I^2R Otpornost - Snaga otpornika u zavisnosti od specifične toplote materijala - II deo.

Ovo je nastavak na I^2R Otpornost blog posta, u kojem prikazujem ono što sam naveo u prvom blog postu o otpornosti a to je da snaga istog zavisi od materijala od kojeg se otpornik proizvodi. Ranije sam nabavio knjigu preko InfoElektronika magazina o Merenju otpornosti i generalno o otpornosti, iz koje sam preuzeo odličnu jednačinu snage koja se menja u diferencijalu vremena. Ovde navodim istu uz objašnjenje, ali isto tako navodim i primer vezan za štampane pločice i temperaturni odnos bakra i tinol žice, iz kog razloga pogledajte u video klipu.

Video klip - prikaz jednačine snage otpornika koja zavisi od više faktora a jedan od njih je i specifična toplota materiala od kojeg je otpornik napravljen. Datu jednačinu sam prikazao dole u nastavku blog posta uz naznaku da je preuzeta iz knjige Električna otpornost - pojava i merenje koju možete nabaviti preko zvaničnog web sajte InfoElektronika, naveden je naravno samo deo.

Jednačina snage koja se menja u diferencijalu vremena. Jasno se vidi da je snaga otpornika kontinualna funkcija vremena i prikazuje promenu iste čim se na otpornika dovede snaga tj. konstantni napon i konstantna struja. Jedan od faktora je i specifična toplota materijala od kojeg je otpornik proizveden. Ovo je preuzeto iz knjige Električna otpornost - pojava i merenje, koju možete nabaviti preko InfoElektronika magazina.
Primer ugljenoslojnog otpornika, primer preuzet sa web site-a: M&G Electronic

Primer metal film otpornika, primer preuzet sa web site-a: M&G Electronic

Primer keramičkog otpornika, primer preuzet sa web site-a: M&G Electronic

Primer otpornika sa hladnjakom, primer preuzet sa web site-a: M&G Electronic. Ovaj
primer otpornika je dobar jer poseduje hladnjaka, sa isimt zapravo radi se odstranjivanje viška toplote sa istog kako bi se snaga otpornika održavala u željenoj dizajniranoj vrednosti, jer promena snage nastaje od samog trenutka kada kroz otpornik protiče električna struja. Na ovakav hladnjak se ili eksterno montira pasivno halđenje ili se poveže na PCB a zatim se toplota odvodi kroz bakarne žice na GROUND.

Related articles:

Autor: Vladimir Savić


Comments

Post a Comment

Popular posts from this blog

Electrolytic capacitors and design rules

Image
This article is in tended t o ex plain the bases about electrolytic capacitor , where t he y are used, basic construction, RLC circuit and much more. This is a fir st article about capacit ors and this article is based on zilsel-invent previous article about low pass filters at the following link : Low pass filter and voltage stabilization Electrolytic capacitors and design rules T he f igure #2 presents already used electrolytic capacitors. As we can see electrolytic capacitor is polarized device which means that it is important to pay attention during capacitor assembling to the PCB (printed circuit board). Depending on the capacitor manufactures, in some cases negative lead is marked with a negative sign , and in some cases positive lead (capacitor pin) is marked with a plus sign . Beside polarization mark, there are also labels about capacitance (for example 470 microfarads ) and maximum allowed voltage (for example 10V). The maximum allowed voltage is important parameter r
Read more

Fake VC830L digital multimeter

Image
This article is intended to explain some bad things about cheap digital multimeters since these devices are available in large quantities in Serbia. The key point of this article is security since cheap digital multimeters are not tested/produced according to standards. VC830L is one digital multimeter available in electronics distribution stores in Serbia, but we will avoid company names, since this article is more about “ pay attention before you buy ” cheap digital multimeter. The VC830L is about 10 euros, you cannot expect too much, but if you are not able to buy professional digital multimeter which costs over 100 euros, you will certainly buy the cheap one. Front mask: VC830L digital multimeter. The part interested for us is security so let see what we actually have regarding VC830L digital multimeter. It has three input connectors, starting from the left side: we have connector for 10 amps, common connector (COM) and the right one intended for voltage, r
Read more

How to design LM324 Astable Multivibrator

Image
This blog post is intended to describe how astable multivibrator works based on LM324 operational amplifier, RC timer and positive voltage divider circuits. This is one way to implement astable multivibrator since additional options are available like: specialized signal generators or 555 timer integrated circuit configured to work as an astable multivibrator . There are two states related to astable multivibrator based on RC timer or an analog timer (there is also a digital timer integrated into the microcontroller for example, but in general, digital timers are based on astable multivibrators implemented with quartz or resonator external oscillators, since digital timers count PWM /clock oscilations . Anyway, there are different types of astable multivibrators in order to provide clock cycles): charging and discharging. Charging   To describe charging state we will start from beginning with the completely discharged capacitor C (it has zero volts between p
Read more