Khz and 629 Khz.
This is where a BALANCED MODULATOR comes in. It cancels the carrier frequency,
leaving only the two side bands. How do we then remove one side band. We use a crystal filter
which will allow only one side band and not the other. The crystal filter is actually like the
intermediate frequency. it could be any frequency.
For the example above, we can use a 631 Khz crystals which will pass only the upper side
band. But we don't have to to use 631 Khz crystals. We can mix the 631 Mhz with another
frequency and get a difference of say 455 Khz..In fact, the tube type SSBs I have both use the
455 Khz filter, altho not crystals but mechanical filters. Where is the 629 Mhz. Well it will be
2 Khz below the 631 Khz, right? so, it is on 453 Mhz in the IF. The 455 Khz filter will reject
it
SO, THERE WE GO, WE NOW HAVE ONLY ONE SIDE BAND AND IT AT
455 KHZ. HOW DO WE GET THE AUDIO OUT, THE 1 KHZ TONE? WE INSERT
TO A SECOND BALANCE MIXER WHERE THE DIFFERENTIAL FREQUENCY
IS 1 KHZ! THAT FREQUENCY SHOULD BE 454 KHZ. THEN WE HEAR THE
1 KHZ TONE!
REMEMBER WE CAN CONVERT INTO ANOTHER FREQUENCY BUT RETAIN
THE MODULATION. ISN'T THAT HOW ITS DONE IN THE REGULAR AM RADIO?
THE STATIONS FREQ. IS MIXED WITH A LOCAL OSC. WITH A FREQ, HIGHER
BY 455 HZ. THE RESULTING FREQ. IS 455 KHZ WHICH IS RECOGNIZED BY
THE SUBSEQUENT TUNED AMPLIFIERS.
Well, we discussed the crude arc transmitters used by Marconi. The modern transmitter revolved around the vacuum tube which made oscillators possible. And crystals made it possible to maintain a certain frequency.
The oscillator 's signal was amplified and the radio waves transmitted into the environment.
That is the hardware side. We have to go back on how information is sent using this oscillator.
MAXWELL SAID THAT IF WE CAN PROPAGATE RADIO WAVES WHICH IS A SINE WAVE WHICH CAN BE PICKED UP AND AMPLIFIED BY A RECEIVER, PERHAPS BY MAKING THE STRENGTH OF THE SIGNAL WEAK AND STRONG, WE CAN DETECT THIS AT THE RECEIVER'S END. WEAK AND STRONG OF COURSE REFERS TO AMPLITUDE. THE WORD USED TO DESCRIBE THIS WAS MODULATION.
AMPLITUDE MODULATION WAS BORN. THE MOST POPULAR FOR A LONG TIME COMMERCIAL RADIO WAS AM FOR AMPLITUDE MODULATION. THE TOY WALKIE TALKIE IS AM. PILOTS TALKING TO THE AIRPORT TOWER IS ON AM. FM CAME LATER.
WE WILL FOLLOW THE CHRONOLOGY OF RADIO WAVE TRANSMISSION.
IN AM, THERE IS A CARRIER WAVE WHICH IS ALWAYS ON. THE FREQUENCY SET. IF YOU TURN ON YOUR FAVE AM STATION, SAY 630 KHZ, WHEN NO ONE IS TALKING, YOU CAN HEAR THE HISSING SOUND UNTIL THE RADIO TECHNICIAN SAYS GOODNIGHT AND TURNS THE CARRIER OFF.
WHEN THE ANNOUNCER TALKS, HIS SPEECH WHICH IS ON THE AUDIO RANGE INFLUENCES THE POWER GIVEN TO THE TRANSMITTER AND THE AMPLITUDE IS MOVED ACCORDING LY.
IN THE RECEIVER, THE RADIO WAVE IS PICKED UP, AMPLIFIED, AND CONVERTED TO DC. THE DC CURRENT WILL FLUCTUATE IN ACCORDANCE WITH THE SIGNAL STRENGTH RECEIVED WHICH IS THE MODULATION. THE SPEECH OF THE ANNOUNCER IS THEN HEARD.
CONCLUSIONS
1. AM TRANSMISSION SENDS A CONTINUOUS CARRIER WAVE WHICH COSTS ENERGY
TO SEND. IT IS TRANSMITTED EVEN IF NO ONE IS TALKING.(WASTED ENERGY).
2. AM TRANSMISSION SENDS BOTH THE UPPER BAND, THE POSITIVE SIDE OF THE SINE
WAY AND THE LOWER BAND. SINCE BOTH ARE COMMONLY MODULATED, THERE IS
DUPLICATION.(ANOTHER WASTE).
3. IN THE RECEIVER, ONLY ONE BAND IS DETECTED BECAUSE A DIODE WILL IGNORE
ONE PHASE.. THE OTHER BAND UNNECESSARY.
CONCEPT AND WISH
IF WE CAN SEND ONLY ONE SIDE BAND WHICH HAS THE VOICE ANYWAY AND DO
AWAY WITH THE CARRIER WAVE AND THE OTHER SIDEDBAND, IT WILL TAKE LESS
ENERGY TO TRANSMIT JUST ONE SIDE BAND..
CONVERSELY, THE SAME ENERGY AVAILABLE CAN BE DEDICATED TO ONE
SIDE BAND. THE ACCEPTED RATIO IS 3:1. A 10 W AM TRANSMITTER WILL LOOK
LIKE A 30W TRANSMITTER IF ONLY ONE SIDE BAND IS SENT.
I THINK THE RADIO AMATEURS AFTER THE WAR CONCEPTUALIZED THIS IDEA.
LATER ON, THE FCC IN THE US ALLOWED CB RADIOS TO HAVE SSB AND IT CAN
COVER LONGER DISTANCES.
OF COURSE AMATEURS ALL OVER THE WORLD USED SSB IN THEIR HF
TRANSCEIVERS. AFTER THE WAR, THIS TECHNOLOGY WAS AVAILABLE IN THE
PHILIPPINES AND SSB HF TRANSCEIVER MAKERS CROPPED UP IN MANILA. ONE
OF THEM WAS A COMPANY CALLED "MEDALIST". TAIWANESE TECHNICIANS CAME
TO MANILA TO LEARN HOW TO MAKE TUBE TYPES SSB TRANSCEIVERS WHICH
CAN REACH GREAT DISTANCES.
TODAY , I HAVE TWO OF THESE TUBE TYPE SSB RADIOS AND THEY TRANSIT 100
WATTS.AM NOT OPERATING THEM THO.
HOW IS A SINGLE SIDE BAND SEPARATED AND TRANSMITTED SINGLY. TO
UNDERSTAND IT, WE MUST FIRST UNDERSTAND THE BEHAVIOR OF RADIO
FREQUENCIES WHEN MIXED.
WHEN TWO FREQUENCIES ARE MIXED, THE RESULT IS THE SUM AND
DIFFERENCE OF THOSE FREQUENCIES AND THE ORIGINAL FREQUENCIES
THEMSELVES AVAILABLE AT THE OUTPUT.
TAKE THE CASE OF THE SUPER HETERODYNE AM RADIO. AN ANTENNA PICKS
UP A STATION SAY 630 MHZ. IT IS FED INTO THE BASE OF A TRANSISTOR VIA A
CAP SO THAT THE BASE WILL NOT BE SHORTED TO GROUND.
THE SAME TRANSISTOR IS SET UP AS AN OSCILLATOR WITH A COIL
TRANSFORMER TICKLED BY THE COLLECTOR AND A SECONDARY
FEED BACKING THE SIGNAL TO THE EMITTER OF THE TRANSISTOR. THE
OSCILLATOR IS VARIABLE BY ONE GANG OF A VARICAP. THE TRANSISTOR ACTS
AS A MIXER.
THE OUTPUT FROM THE TRANSISTOR ARE FOUR FREQUENCIES: ONE FROM THE
ANTENNA, ONE FROM THE LOCAL OSCILLATOR AND TWO COMBINATIONS,
THE SUM AND DIFFERENCE OF THE ORIGINAL FREQUENCIES. TO SELECT THE
FREQUENCY WE WANT, TUNED TRANSFORMERS ARE USED CALLED
INTERMEDIATE FREQUENCY TRANSFORMERS, IFT. IN AM RADIOS, THIS IS
AT 455 KHZ.
THE DIFFERENCE IN FREQUENCIES BETWEEN THE RECEIVED SIGNAL AND
THE LOCAL OSCILLATOR MUST BE 455 KHZ. THE LOCAL OSC. IS SET TO BE
455 KHZ HIGHER THAN THE STATION'S FREQUENCY.
THE 45 KHZ SIGNAL IS AMPLIFIED AND THEN A DIODE CONVERTS IT TO DC.
WE CAN HEAR THE INFORMATION.
CLARIFICATION
We say that in AM, the AC is converted to DC and the DC fluctuates with the voice. But
actually even though the amplitude is said to have been modulated, there are frequencies
involved which follows the same rule in frequencies mixing.
Let us say instead of voice, a 1 Khz tone is modulating the transmitter. The envelopes created
are still the carrier frequency, in our example, 630 Khz, the upper band, 630+1 Mhz and the
lower band 630-1 Khz. It is 631 Khz and 629 Khz.
This is where a BALANCED MODULATOR comes in. It cancels the carrier frequency,
leaving only the two side bands. How do we then remove one side band. We use a crystal filter
which will allow only one side band and not the other. The crystal filter is actually like the
intermediate frequency. it could be any frequency.
For the example above, we can use a 631 Khz crystals which will pass only the upper side
band. But we don't have to to use 631 Khz crystals. We can mix the 631 Mhz with another
frequency and get a difference of say 455 Khz..In fact, the tube type SSBs I have both use the
455 Khz filter, altho not crystals but mechanical filters. Where is the 629 Mhz. Well it will be
2 Khz below the 631 Khz, right? so, it is on 453 Mhz in the IF. The 455 Khz filter will reject
it
SO, THERE WE GO, WE NOW HAVE ONLY ONE SIDE BAND AND IT AT
455 KHZ. HOW DO WE GET THE AUDIO OUT, THE 1 KHZ TONE? WE INSERT
TO A SECOND BALANCE MIXER WHERE THE DIFFERENTIAL FREQUENCY
IS 1 KHZ! THAT FREQUENCY SHOULD BE 454 KHZ. THEN WE HEAR THE
1 KHZ TONE!
REMEMBER WE CAN CONVERT INTO ANOTHER FREQUENCY BUT RETAIN
THE MODULATION. ISN'T THAT HOW ITS DONE IN THE REGULAR AM RADIO?
THE STATIONS FREQ. IS MIXED WITH A LOCAL OSC. WITH A FREQ, HIGHER
BY 455 HZ. THE RESULTING FREQ. IS 455 KHZ WHICH IS RECOGNIZED BY
THE SUBSEQUENT TUNED AMPLIFIERS.
VACUUM TUBES, THE HEART OF MODERN RADIO
JULY 24, 2018
I started this new topic beginning with the vacuum tube. Edison started it all. He just wanted a bulb and somewhere it is claimed that he himself stumbled upon the diode property in his tube but ignored it. a British bough his tubes and experimented and got the credit. John Fleming.
But it did not stop with Fleming. Others played around with Edison's bulb. We can say that the real inventor of a vacuum device was Edison. Fleming made it into a DIODE. Back to America in 1906 , Lee De Forrest invented the TRIODE.
Vacuum triode
Electrodes of
vacuum triode
The vacuum-tube feedback oscillator was invented around 1912, when it
was discovered that feedback ("regeneration") in the recently invented audion vacuum tube
could produce oscillations. At least six researchers independently
made this discovery, although not all of them can be said to have a role
in the invention of the oscillator.[22][23] In the summer of 1912, Edwin Armstrong observed oscillations in audion radio receiver circuits[24] and went on to use positive feedback in his invention of the regenerative receiver.[25][26] Austrian Alexander Meissner independently discovered positive feedback and invented oscillators in March 1913.[24][27] Irving Langmuir at General Electric observed feedback in 1913.[27] Fritz Lowenstein may have preceded the others with a crude oscillator in late 1911.[28] In Britain, H. J. Round patented amplifying and oscillating circuits in 1913.[24] In August 1912, Lee De Forest,
the inventor of the audion, had also observed oscillations in his
amplifiers, but he didn't understand its significance and tried to
eliminate it[29][30] until he read Armstrong's patents in 1914,[31] which he promptly challenged.[32] Armstrong and De Forest fought a protracted legal battle over the rights to the "regenerative" oscillator circuit[32][33] which has been called "the most complicated patent litigation in the history of radio".[34]
De Forest ultimately won before the Supreme Court in 1934 on technical
grounds, but most sources regard Armstrong's claim as the stronger one.[30][32]
This was the beginning of radio wave creation in a vacuum tube and propagation.
GOD GAVE US EVERYTHING
Ok by 1912, oscillators were made out of vacuum tubes. but the problem was how to keep the frequency stable. Comesd the quartz crystal.
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a precise frequency.[1][2][3] This frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is the quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators,[1] but other piezoelectric materials including polycrystalline ceramics are used in similar circuits.
A crystal oscillator, particularly one made of quartz crystal, works by being distorted by an electric field when voltage is applied to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity. When the field is removed, the quartz - which oscillates in a precise frequency - generates an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like an RLC circuit.
Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.
I started this new topic beginning with the vacuum tube. Edison started it all. He just wanted a bulb and somewhere it is claimed that he himself stumbled upon the diode property in his tube but ignored it. a British bough his tubes and experimented and got the credit. John Fleming.
But it did not stop with Fleming. Others played around with Edison's bulb. We can say that the real inventor of a vacuum device was Edison. Fleming made it into a DIODE. Back to America in 1906 , Lee De Forrest invented the TRIODE.
Vacuum triode
The
basic vacuum tube (vacuum
diode) is used to convert the alternating current into
direct current. However, they cannot amplify the electric
signal. In other words, they cannot amplify the voltage
or power. To amplify the electrical signal, an extra
electrode is required. When the extra electrode is placed
between the cathode and anode, the resulting electronic device
is called vacuum triode.
The name itself
indicates that, it has three electrodes: cathode, anode, and
control grid. American electrical engineer Lee De Forest
invented the first electronic amplifying device (vacuum
triode) in 1906 by adding an extra electrode (control grid)
between the cathode and anode. Vacuum triode is a 3-electrode
device that amplifies the electrical signal.
Electrodes of
vacuum triode
Vacuum triode
consists of three electrodes: anode, cathode and control grid.
The anode, cathode and control grid are enclosed in an empty
glass envelope. The cathode is surrounded by a control grid,
which is in turn surrounded by anode. The construction of
vacuum triode is similar to vacuum diode. However, vacuum
triode contains an extra electrode (control grid).
Cathode emits the free
electrons when it is heated. Hence, cathode is also
called as emitter. The process by which cathode emits the free
electrons when it is heated is called thermionic
emission. Anode collects the free electrons that are
emitted by the cathode. Hence, anode or plate is also called
as collector.
In between the
anode and cathode, control grid is present. Control grid is
placed more nearer to the cathode than anode to increase the
electric current efficiently. Control grid will control the
flow of electrons between the cathode and anode. Hence,
control grid is also called as electron controller or electric
current controller.
Control grid is
made of network of wires that controls the electrons flow
between the cathode and anode. The space between the network
of wires in the grid is very large. Hence, the free electrons
move easily from cathode to anode through the opening of the
control grid. Free electrons that are moving from cathode to
anode will carry the electric current.
In 1906, the US (Admiral Dewey) just dislodged the Spaniards from Asia. Dewey with modern steam vessels sank Admiral Montojo's navy of sail ships to the bottom of Manila Bay. The world was young and yet technology began to appear.
The TRIODE made all the difference cuz it could amplify weak signals.
This was the beginning of radio wave creation in a vacuum tube and propagation.
GOD GAVE US EVERYTHING
Ok by 1912, oscillators were made out of vacuum tubes. but the problem was how to keep the frequency stable. Comesd the quartz crystal.
Crystal oscillator
Jump to navigation Jump to search
A miniature 16 MHz quartz crystal enclosed in a hermetically sealed HC-49/S package, used as the resonator in a crystal oscillator.
| |
| Type | Electromechanical |
|---|---|
| Working principle | Piezoelectricity, Resonance |
| Invented | Alexander M. Nicholson, Walter Guyton Cady |
| First production | 1918 |
| Electronic symbol | |
 | |
A crystal oscillator, particularly one made of quartz crystal, works by being distorted by an electric field when voltage is applied to an electrode near or on the crystal. This property is known as electrostriction or inverse piezoelectricity. When the field is removed, the quartz - which oscillates in a precise frequency - generates an electric field as it returns to its previous shape, and this can generate a voltage. The result is that a quartz crystal behaves like an RLC circuit.
Quartz crystals are manufactured for frequencies from a few tens of kilohertz to hundreds of megahertz. More than two billion crystals are manufactured annually. Most are used for consumer devices such as wristwatches, clocks, radios, computers, and cellphones. Quartz crystals are also found inside test and measurement equipment, such as counters, signal generators, and oscilloscopes.
July 24, 2018
Hi Friends,
One of the early guys who spoke of radio waves was Faraday, in Europe. Then came out an American, Maxwell, who wrote on it. They all spoke and wrote about the SINE WAVE, as a wave traveling in space. It is AC in characteristic as how waves are, it shifts polarities. We all know that a since wave has a positive phase and a negative phase. It was Maxwell who wrote a paper that we can send information using this radio wave. The theory came way ahead of being able to produce sine waves. We also know that Marconi, Italian, registered his patent in England on how to produce sine waves. There no vacuum tubes yet, no semiconductors. Marconi used SPARK GAPS. Yes, he was creating sparks just like the spark in a spark plug of a motorcycle. Did you hear your radio pick up a passing motorcycle? That was how Marconi did it and sent the first trans Atlantic signal to the U.S. Basically, it must have been like the ignition coil in a car or motorcycle. It was all battery and coils. But the sparks he produced was very very broadband. The FCC would have been after him. Fortunately there was no FCC yet! and nobody minded because people did not have sophisticated receivers to hear his sparks! But Marconi had one in the east coast of the U.S., Newfoundland I think. His people heard the spark. How did he built in information. Well, he adopted the Morse Code. He must have found a way to create two distinct sounds of sparks.
To detect the signal, galena crystals became popular. It became know n as the detector. Then Edison of Ohio, USA came into the picture. He was not concerned about radio. He was concerned about lighting up the streets of Ohio and the entire USA. During his time, dynamos were already known. Faraday and Volta used batteries which DC. Later on, it was discovered that a magnet running around coils of wires produced electricity. It was AC but since the orientation at that time was DC, a commutator was installed in the dynamos to collect all the + and the - separately. So, it was DC dynamos everywhere in the U.S. Edison was a DC believer. All over the place DC current lighted up streets. How? with ARC LAMPS. Two carbon elements continually burning which needed constant adjustments. Edison invented the vacuum light bulb. Since there was no oxygen inside the bulb, the element did not burn.
Experimenters picked up on Edison's bulb and one of them was Fleming in England. No not Ian Fleming who produced James Bond. they moved on to invent the Fleming valve. Here is a copy-paste from Wikipedia.
The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by Englishman John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite direction. The thermionic diode was later widely used as a rectifier — a device which converts alternating current (AC) into direct current (DC) — in the power supplies of a wide range of electronic devices, until beginning to be replaced by the selenium rectifier in the early 1930s and almost completely replaced by the semiconductor diode in the 1960s. The Fleming valve was the forerunner of all vacuum tubes, which dominated electronics for 50 years. The IEEE has described it as "one of the most important developments in the history of electronics",[1] and it is on the List of IEEE Milestones for electrical engineering.
Open this link about Faraday:
https://www.bbvaopenmind.com/en/science/.../faraday-electromagnetic-theory-light/
Please copy paste to open.
.This was Faraday in 1856. He spoke of radio waves in 1846.
The idea that light is an electromagnetic wave had occurred to Faraday while Maxwell was still a schoolboy, but Maxwell was the first person to possess a complete set of equations describing the dynamical behaviour of electric and magnetic fields. Believing that Faraday was correct, Maxwell set out to show that his equations have wave-like solutions that propagate through empty space at the speed of light.
Electric and magnetic fields are produced by charges and currents, but these fields also extend into surrounding regions of empty space. For example, charges and currents in the Sun produce electromagnetic fields which travel across almost empty space before reaching sunbathers on a beach on Earth. The detailed relationship between the fields and their sources will not be discussed here. Instead, we take the existence of time-varying electric and magnetic fields for granted, and concentrate on their propagation through space. In empty space, the charge and current densities are equal to zero, so Maxwell's equations become
Our aim is to show that these equations have wave-like solutions
which describe oscillating electric and magnetic fields that propagate
through space. These wave-like solutions are called electromagnetic waves.
This link summarizes it all. Hertz ( German) demonstrated the arc transmiter at the end of the 10th century and Marconi made a practical transmitter in the early 20th century.
https://en.wikipedia.org/wiki/Transmitter
Hi Friends,
One of the early guys who spoke of radio waves was Faraday, in Europe. Then came out an American, Maxwell, who wrote on it. They all spoke and wrote about the SINE WAVE, as a wave traveling in space. It is AC in characteristic as how waves are, it shifts polarities. We all know that a since wave has a positive phase and a negative phase. It was Maxwell who wrote a paper that we can send information using this radio wave. The theory came way ahead of being able to produce sine waves. We also know that Marconi, Italian, registered his patent in England on how to produce sine waves. There no vacuum tubes yet, no semiconductors. Marconi used SPARK GAPS. Yes, he was creating sparks just like the spark in a spark plug of a motorcycle. Did you hear your radio pick up a passing motorcycle? That was how Marconi did it and sent the first trans Atlantic signal to the U.S. Basically, it must have been like the ignition coil in a car or motorcycle. It was all battery and coils. But the sparks he produced was very very broadband. The FCC would have been after him. Fortunately there was no FCC yet! and nobody minded because people did not have sophisticated receivers to hear his sparks! But Marconi had one in the east coast of the U.S., Newfoundland I think. His people heard the spark. How did he built in information. Well, he adopted the Morse Code. He must have found a way to create two distinct sounds of sparks.
To detect the signal, galena crystals became popular. It became know n as the detector. Then Edison of Ohio, USA came into the picture. He was not concerned about radio. He was concerned about lighting up the streets of Ohio and the entire USA. During his time, dynamos were already known. Faraday and Volta used batteries which DC. Later on, it was discovered that a magnet running around coils of wires produced electricity. It was AC but since the orientation at that time was DC, a commutator was installed in the dynamos to collect all the + and the - separately. So, it was DC dynamos everywhere in the U.S. Edison was a DC believer. All over the place DC current lighted up streets. How? with ARC LAMPS. Two carbon elements continually burning which needed constant adjustments. Edison invented the vacuum light bulb. Since there was no oxygen inside the bulb, the element did not burn.
Experimenters picked up on Edison's bulb and one of them was Fleming in England. No not Ian Fleming who produced James Bond. they moved on to invent the Fleming valve. Here is a copy-paste from Wikipedia.
The Fleming valve, also called the Fleming oscillation valve, was a thermionic valve or vacuum tube invented in 1904 by Englishman John Ambrose Fleming as a detector for early radio receivers used in electromagnetic wireless telegraphy. It was the first practical vacuum tube and the first thermionic diode, a vacuum tube whose purpose is to conduct current in one direction and block current flowing in the opposite direction. The thermionic diode was later widely used as a rectifier — a device which converts alternating current (AC) into direct current (DC) — in the power supplies of a wide range of electronic devices, until beginning to be replaced by the selenium rectifier in the early 1930s and almost completely replaced by the semiconductor diode in the 1960s. The Fleming valve was the forerunner of all vacuum tubes, which dominated electronics for 50 years. The IEEE has described it as "one of the most important developments in the history of electronics",[1] and it is on the List of IEEE Milestones for electrical engineering.
Open this link about Faraday:
https://www.bbvaopenmind.com/en/science/.../faraday-electromagnetic-theory-light/
Please copy paste to open.
.This was Faraday in 1856. He spoke of radio waves in 1846.
Electromagnetic waves
This section gives a brief introduction to light and electromagnetic waves.The idea that light is an electromagnetic wave had occurred to Faraday while Maxwell was still a schoolboy, but Maxwell was the first person to possess a complete set of equations describing the dynamical behaviour of electric and magnetic fields. Believing that Faraday was correct, Maxwell set out to show that his equations have wave-like solutions that propagate through empty space at the speed of light.
Electric and magnetic fields are produced by charges and currents, but these fields also extend into surrounding regions of empty space. For example, charges and currents in the Sun produce electromagnetic fields which travel across almost empty space before reaching sunbathers on a beach on Earth. The detailed relationship between the fields and their sources will not be discussed here. Instead, we take the existence of time-varying electric and magnetic fields for granted, and concentrate on their propagation through space. In empty space, the charge and current densities are equal to zero, so Maxwell's equations become
This link summarizes it all. Hertz ( German) demonstrated the arc transmiter at the end of the 10th century and Marconi made a practical transmitter in the early 20th century.
https://en.wikipedia.org/wiki/Transmitter
Friday, July 20, 2018
Today is July 20, 2018. I will update when I can. I just opened the FB account of Ateneo de Zamboanga, ECE students. I sent a message and mentioned this blog and for anyone who opened this blog, welcome.
A bit of myself;
Born in 1950, Burleigh School Grades 1-4, then Ateneo de Zamboanga. The first Jesuit encounter was Fr. Eusebio Salvador who happened to have married my parents in 1948. Also Fr. Simeon Reyes who was in GS. Graduated Salutatorian with two medals: Gold in RELIGION and Silver in ARITHMETIC.
Entered HS in 1963. Favorite Jesuits Fr. Asterio Katigbak and Fr. Charles Duffy. Frequented Fr. Loredo's office, student counselor. I saw a booklet in his shelf "How to make a Foxhole Radio". I was hooked. I scrimped and saved to buy the headset for P14 from City Radio. Toilet paper core, magnetic wires. Pencil carbon on razor blade as diode. IT WORKED. My uncle beside our house had junks and I found a variable condenser. Then I went back to City Radio and bought an OC44 Phillips transistor and was able to amplifiy the audio to drive a speaker. My room on the 2nd floor had wires strung in the window.
The the Jesuits sent me to the USA in 1967 as the AFS scholar.. I went to a HS in Lee's Summit , Missouri. I enrolled in BASIC ELECTRONICS. Came home with a pair of Jenssen speakers which I blew up with my homebrew tube amplifiers. I was sent to ADMU in 1968 but weekends were in Raon.
Fast forward 1978, I fell in love with RC model airplanes. I was in training in HK for 6 months and bought any books in electronics and RC even if they were in Cantonese. Brought these books home which apparently were original from the UK and translated. Ordered RC radio kits from the US and built, built, and built until I could build RC transmitters and receivers from scratch parts locally available. I built airplanes and boats but electronics was the overriding passion. Came the electrics. I built ESC (motor speed control) and rewound brush less motors. Became familiar with newer batteries, Li Po, Li Ion, etc...and chargers.
At the same time, I bought a 2 meter Yaesu transceiver and was on the air. Subsequently acquired Icoms and other brands 2 meter radios. Bought several CB radios in the US. My fav destination there was Radio Shack.Still have several radios.
Built PODs, Igniters for cars, AC controller for cars, heater timers for diesel engines and others.
Most recent interests were in radio receivers, regeneratives, TRFs, superhets, double conversions, etc..and SW radios, AM and SSB.
Just ordered chips for a 40 meter transceiver which can reach worldwide with about 100 watts of power.
Served as project consultants to ECE and ME students here in Manila. Built their projects (robots and featured in ABS CBN. Robots, controlling the V in a hydro-generator(La Salle). Latest is sonar communications under water using tones and digital, using FSK.
It will be fun to meet with you guys and gals. Feel free to contact me: 0933 275 5010 or bongdeleonko@yahoo.com My FB account is Bong Ko.
A bit of myself;
Born in 1950, Burleigh School Grades 1-4, then Ateneo de Zamboanga. The first Jesuit encounter was Fr. Eusebio Salvador who happened to have married my parents in 1948. Also Fr. Simeon Reyes who was in GS. Graduated Salutatorian with two medals: Gold in RELIGION and Silver in ARITHMETIC.
Entered HS in 1963. Favorite Jesuits Fr. Asterio Katigbak and Fr. Charles Duffy. Frequented Fr. Loredo's office, student counselor. I saw a booklet in his shelf "How to make a Foxhole Radio". I was hooked. I scrimped and saved to buy the headset for P14 from City Radio. Toilet paper core, magnetic wires. Pencil carbon on razor blade as diode. IT WORKED. My uncle beside our house had junks and I found a variable condenser. Then I went back to City Radio and bought an OC44 Phillips transistor and was able to amplifiy the audio to drive a speaker. My room on the 2nd floor had wires strung in the window.
The the Jesuits sent me to the USA in 1967 as the AFS scholar.. I went to a HS in Lee's Summit , Missouri. I enrolled in BASIC ELECTRONICS. Came home with a pair of Jenssen speakers which I blew up with my homebrew tube amplifiers. I was sent to ADMU in 1968 but weekends were in Raon.
Fast forward 1978, I fell in love with RC model airplanes. I was in training in HK for 6 months and bought any books in electronics and RC even if they were in Cantonese. Brought these books home which apparently were original from the UK and translated. Ordered RC radio kits from the US and built, built, and built until I could build RC transmitters and receivers from scratch parts locally available. I built airplanes and boats but electronics was the overriding passion. Came the electrics. I built ESC (motor speed control) and rewound brush less motors. Became familiar with newer batteries, Li Po, Li Ion, etc...and chargers.
At the same time, I bought a 2 meter Yaesu transceiver and was on the air. Subsequently acquired Icoms and other brands 2 meter radios. Bought several CB radios in the US. My fav destination there was Radio Shack.Still have several radios.
Built PODs, Igniters for cars, AC controller for cars, heater timers for diesel engines and others.
Most recent interests were in radio receivers, regeneratives, TRFs, superhets, double conversions, etc..and SW radios, AM and SSB.
Just ordered chips for a 40 meter transceiver which can reach worldwide with about 100 watts of power.
Served as project consultants to ECE and ME students here in Manila. Built their projects (robots and featured in ABS CBN. Robots, controlling the V in a hydro-generator(La Salle). Latest is sonar communications under water using tones and digital, using FSK.
It will be fun to meet with you guys and gals. Feel free to contact me: 0933 275 5010 or bongdeleonko@yahoo.com My FB account is Bong Ko.
Wednesday, July 18, 2018
INTRO-July 18, 2018
This blog is opened particularly for ECE students. This will focus on communications, analog, the fundamentals. It is the middle word in their course: ECE. Many ECE students I meet are focused on literature and theories but could not even build a walkie talkie.
Many fear chokes and coils (inductors). We shall endeavor to DEMYSTIFY coils and chokes.
Making an audio amplifier is easy. Even if it is very distorted, it will work and pass. But not in RF works.
So, guys and gals, come on. join me and comment. It will be a free-wheeling discussions.
I would like to tell you something. Building an SSB transceiver today is much easier and you can build it. Build a pair among friends and you don't have to speak inter-island. Just kilometers away between friends.
But be prepared, you will be able to listen to the amateurs from around the world!
PLEASE POST YOU INTERESTS.......WELCOME.
BRAVOKILO 09332755010
Many fear chokes and coils (inductors). We shall endeavor to DEMYSTIFY coils and chokes.
Making an audio amplifier is easy. Even if it is very distorted, it will work and pass. But not in RF works.
So, guys and gals, come on. join me and comment. It will be a free-wheeling discussions.
I would like to tell you something. Building an SSB transceiver today is much easier and you can build it. Build a pair among friends and you don't have to speak inter-island. Just kilometers away between friends.
But be prepared, you will be able to listen to the amateurs from around the world!
PLEASE POST YOU INTERESTS.......WELCOME.
BRAVOKILO 09332755010
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