What liquid can be used for solar heaters, Τι υγρό χρησιμοποιούμε στους ηλιακούς θερμοσίφωνες

Με δικη σας ευθύνη.


Διαβάζοντας το datasheet της BASF για το Glythermin P44
http://glythermin.ru/d/599572/d/ti-glythermin-p44.pdf

 
έχω την εντύπωση ότι το Glythermin 75 είναι Glythermin P44 25% κατά όγκο δηλαδή 25 Glythermin P44 και 75 νερό. Ψάξτε το μονοι σας και δοκιμάστε με δικη σας ευθύνη.


Έτσι τελικά αγόρασα 1 λίτρο Elton's Iliothermine  που είναι και αυτό βασισμένο στην προπυλενογλυκόλη  (propylene glycol) και πρόσθεσα 3 λίτρα απιονισμένο AB 365 νερό. Το Elton's το βρήκα στο μαγαζί με τα φίλτρα νερού στο metro Νέου Κόσμου με 10 euro.


Try at your own risk:


By reading  the datasheet of  BASF for Glythermin P44
http://glythermin.ru/d/599572/d/ti-glythermin-p44.pdf


I get the impression that the -10oC Glythermin 75 used in Greece is  Glythermin P44 25% per volume i.e.  25 parts Glythermin P44 and  75 parts water?.


I eneded up using 1 liter of  Elton's Iliothermine  which is also based in propylene glycol and added 3 liters of distilled water..

Pleiades 1:10 microphone input transformer

Turns ratio approx 35 to 350.

Proximity compensation due to 47mH primary inductance.


Secondary inductance 5.1H.


Fully balanced and symmetric input and output coil.


Wound on Magnetec 060 nanocrystalline toroid core.


Secondary wire diameter 0.1mm.


To be used with an early beige MD421 feeding 2 Pleiades stages of battery powered EF183 electron tubes.

Microphone Systematic Error

The bass reduction during the first few minutes was apparently due to the MD-421ii used in the experiments. It sounded great even with no proximity compensating filter. Following entries attributing cause to warming up tubes etc should be edited.

Can a JFET be made to behave like an electron tube?

Could it be that adding a diode + resistor to a JFET across gate make it have automatic gain control for many Megohms Rg or simulating electron tube instant clipping behavior with few MOhms Rg?


The rectificating grid action of the electron tube at large signals increases negative bias, therefore decreasing current, therefore Gm, therefore gain. Vary Gm tubes with deliberate uneven grid must be doing the job even better.


This was first shown to me when I disconnected the capsule from a U47 and applied a signal from a sine generator with 10Db steps. When a large signal was suddenly reduced by 10db gain was increasing by a time constant (coming back to its normal value after automatic gain reduction!), output of VF14 electron tube was an undistorted sinewave all the time.

How to reduce excessive bass and pop filter when your Shure SM-58 is used at a very close distance

How it's done:


Some turns of insulated wire are wound on a toroidal ferrite or nanoperm core. The 2 ends of the inductor are soldered in parallel with the SM-58 voice coil. The core in this example must have been a Philips ferrite wound in around 2008? with 24 turns of wire wrap wire.


How it works:


If one speaks closely to a directional microphone bass increase takes place due to the proximity effect, which is an effect in some way analogous to what causes a tide (difference of gravity from the sun and moon on top and bottom of the earth, the moon is more effective as the difference between top and bottom is greater because it is nearer to us).. [1],[2].


An inductor has an impedance which drops with lowering frequency. At 0 frequency all you are left with is the resistance of the wire. It therefore short circuits low (bass) frequencies.


Inductors (coils) in electrical syatems are analogous to mass in mechanical system and therefore obey the analog of Newton's 2nd low. It says the more slowly you accelerate a mass the easier it is. Try moving back and forth a door at low and then high frequency. In electrical systems current is velocity and voltage is force. An inductor tries to keep current through it constant just as a mass tries to keep speed constant. The slower we move back an forth electrons in an inductor the easier it is, so bass frequencies are short circuited, the easy current makes a large voltage drop in the voice coil resistance. Similar to the rotating speed of a juice extractor dropping when you extract the juice of a fruit. This is conservation of energy and this energy converted to heat is what also acts as a brake to the membrane moving at low frequencies reducing pop and air blasts when the inductor is connected.


More wire turns more bass, or alternatively less turns more treble. Amazing clear treble.


Inspiration for the Pleiades filters came from  the Director of Acoustical and Electromechanical of RCA H.F.Olson in his article: H.F. Olson, Ribbon Velocity Microphones, JAES, 1970 June, Vol 18.
An inductor is connected to the secondary of a ribbon microphone transformer


On this example the inductor is connected before the in house transformer of the SM58, right to the voice coil where the impedance is very low. This makes the construction very easy as very few turns are needed. The primary of the step up transformer is left connected to the voice coil as usual the step up the voltage and therefore impedance to 300 ohms.


Ref:

Hewitt, Conceptual Physics

Hadden, High Quality Sound Reproduction, BBC

 H.F. Olson, Ribbon Velocity Microphones

Pleiades Electra JFET Headphone Amplifier No Components

This is a source follower and the headphone coil (one for each ear channel) acts as the source resistor itself.





Some idea as on electron tube Pleiades Electra 1 and 2 where the headphone coil is the cathode resistor or the plate load resistor itself.


This is a brilliant idea that comes from the book Audio Amplifiers, Editor J.R.Davies, Data Publications, page 41, 2 - Transistor miniature AF amplifier. The AD140 power Germanium transistor has as load resistor the 15 ohms speaker itself. Class A, as electrons flow all the time, bias from collector to base, as simple as life can get, and amazing sound. The Idea also comes from another book by "uncle" Clive Sinclair, Transistor Audio Amplifier Manual. Hi impedance earpieces are used instead of collector load resistors, life is so beautiful.

Pleiades 12V battery powered 12AU7 microphone pre preamplifier or DI with positive bias resistor from plate (anode) to grid to free electrons

This is a mod of a pre amplifier made in around 2000 using an ECC86 which did not work quite well. Many years later it was replaced with 12AU7 at 12V and then after some time  the other end of the 10Mohms grid resistor was connected to Anode where it started to sing.







 Inside view showing 10MOhms from plate to grid. ECC82; sounds great but EF183 is possibly more suitable for low voltage positive grid bias work.

Pleiades K117 JFET battery pre preamplifier 2nd prototype

This is using a FREED input transformer of about 1:60 ! turns ratio and primary inductance of 40mH.


Great for compensating bass proximity effect, amazing sound using an MD-421 foe intimate vocals.


Since this is a source follower of low impedance it can be connected to the input of  a V72.

Pleades K117 JFET microphone pre preamplifier schematic

Thanks to Panayiotis Diamantopoulos who gave me the transformerless schematic.

The art of Music, Electronics and Psychoacoustics

Sound or music comes to our ears by air molecules striking our ear membrane.


When one hits a drum, the drum  membrane vibrates, sets to motion nearby air molecules, which by collision set to motion nearby air molecules until those near to our ear vibrate too.


This transfer of energy is called a wave. It is interesting that the energy flows not the molecules. Like sea waves, water is not transported it is the energy that does.


It is also interesting to note that even in complete silence molecules are random vibrating. The energy is ultimately coming as everything in our planet from coalitions of photos from the sun. It is called thermal motion and depends on temperature. When temperature of water for example is high water molecules vibrate so quickly that they can escape into air, the water boils.


We cannot hear thermal motion of air molecules (silence), because the sensitivity of our ear - brain mechanism is set just on this threshold.  Otherwise life would be difficult hearing a meaningless hissing noise all the time.


Information occurs when something unexpected happens. When a someone sings a note or speaks the air molecules have an extra much larger superimposed vibration.


The simplest tone containing just one frequency is from a tuning fork that last infinite time.


Frequency in the number of complete cycles of a vibration occurring in 1 second (Hertz, Hz). A tuning fork vibrating 440 times per second has a frequency of 440.


It is the note A4, (la 4), the highest la that a man can sing.


An octave is a similar sensation but on higher or lower pitch. It is a close to a multiple of 2 but not exact. So the highest woman la would be somewhat higher than 880Hz. The confusion arouse because in electronic engineering it was found convenient to define an octave as an exact multiple if frequency.


Pitch and frequency are not the same, the first is the psychological impression the other is the objrctive measurement. Pitch obviously increases as frequency increases but also depends on intensity. For example if you listen to a YouTube clip containing a tone of 440Hz you will find that pitch drops appreciably as you increase the volume.


Electronic signals have many common with acoustic signals, the main difference is that instead of molecules we have electrons vibrating.


Electrons are so small that we cannot see, they have negative charge and have the peculiar property that when an electron in universe vibrates an electromagnetic field emmited makes another elceron in the universe vibrate similarly.


For example electrons in the sun make electrons in objects and in our eyes vibrate. Therefore we can witness and see beauty.
.

The waves that make these happen are called electromagnetic and again it is not electrons that move but the energy that flows, furthermore they can travel through empty space.


Electronics is the part of art science and engineering that deals with the control of the movement of electrons.


Sound carrying air molecules striking the membrane of a microphone set in turn corresponding vibrations in the wire coil attached to it. So a microphone converts the vibration  of molecules to similar vibration of electrons.


Vibrating electrons in a metal wire set into vibration the ones nearby and so on up to the other end. The wave is traveling and not the electrons.  The  electromagnetic wave is traveling at the speed light in the material the conductor is made of.


The tiny movement of electrons can be made larger. This is called amplification.


Electronic noise exists in conductors in the same way and it is the random thermal motion of electrons.
We can certainly hear this random motion as hiss if we turn up the volume in any amplifier when there is no music loud enough to mask it


In the beginning of the 20th  century amplification was made possible by devices called electron tubes where the control of the movement of the electrons is done in the vacuum of the evacuated glass tube.


Since then smaller devices called transistors have been invented which have evolved to be so small that billions if them may exist in the processing chips of a smart phone.


The electron tube or vacuum tube faults make them very attractive to the production and reproduction of music.


Almost always tracing the origin of a hit song we will find more than one electron tube in the signal path from production microphone to the listener loudspeaker.. An obvious contemporay example is the use of the 1947 made Neumann U47 microphone having inside the VF14 electron tube. Such a mic can be seen for example in  the Christina Anguilera video clip on recording Say Something.


A reason for tubes is the way they overload from a music signal mimicing the way our ear - brain overloads. There will always be overload as music is a tremendously dynamic signal and overload is a desirable thing compressing a large dynamic range to small so that one can hear loudly radio in the car without quite passages be masked by noise or louder ones overloading your laptop. The tube is made to overload so that the digital circuitry does not overload abruptly as it runs out of 1s. (11111111.... in a 16 bit coding digital system).


Music is the art and science of conveing emotions from the brain of the composer to the brain of the listener .


In practical terms it consists of melody, bass and harmony.


It consists of repetition and surprise but it's ingredients is melody bass and harmony.


((((( apendix on impedance
If an ant collides on a elephant, not much happens it may just bounce back. They have vastly different mass. In energy flow terms this is called impedance mismatching. A mismatch makes the energy being reflected back. Same when we look our selves to the mirror. Or if we talk with both palms in front of our nose on a non reflecting space like a beach.
If an elephant runs to collide with an ant again there is no much transfer of energy from the point that almost all of the elephants kinetic energy stays within the elephant and may put the elephant in danger if stopping in not done on time.


Difference in impedance is what make the waves bounce back at the end of a open organ pipe. Or reflect at the end of the guitar or piano string fixed at it ends. A similar reflection happens to the walls of a cathedral making the acoustic huge. Similarly as impedance mismatching mirrors on opposite walls make light waves echoes re reflect making the room look huge.


The trapped energy is called standing waves. In the strings the multiple reflections establish a repeating patern which produces the note we hear.


Strings can vibrate in may permissible modes. This produces harmonics.


Harmonics in turns produce the notes of the C major scale.


From 7 notes all music already existing and future can be made.
How we will shortly see. )))))


Melody is the mystery. We do not know where it comes from and it can happen to anyone whether musically educated or not.


Bass as the name signifies comes from the Greek basis meaning root or base and is the foundation of music where all harmony springs from it.[ JS Bach intructions to his students on figured bass]


Harmony is the combination of different notes sounding together.


Since there exist 7 only notes which repeat themselves at different octaves there will be 7 bass notes too.


The natural or common harmony when not something different is specified is produced by adding the 3rd and 5th  (1 3 5 law) note on the right hand. So the bass being C. The right hand can be 1 3 5 ie C E G.


The most famous example would be opening chord of Imagine - John Lennon, bass being C and right hand using the notes C E G as a sequence of E G. Together then C then E G then C and so on to include a rhythm structure. Then after a while the bass becomes F and the natural law of 1 3  5 would r quire F A C, which is exactly what is done and this chord is called F major. Having a song with A on bass (second chord of Alone - Hearts) would require A C E. This time the chord is not called A major but minor due to the asymmetry of the keys of a piano. a to c has fewer semitones steps than c to E.


D on the bass naturally requires D F A an obvious example is the opening chord of Requiem in D minor. - Mozart.


Since there are 7 notes available for the bass there would be 7 chords that can be made (using the 1 3 5 law) and if we normalize any music piece to the C major scale ( using all white keys only we can play with both hands on a piano almost any musical piece ever written with just these 7 chords at the correct order the composer choose.


What makes the beauty of music further flourish is to depart intentionally from the 1 3 5 law to create further colors in our palette. A different code could be 1 4 7. An example is  2nd chord on Requiem - Mozart as the bass plays F and the right hand D A.


We can have many different codes and this is one of the reasons music can have an almost infinite variety even in its micro structure. Some of these combinations like 1 3 5 and 1 4 6 are called consonants and other are called dissonant such as 1 3 9. It does not mean that they do not sound agreeable. A beautiful example of 1 3 9 is third sung word of Close to You - Carpenters (in the sung word birds, the sung G is 9 notes above bass F) . Another example is the first  chord of Just Hold Me - Maria Mena again a 9th chord.


Another example is the  3rd chord of Qui Tollis  from Mass in B minor - J.S.Bach.


Much of the skillful art of music is the balance between consonants and dissonances as J.S. Bach explains and how 7ths and 9ths are prepared for our brain.


 A useful rule is taking the third together with a 9th so 7th.  An example is the 3rd chord of Bachs. Air where the bass plays G the right hand plays the prepared 7th note of the scale (D major scale in this piece) which is  F# and the other instruments play th 3 rd B and D (5th). The reader us reared to the instructions to his students in music by J S BASS.


Orchestration being a subject in itself includes knowledge of masking theory.


An overlooked but extreme,y import knowledge to anyone involved into.making music is the knowledge of the Fletcher Manson curves. These show by experiment how the sensitive of the ear brain mechanism changes according to frequency and most importantly  the intensity level of this frequency.


Having its practical origin to survival a very faint sound pressure level from a crying baby in danger emitting mid frequencies to the most sensitive mid range ear at low levels. The ear surging to catch up in sensitivity at low and high frequencies as iintencity levels increase. An obvious example is that by turning up the volume in a radio we start to hear not only louder but fuller, bass and treble perception coming to play.


If bass and treble frequencies are not reduced during recording or mid boosted by a high quality inductor equalizer  the usually higher intensity in reproduction will make a voice sound bassy boomy and spitty due to bass and high frequency predominance compared to mid range.


Although it is easy to assume that one must record and reproduce flat it proves that one has to deliberately  make a mistake to to counteract natures "mistake " so that the correct natural and pleasing balance results.


This may seem contradictory to signal theory requiring that flat reproduction will produce an undistorted signal. This would be true if our signal path would be from production microphone to reproducing loudspeaker.


Actually the signal path is from  the vocal chords of the performer to the brain of the listener or the brain of the composer to the brain of the listener.


So we  have in our disposal all those molecules of air and electrons to tell them what they should do.

How to hear the true quality of you voice

Find a quiet outdoor place, eg beach, forest ...


Join your palms and touch your small fingers to your nose.


Speak or sing, enjoy!

Happiness Inside Only

1st Pleiades High Cut Filter

Yesterday was made the 1st Pleiades high cut microphone filter inside an XLR adaptor.


The idea was :

to compensate for increased high freequency content due to mic proximity (obstacle effect)


to compensate for Fletcher Manson and voice effort curves


It consisted of only one 220 nanofarad capacitor in parallel with mic output.


Theoretical cutoff 3.5KHz assuming 200ohms Zo of microphone.


Is this still 6db per octave or does it make a reasonant circuit with the Pleiades low cut inductor filter in parallel too?


When it was connected any unnatural hiss left was almost extinct and it was found more desirable to further cut bass for balance. Values up to 25mH were used, (1.27kHz). At an output stage it would round off peaks of instantaneous limiting!


Signal path:


MD421 - Pleiades high cut - Pleiades low cut - Canford input transformer - EF183 with positive bias


Sound had quality of Say Something - Brave New World, Anguilera

Hapiness is Around

Nothing Gets Lost

If you give freely, it will come back in multiple ways.

How to Stop an Addiction

A simpler way to calculate daily dose can be the following:


For example, one smokes 20 cigarettes per day and feels a comfortable dose for next day is 19.


Step 1: Dividing 19:20 = 0.95.
This number can be used to find dosage for every day by multiplication.


Day we start dosage  : 20 cigarettes


Next day : 20 x 0.95 = 19 cigarettes


Day after : 19 x 0.95 = 18.05 cigarettes


Day after : 18.05 x 0.95 = 17.14 cigarettes
..........


Day seven :  20 x 0.95 x 0.95 x 0.95 x 0.95 x 0.95 x 0.95 x 0.95 = 13.9 cigarettes


(Note as time goes by the rate of dosage reduction decreases, greatest reduction is on 1st day)


So if you can comfortably cope the 1st day you should be able to cope all the rest until dosage is 0

How to Stop Any Addiction

Theory : That you want to stop it.

And now to the practical part.

Step 1 : You decide how long it should take you, and you write this time on the horizontal (time axis), example will be given.

Step 2 : You write on top of the vertical axis (dosage axis), what is your current dosage.

Step 3 : You draw an inverse exponential curve as drawn on the example

(An inverse exponential curve has the property that at equal amounts of time the dosage becomes half)

End of story, you follow the dosage as given on the curve, good luck.

(I am not a doctor or you do at your own risk)

Example : Say you smoke 20 cigarettes per day and you choose to have stopped smoking  within 6 months:

By drawing on a large mm paper and dividing each month to 30 days, with a 90 degrees triangular ruler you can calculate cigarette dosage for each day.


This technique has already been used with success on 2 individuals for quitting Cipralex, Entact, Escitalopram antidepressant by measuring each daily dose on a small micro gram electronic weighting scale bought on eBay.

Flying Over Aegean - George Chakiris parts score

A little piece I dreamed of.


Public domain dedication.


Rough demo on YouTube :



https://www.youtube.com/watch?v=Gfo9_u9cjxI</div>

Pleades 4.8V super quiet microphone pre pre amplifier booster with EF183 triode connected and 3.9M positive bias from anode to grid

The idea comes from Hliana who insisted on positively biasing grid to free electrons.


Assigned to public domain by George Chakiris.


This little pre preamplifier makes a voice appear times bigger.


YouTube clip of earlier prototype with 6V lead acid battery and 4R7 dropping Resistor.
https://www.youtube.com/watch?v=xPVtXzmfDR8


Please note heaters are under heated to reduce information obscuring electron cloud.


This prototype was tested with Sennheiser MD421 feeding a Canford  low to high impedance converter (419mH transformer primary) feeding pre pre amplifier feeding a Realistic Disco Mixer at its mic input.


Component list:
4x AAA batteries (through fuse they supply heaters directly and anode through Ra) (neg to cathode)
1x fuse holder (very important to protect yourself and the batteries)
1x 0.8A fuse (will be reduced as heater current should be around 260 mA, initial 500mA)
1x EF183 electron tube (EF183 is vari mu, high gm) (in this amp grid 2 and 3 are connected to Anode)
Ra=15K (10K shown)
Rag=3.9MOhms (positive bias resistor from anode to grid to free electrons)
Ci=220nF ( very important input capacitor to keep grid free )
Co=1uF (output coupling capacitor)


Proximity low cut off can be adjusted by the primary inductance of the input transformer. A Pleiades input transformer can be made with 70 - 300 mH so that extremely detailed and clear vocals can be obtained at a distance of 1-2 inch from microphone. The closer the distance needed the less the inductance making construction easier as fewer primary turns are needed. An excellent example of magnetic core is Magnetec's series of nano crystalline extremely high inductance index toroidal cores.


With just 3 AAA (3.6V) it performed even better and perhaps more quietly but gain was lower. Grid bias was close to 0 compared to  -0.4V when 4 AAA were used due to increased negative electron cloud making cathode more positive with respect to grid?)


Very nice performing with electric bass too.
Signal Path:
Yamaha electric bass - Pleiades pre pre - 50K to 500Ohms impedance converter - Realistic Disco mixer mic input
Extremely quiet bass operation and great tone




Schematic of pre preamplifier showing experiments of connecting Grid resistor to various points. Maximum anode current was as expected obtained by having the other side connected to Anode. This does not mean that grid is positive but it is certainly less negative. Being positive or not depends on cathode temperature, lower temperatures reduce electron boiling cloud and this can make grid positive with respect to cathode.

Pleiades Electra 1.3V electron tube pre preamplifier with CV2269 electrometer tube and positive grid bias from positive heater to grid

Pleiades Electra 2 picture with wiring shown