dunavko

pec bi trebala da bude za eksperimente sa keramikom,probna,malih gabarita kao lonac od 5 litara a unutra alumina 5-6 cm -100-150 millilitara.,izmedju izolacija.elektro zbog lakse regulacije.pid regulator.ssr.inertna atmosfera po mogucstvu-problem dihtovanje.imam herausove dve ali su mi veliki problem spojevi grejaca i dovodne zice.odradi 20 -30 ciklusa i spoj postane los.moram da izvedem kanthal zicu spolja a to je jako pipavo i skupljam snagu i zivce vec godinu dana...

pa da , termo par,zebekov efekat Type R Type R (87%Pt/13%Rh–Pt, by weight) thermocouples are used up to 1600 °C. Type S Type S (90%Pt/10%Rh–Pt, by weight) thermocouples, similar to type R, are used up to 1600 ° nema trika ,max temperatura peci je koliko ide grejna zica ,kanthal,ranije je bio sa prefiksom a , b ,plus i sada ide do 1400 c i to odredjeni broj ciklusa grejanja-hladjenja.pravio sam razne peci pa i u vakuumu-sa tantalom,grafitom,volframom kao grejacima i sa vrlo visokim temp.merili smo optickim pirometrom.

majstore,kako dobijas i meris tu visoku temperaturu.svi kanthali su tu negde na granici i merenje sa termospregom verovatno pt-rhod ,typ r ili s ili slicno .meni treba nesto oko 1400C a da bude ekonomski podnosljivo,da ne bude u vakuumu.a za ovu keramiku svaka cast a i za glazure.ovde kod mene na obali dunava ima kaolina sa primesama ali kada se dublje zakopa ide veca cistoca.pronalazili smo ostatke rimske keramike-grncarije .golubije sive boje,ima neku zrnastu strukturu.pitanje na kojoj je temperaturi peceno i da li ima silikata u njoj.

valjda naprave al.spulnu pa namotaju zicu pa onda nacentriraju sa folijom i zalepe.pre toga ga odlepe sa nekim rastvaracem - acetonom,nitrom,itd...siguran sam da to rade kvalitetno.meni treba da napravim sa tim zvucnikom neku kutiju a sve bih to gurao sa triodom 6s4s sa snagom max od 3 w ,suva klasa A.dodao bih one iskrine elipse pa bi tu trebala neka skretnica,mozda samo kon.pa ako neko ima neko iskustvo....

zvao,1500 din po komadu .gledao sam na netu aplikacije sa tim zvucnicima .ima dobru iskoristivost,valjda 98 db.sirokopojasni . jel neko nesto radio sa njima,ima li neko svoje iskustvo,kakva, kutija, itd...

jel ima neko da mota zvucnike u bgd. da ne idem dalje.ima 2 komada rft 12 " , L3401 6ohm 12,5W a da mi se isplati.

kupujem sirokopojasni zvucnik 12 inca 50w i vise, ako ima i dva komada .oni niski kopija philipsa sa trubicom 50w odgovaraju

silumin verovatno.kod takvih varova se ne skida - obradjuje materijal koji je nabacen-zavaren na predmetu koji se vari da bi bio jaci. bila je nekad jedna tehnika poliranja gde se valjda alu. prah kroz diznu sa nekim gasom koji je zapaljiv "prskao" po recimo bloku motora i tu se dobija vrlo lep efekat sjaja.to je nekad radio neki majstor iz sarajevske ulice pre jedno 40 godina i secam se bmw motora koje je on radio ,idi begaj...ala bi bila neka sasija za neko cevno pojacalo pa sa tom tehnikom....

pa jel spialter ili nesto na bazi aluminijuma -dur ili neka silumina .kako je zavario? jel mig-mag -zica kroz crevo ili tig -zicu sa strane dodaje drugom rukom .da nije map gas pa specijalnu elektrodu za alu.jesi li gledo sta je varioc radio ili si gledao u sekretaricu ?

jesi siguran da je nogica od spialtera .da nije od duralu.spialter nema neke meh.osobine za tako nesto da drzi teret i on se najvise lemi jer ima zinka u leguri najvise.imas na netu. to sto ste grejali mozda je bilo pogresno jer cink se topi na niskoj temp. - ako je to spialter.

moj vanbrodski motor honda iz 78 godine 4 takta 2 cilindra 159 kubika daje pri punoj turazi-na znam kolika je ali sigurno je mnogo manja od ovijeh zujalica ima deklarisanu snagu na elisi od 7.5 hp.iz 78 godine radi ko momak pa ti vidi.

da nisi nesto pobrko sa snagom tog motorina - 32hp?

i ovo imam..moze za nas muzej nauke i tehnike da se vidi sta smi i mi radili

i ovo imam...

naleteo na oglas pa ajde ponovo,250 eura

sve ostalo isto

imam vise signal generatora low distortion ali nijedan nije sa prefiksom ultra,evo na primer ovaj: HP / Agilent 3314A 20MHz Function Generator, Refurbished Lin/Log sweeps AM/FM/VCO Phase lock XN and ÷N Gate and counted burst 1/2 cycle mode Arbitrary waveform generator Available Options, Below Hewlett Packard 3314A Shown The 3314A is a Function/Waveform Generator with the precision and versatility to produce numerous waveforms. Its feature set includes accurate sine, square, and triangle waves, with ramps and pulses available using variable symmetry. Additional features include counted bursts, gate, lin/log sweeps, AM, FM/VCO, dc offset, and phase lock. For increased versatility, the Arbitrary waveform mode allows a countless number of user defined waveforms. Since complete programmability is provided, all of these capabilities are available for ATE systems, as well as bench applications. Precise Functions Burst and Gate 1/2 Cycle + "Integer" Phase Lock Modes Modulation and Sweep Arbitrary Waveforms Two Sources in One Source for Your System Arbs Made Easy Precise Functions The 3314A provides sine, square and triangle waveforms from 0.001 Hz to 19.99 MHz with an amplitude range of 0.01 mV to 10 Vp-p into 50 Ω, with optional 30 Vp-p into > 500 Ω. Continuous waveforms are provided with high accuracy and low distortion, with frequency accuracy on the upper ranges of 0.01% and sine disortion < -55 dBc to 50 kHz. ili ovaj hp The Model 654A is a stable, low distortion sine-wave signal source

treba mi samo za lampe, i valjda ce da radi-jos ga nisam upalio,u nekoj sam guzvi.Ne tezim da se bavim bas vrhunskim merenjima.imam i uputstvo za njega na ingleskom,jbg,al sta je tuje.ima i nesto na youtube pa cu polakoo..

Understanding, Calculating, and Measuring Total Harmonic Distortion (THD) February 20, 2017 by David Williams Total harmonic distortion (THD) is a measurement that tells you how much of the distortion of a voltage or current is due to harmonics in the signal. THD is an important aspect in audio, communications, and power systems and should typically, but not always, be as low as possible. Introduction Harmonics or harmonic frequencies of a periodic voltage or current are frequency components in the signal that are at integer multiples of the frequency of the main signal. This is the basic outcome that Fourier analysis of a periodic signal shows. Harmonic distortion is the distortion of the signal due to these harmonics. A voltage or current that is purely sinusoidal has no harmonic distortion because it is a signal consisting of a single frequency. A voltage or current that is periodic but not purely sinusoidal will have higher frequency components in it contributing to the harmonic distortion of the signal. In general, the less that a periodic signal looks like a sine wave, the stronger the harmonic components are and the more harmonic distortion it will have. So, a purely sinusoidal signal has no distortion while a square wave, which is periodic but does not look sinusoidal at all, will have lots of harmonic distortion. In the real world, of course, sinusoidal voltages and currents are not perfectly sinusoidal; some amount of harmonic distortion will be present. Figures 1 and 2 provide visual comparisons, in the time domain and the frequency domain, of a sinusoidal voltage and a square wave voltage. Figure 1. A sinusoidal voltage and a square wave voltage in the time domain. Figure 2. A sinusoidal voltage and a square wave voltage in the frequency domain; only the square wave has peaks at the harmonic frequencies. It is easy to see the harmonic distortion when examining the time domain and frequency domain representations of a square wave, but it is also important to be able to quantify harmonic distortion. The next section shows how to do that with the metric of total harmonic distortion. Calculating Total Harmonic Distortion THD is defined as the ratio of the equivalent root mean square (RMS) voltage of all the harmonic frequencies (from the 2nd harmonic on) over the RMS voltage of the fundamental frequency (the fundamental frequency is the main frequency of the signal, i.e., the frequency that you would identify if examining the signal with an oscilloscope). Equation 1 shows the mathematical definition of THD (note that voltage is used in this equation, but current could be used instead): THD=∑∞n=2V2n_rms−−−−−−−−−−√Vfund_rmsTHD=∑n=2∞Vn_rms2Vfund_rms Equation 1 Vn_rmsVn_rms is the RMS voltage of the nth harmonic Vfund_rmsVfund_rms is the RMS voltage of the fundamental frequency Since the amplitudes of the harmonics are needed to calculate the THD, Fourier analysis can be used to help determine THD. To see this application of Fourier analysis, let’s look at the simple example of a 50% duty cycle square wave. The Fourier series representation of a 50% duty cycle square wave is the following: vsquare(t)=4π∑n=1,3,5...∞sin(2nπft)nvsquare(t)=4π∑n=1,3,5...∞sin(2nπft)n Equation 2 And in expanded form, this is: vsquare(t)=4πsin(2πft)+43πsin(6πft)+45πsin(10πft)+...+4nπsin(2nπft)vsquare(t)=4πsin(2πft)+43πsin(6πft)+45πsin(10πft)+...+4nπsin(2nπft) Equation 3 The expanded form is useful to look at because it highlights the peak voltage (Vpk) of each frequency component, and the THD can be calculated by determining the RMS value (i.e., Vpk2–√Vpk2 ) of each frequency component and plugging them all in to Equation 1: THDsquare=(432√π)2+(452√π)2+(472√π)2+...+(4n2√π)2−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−√42√πTHDsquare=(432π)2+(452π)2+(472π)2+...+(4n2π)242π Equation 4 This equation is starting to get unwieldy, but one thing to notice is that every term in the expression has a 42–√π42π component. This component can be factored out, and since it appears in both the numerator and denominator, it actually cancels out, which leaves the expression for THD of a square wave as follows: THDsquare=∑∞n=3,5,...1n2−−−−−−−−−√1=132+152+172+...+1(n)2−−−−−−−−−−−−−−−−−−−−−√THDsquare=∑n=3,5,...∞1n21=132+152+172+...+1(n)2 Equation 5 To calculate the THD from this expression requires a tricky little bit of mathematics. If the summation under the square root in Equation 5 started at n=1, then it would be a convergent series that adds up to π28π28 : ∑n=1,3,5...∞1n2=π28∑n=1,3,5...∞1n2=π28 Equation 6 The only difference between the expression in Equation 6 and the one in the THD calculation of Equation 5 (∑n=3,5,...∞1n2)(∑n=3,5,...∞1n2) is the value of 1n21n2 when n is 1. Since this value is 1, the summation in the THD expression can be re-written as: ∑n=3,5,...∞1n2=∑n=1,3,5...∞1n2−1=π28−1∑n=3,5,...∞1n2=∑n=1,3,5...∞1n2−1=π28−1 Equation 7 Finally, plugging this equation back into the THD equation for the square wave (Equation 5) gives: THDsquare=π28−1−−−−−−√≈0.483THDsquare=π28−1≈0.483 Equation 8 Our assumption at the beginning that a square wave has a lot of harmonic distortion was based on visually examining the square wave in the time and the frequency domain. The calculations that we just went through confirm our assumption. A square wave actually has about 48.3% total harmonic distortion meaning that the RMS of the harmonics is about 48.3% of the RMS of the fundamental frequency. Measuring Total Harmonic Distortion Calculating theoretical THD can be a good exercise, but it can be a lot of work, and in practice, you aren’t going to get an ideal signal (e.g., a perfect square wave) anyway. The outcome of these calculations can therefore only give an approximation for the THD that you might get for a given signal type. In practice, THD must be measured to obtain the RMS value of the fundamental frequency and all of the harmonics. This measurement can be done in a couple of ways. In the first method, filters can be used to split the signal into two parts: a signal with all of the harmonics filtered out leaving just the fundamental frequency, and a signal with the fundamental frequency filtered out leaving all of the harmonics. Then the RMS value of each of those two parts can be measured and the THD calculated: THD=VRMS_Without_FundamentalVRMS_FundamentalTHD=VRMS_Without_FundamentalVRMS_Fundamental The upside of this method is that it is easy to perform these measurements. The downside is that noise will also be included in the measurement so you actually get a measurement of THD plus noise (although in audio systems THD+noise is actually an important measurement too). The second method for measuring THD is to measure the amplitude of the fundamental frequency and each harmonic and then use those measurements to calculate THD using Equation 1. This measurement can easily be done using a spectrum analyzer or a THD analyzer which will execute Equation 1 automatically. An alternative measurement technique is to capture voltage or current data and then perform a Fourier transform on the data collected. The example below outlines how this second method is used. Example THD Measurement The example block diagram in figure 3 shows a 1 kHz sine wave passing through an amplifier to create a new 1kHz sine wave that has some crossover distortion. This new wave is fed in to a spectrum analyzer which gives a graphical display of the amplitude of a number of the harmonics. Figure 3. A system that introduces crossover distortion into a signal. Zooming in on the frequency spectrum of the distorted sine wave output, we can see the amplitudes at several of the harmonic frequencies: Figure 4. Frequency spectrum of sinusoidal voltage with crossover distortion. From this frequency spectrum, I manually measured the amplitude of each of the harmonic frequencies and recorded the data in the table below: Amplitudes of Harmonics of Distorted Sine Wave Harmonic Amplitude 1 3.08V 3 0.308V 5 0.159V 7 0.090V 9 0.0487V 11 0.0253V 13 0.0164V 15 0.010V The amplitudes of even-numbered harmonics and harmonics above the 15th are nearly 0, so I didn’t include them in my calculation. The measured amplitudes are plugged in to the THD equation: THD=0.3082+0.1592+0.0902+0.04872+0.02532+0.01642+0.0102−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−√3.08THD=0.3082+0.1592+0.0902+0.04872+0.02532+0.01642+0.01023.08 (note that I am able to use the voltage amplitudes instead of RMS voltage because VRMS=Vp2–√VRMS=Vp2 and since the 2–√2 occurs in all terms, it can be factored out and cancelled). This calculation gives a THD of 0.118 or 11.8%. Of course a THD analyzer would automate the process of calculating THD from the amplitudes of the harmonics. Using a THD analyzer for this signal gives a value of 11.9%, which confirms the accuracy of the manual method that I just went through. Final Words This article has provided some background about THD and how to determine it, both theoretically and in a real (simulated) system. But it has not discussed the kinds of systems where THD is an important measurement. THD is important in several types of systems, including power systems, where a low THD means higher power factor, lower peak currents, and higher efficiency; audio systems, where low THD means that the audio signal is a more faithful reproduction of the original recording; and communication systems, where low THD means less interference with other devices and higher transmit power for the signal of interest. Look for future articles where I will go into more detail about these specific types of systems.

to znaci da je za preciznija merenja ovaj hp334a zastareo?

Nabavio sam skoro HP 334A Distortion Analyzer An audio frequency distortion analyzer basically is a precise AC volt-meter with very flat frequency response from 10Hz to 1MHz ( +/- 0.05 db). Distortion measurement takes two voltage readings where the first reading includes fundamental and harmonics, the second reading includes only the harmonics. The percentage distortion is the ratio of these two readings. (2nd reading/1st reading). If the 1st reading being set to 1 unit, the 2nd reading is the answer. The HP334A solid stated distortion analyzers were probably the most user-friendly harmonic distortion analyzers ever made. The automatic nulling design is helpful and efficient, which speeds up the time consuming portion of distortion measurements. This model includes two control loops that automatically phase lock the bridge circuit at fundamental frequency so that only harmonics can pass the bridge. This machine can measure audio frequency (5Hz to 600KHz) THD (Total Harmonic Distortion) down to 0.1% full scale, very useful for audio amplifiers and tube gears. Electrical features : Voltage Measurement: 300uV to 300V RMS Full Scale Residual noise : 25uV 600 OHM Frequency Range: 5 Hz to 600 KHz. Distortion Levels: 0.1% to 100% full scale. Auto Nulling AM detector (334A only) Power – 115 or 230 VAC Dimenions – 17 X 13 X 6 inchesMore information about HP 334A/333A The HP333A/334A were produced from late 60’s to 70’s with very good build quality, such good build quality is hard to find nowadays. I tested and sold many 333A/334A units. The most interesting case is that the machine displays 0.05% distortion while the actual signal distortion is 0.02%, this is because the rejection amplifier can not well clear the fundamental frequency, how to locate the 0.03% difference is a funny job but of course not simple as just contact cleaning. Also a good 333A/334A machine should give same reading in two ranges for an overlap frequency, for example a 5.5KHz signal should be measured at both x100 or x1K range with SAME result. The HEART of HP333A/334A is the auto nulling 90 degree phase spliter, it can accurately split the fundamental frequency into two components :- real axis and imaginary axis (also known as square root of negative one axis). These two voltage signal maintain the bridge balance to eliminate fundamental frequency. Thank you for visiting! Probacu ovih dana dal radi.jer neko ima iskustva sa merenjima ove vrste?

i jednog dana vanzemaljci prilikom ispitivanja ostataka jahte na osnovu otisaka guzpapilarnih linija koje se nalaze na jarbolu od glatkog tvrdog metelnog materijala (da je grafit ne bi mogli) putem intermaterijalnog sintetizatora mekog tkiva sintetizuju nosioce otisaka..I ...dalje se fucka...Zakljucak se neminovno sam namece. Dobra zastita metala pruza zadovoljstvo na kratko ali kvari razvoj nepredvidljivih dogadjaja u buducnosti na taj nacin sto ih pretvara u predvidljivost.

ovaj strugar je majstor ako je ovako obradio bronzu,nesto me podseca na mesing po boji.probaj negde da zagrebes sa turpijom i ako ostavi trag onda je to neka "meka bronza".iako ne menja na stvari,za onaj ruski recept je svejedno.

bronza se mnogo redje srece nego mesing a i sama namena joj je za lezajeve -grafitna bronza.ima situacija u praksi gde je mnogo bolja nego lageri . a i mnogo teze se obradjuje nego mesing .a i obe legure spolja su slicne , eto to je razlog zasto sam pomislio da je mesing .kod nas u Srbiji mnogo se koristio mesing pogotovo u odrzavanju raznih masina po fabrikama, jer je lak za obradu a i bio je jeftin - zbog rudnika bakra .koliko puta sam posmatrao reakcije stranaca sa kojima smo saradjivali ,nemci,italijani,rusi,japanci itd kada su videli koliko mnogo koristimo mesing u odrzavanju .sada se situacija malo promenila .gledam po otpadima,godinama unazad ogromne kolicine bakra i mesinga, koje se otkupljuju za dobre pare .jedno vreme je cena na berzi bila manja nego sto su ovde placali bakar.pokusavao sam da dokucim razlog i jedino prihvatljivo objasnjenje je u tome da se u tom nasem bakru nalaze primese plemenitih metala i da je to neko pametan organizovao i da te metale izvlaci boljom tehnologijom . ko bi ga znao....samo mi se cini da je zvuk bio bolji kada je struja tekla na onim starim socijalistickim zicama iz Bora.

da ne poveruje covek - bronza. ali dobro.evo ruski recept sa benzotriazolom ,to je hemijska reakcija.Valjda ima neki hemicar na sajtu da to malo bolje objasni. Защита меди, медных сплавов и серебра. Для защиты от коррозии предметов из меди, медных сплавов и серебра музейными реставрационными лабораториями всего мира, используется контактный ингибитор бензотриазол. Бензотриазол (БТА) C6H5N3 peaгирует с солями одновалентной и двухвалентной меди и образует полимерные соединения, которые не растворяются в воде и устойчивы при температуре до 200°С. Благодаря образованию новых нерастворимых соединений бензотриазол задерживает также развитие «бронзовой болезни». Зарубежные реставраторы рекомендуют защищать бензотриазолом как очищенные археологические предметы, так и предметы, на которых сохранен коррозионный слой или благородная патина. Потемнение отполированных бронзовых, медных и серебрянных музейных предметов (посуда, осветительные приборы) также может быть замедлено обработкой бензотриазолом. Как опыт показывает, что бензотриазол защищает музейные предметы из цветных металлов и очищенные археологические предметы. Металл, на котором активный коррозионный процесс уже начался, или предметы, с которых коррозионные продукты удалены не полностью, бензотриазолом не защищаются. Очищенные от загрязнения и обезжиренные предметы погружаются в 3% водный раствор БТА на 6 часов. Температура раствора должна быть не менее 20°С. Затем предметы высушивают и протирают мягкой хлопчатобумажной тканью, смоченной в дистиллированной воде для удаления излишков бензотриазола. Дальше консервация может проводиться обычными способами. Музейные крупные предметы обрабатываются нагретым до 50°С 3% раствором смачиванием. Такая обработка проводится несколько раз с промежуточной сушкой при комнатной температуре. При работе с бензотриазолом надо помнить, что он канцерогенен, поэтому необходимо исключать прямое попадание его на кожу и всю работу с ним проводить в перчатках. К серудержащим ингибиторам, применяемым для защиты медных сплавов и серебра, относится 2-меркаптобензотиазол (МБТ), известный в промышленности как "каптакс". Обработка меди и бронзы 3% спиртовым раствором МБТ позволяет резко повысить коррозионную стойкость металла. Лучше результаты получаются при погружении предмета в раствор с температурой 60- 80 градусов С на 30 мин. В некоторых случаях МБТ оказывается эффектнеенее бензотриазола. Среди неорганических ингибиторов, применяющихся для защиты цветных металлов, ведущее место принадлежит хроматам. Хроматная пассивация является одним из наиболее экономичных способов защиты от потускнения меди и серебра, а также сплавов на их основе. Пассивирование проводят как с наложением катодного тока, так и без него. Состав электролита и режим работы при хроматировании могут колебаться в широких пределах без ухудшения защитных свойств получаемых пленок. Медь и медные сплавы выдерживают в течение нескольких минут в растворе содержащем. I г/л хромовой кислоты. Образующаяся при этом пленка обладает высоким сопротивлением к воздействию влаги, сероводорода, солевых растворов. Серебряные изделия надежно пассивируют при наложении катодного тока в электролите, содержащем 20-40 г/л бихроматй натрия 20 г/л - едкого натра и 40 г/л карбоната калия, плотность тока 0,1 а/см2, время выдержки - 40-60 сек., температура раствора - комнатная. Простое погружение в чистый раствор хромового ангидрида или бихромата без применения тока также позволяет запассивировать серебро. Эти растворы должны быть свободны от посторонних кислот. Хорошие результаты получает при двойной обработке: сначала катодной, а затем ополаскиванием в чистом растворе хромового ангидрида или бихромата. Хроматы и бихроматы вредно действуют на кожу, пары их разъедают дыхательные пути. Поэтому необходимо работать в резиновых перчатках и под тягой.