ne, jus neteisus. Net wikipedijoje apie stabilizatorius parasyta apie si reikala (ne apie jus :) ). Mastom taip. Prietaisui reikia 1A sroves ir 5V. Pradinis saltinis blogiausiu atveju (ijungtas variklis)- 14V. Kadangi tai "linear regulator" kuris jungiasi nuosekliai, tai per ji teka ta pati srove kaip ir per apkrova, t.y. 1A. Pagal kazkuri ten rodos kirchofo desni, visu saltiniu itampu suma lygi visu vartoju itampu sumai. T.y. saltinia viso 14V, vartotojai 5V ir xV ant stabilizatoriaus. 14-5=9V. Energija niekur nedingsta, vadinasi ji sunaudojama ir virsta zemiausia savo forma- siluma. (cia jau fizikos desniai- tvermes ir gal dar entropijos). P=U*I=9*1=9W. Tiek silumos gausim. Atviras TO-220 korpusas gali issipinduliuoti i erdve (normaliom salygom) apie 1W silumos, taciau jo korpusas ten ikaista gal net iki 100 laipsniu. Prie daugiau laipsniu, korpusas gal daugiau neikais, bet kristalas viduje jau bus kokiu 125 ir viskas nafig suges. Todel dedamas radiatorius. Taciau del silumines varzos vistiek ribojasi galia. Yra net toks terminas- maksimali galia uzdejus begalinio dydzio radiatoriu... Bet tuos 9W gal TO-220 dar sugeba issipinduliuoti. Dabar apie low-dropout migla ir nesusipratimus. Paprastas senoviska mikroschema kaip 78xx ar LM317/LM117 turi tureti kaip minimum 2V itampu skirtumus (drop) kad veiktu stabiliai (gal daugiau). Siuolaikines "low dropout" mikroschemos prasom gal net maziau volto. Taciau tai nereiskia, kad ant jos ses tiek voltu. Paprasciausiai tai rodo, prie kokio skirtumo mikroschema veikia. Pvz. jei drop out 3V, tai is 5V as negaliu darytis sau 3.3V stabilizatoriaus ir turiu sildyti gamta stabilizuodamas is aukstesnis itampos, sakysim 12V ar 9V. Turedamas low dropout stabilizatoriu as galiu imti 5V ir nusistabilizuoti iki 3.3V (jei dropout < 1.7V) Realiai esu susidures, kad del to, kai kuriuose kiniskuose aparatuose CPU core (~1.25V) gaminamas is 5V o ne is logiskesniu 3.3V. Ko pasekoje naudojamos pigesnes mikroschemos, taciau netaupoma elektra ir siluma. Beja vokiskai ne bum bum. O angliskoje prasom: http://en.wikipedia.org/wiki/78xx a.. As they are based on a linear regulator design, the input current required is always the same as the output current. As the input voltage must always be higher than the output voltage, this means that the total power (voltage multiplied by current) going into the 78xx will be more than the output power provided. The extra input power is dissipated as heat. This means both that for some applications an adequate heatsink must be provided, and also that a (often substantial) portion of the input power is wasted during the process, rendering them less efficient than some other types of power supplies. When the input voltage is significantly higher than the regulated output voltage (for example, powering a 7805 using a 24 volt power source), this inefficiency can be a significant issue. http://en.wikipedia.org/wiki/Linear_regulator The resistance of the regulator varies in accordance with the load resulting in a constant output voltage. ... The regulating device is made to act like a variable resistor, continuously adjusting a voltage divider network to maintain a constant output voltage... ... a.. Series regulators are the more common form. The series regulator works by providing a path from the supply voltage to the load through a variable resistance (the main transistor is in the "top half" of the voltage divider). The power dissipated by the regulating device is equal to the power supply output current times the voltage drop in the regulating device. Shunto reguliatorius retai naudojamas ir dazniau kai mazos galios. TL431 geras pavyzdukas. http://www.ti.com/product/tl431 Su shunto reguliatorius siluma issiskiria saltinio viduje (pas auto cia jau problematiska) ir blogiausia situacija gautusi atjungus apkrova. WOW! grafomanijos priepuolis gavosi. -- Bye, Levas -- http://www.vabolis.lt "Kantega" <kf@kantega.org> wrote in message news:jn9m3v$46n$1@trimpas.omnitel.net... >> tomtopas valgys tikrai daugiau nei 1A. >> >> 14-5=9V. >> >> 9W silumos minimum bus... > > Pradejau mastyt ar tokie skaiciavimai yra teisingi. Juk LMas nera "cross regulator", kuris visa pertekline energija pavercia i siluma, tam kad nusodint saltini iki reikiamos itampos. Jis juk yra nuosekliai jungiamas reguliatorius, ant kurio krenta 0,5V itampa o srove tarkim 1A max. Gaunasi 0,5W? Ar galima taip skaiciuot? > Vokiska vikipedija biski aiskina apie lygegrecius (querregler) ir nuoseklius (laengsregler) reguliatorius. Angliska deja apie juos neuzsimena: > http://de.wikipedia.org/wiki/Linearregler#Lineare_Regler > > p.s.Man tiesiog idomu kaip teisingai skaiciuot, o ne "varyt" ant taves :)