LED ?????? ??? ???? ???? ?? ????? ?????

[Neo]

Den oya normal filament ekak thiyena bulb ekak ganna. Okata yavana darava adu karana kota intensity eka adu karanna puluvanne. Namuth LED ekaka ehema behe. NP junction eke bias current eka nolebunoth darava galanne nethi ekane ekata hethuva. Meva ogollo danna samanya deval. Rksk physics nuth karala thiyenava kiyanne ova okkoma dannavane.

Ethakota apita samahara velavata sidda venava LED vala alokaya adu vedi karanna. Meka kohomada karanne? Meka karana kramaya thamai oya Rksk kiyala thiyenne. Ekathara frequency ekakin oya LED eka on off vena akarayata salassanava. Ema frequency eke duty cycle eken eka avarthayakadi On vela thiyena prathishathaya thiranaya karanava. Duty cycle eka 90% kiyala kiwwoth, ekiyanne ara 5KHz frequency eke, eka avarthayakadi 90% kalayak LED eka On vi thebenava, 10% kalayak LED eka Off vela thiyenava kiyana eka. Kalayen kiwwoth, 5KHz kiyanne, eka avarthayak 1/5000 seconds. Ekiyanne 200uS. Ekiyanne 200uS valin 90% = 180uS kalayak LED On venava. 20uS kalayak Off venava. Den api thathparayak selakuvoth, total 900mS kalayak LED eka delvi thiyenava, 100mS kalayak LED eka off vela thiyenava.

Minis esata (human eye) oka echcharama noticeable nehe. Eka nisa eliya adu vima etharama therenne nehe. Hebei duty cycle eka adu karala, LED eka nivi pavathina kalaya vedi karoth, Eliya adu vima therennna patan gannava.

Den api balamu life eka vedi vena akaraya. 10,000 hrs life eka define karala thiyena LED ekak gamu. Oka api kalin discuss karapu PWM use karoth life eka 10,000 x 110 / 100 = 11,000 vedi karaganna puluvan.

Vede pehedilida? PWM thiyena microcontroller ekak aran me vede bohoma pahasuven onema kenekta karanna puluvan.

[Rksk]

Thank you for great explain.

[nipunalanka]

e kiyanne led ekakata frequency eka wadi kaloth bulb eke ayu kale wadi wenawa kiyana ekada?

[Neo]

Frequency eka peththen hithanavata vada hithanna, kochchara vela bulb eka nivila thiyenavada kiyala. Thathparayak eka digata paththu venavata vada, 500 msec paththu vela 500 msec nivila thibunoth ayu kalaya deguna venava neda?

[nipunalanka]

10,000 x 110 / 100 = 11,000
meeke 110/100 kiyala gaththe y? e mokadda PWM kiyanne mokadda?

[Neo]

Ekadigata paththu venne nethuva, 900msec paththu vela thibila 100msec nivila thiyena kota, 10% valin ayu kalaya ithiri venava neda? Anna e 10% mulu ayu kalayata ekathu karanna. Ethakota bulb eke sandahan mulu ayu kalaya * 110 / 100 lebenava.

[nipunalanka]

ethakota 20ms paththuwenna hadanawa bulb eka e kiyanne 20ms paththu wenawa 20ms niwenwa ethakota okkoma 50 ne ethakota ?

[Nandika]

nipunalanka,

mehemane...
mama mulinma duty cycle 1 gana kiyannamko...
api yam square wave 1k gaththahama aoita e wavw eke uparima(max) saha awama(min) agayak balanna puluwan...

min max of square wave.png (3.25 KiB) Viewed 8310 times

namuth me wave ekedi yam karyayak(Duty) karanne uparima agaya witharai...api duty cucle kiyanne mulu awartha kalayen menna me karyayak(Duty) karana kalaya prathishathayak widiyata aragena...
hithanna, square wave ekaka awartha kalaya 60mS kiyala eken uparima wela thiyena kalaya(Duty ekak karana kalaya) 20mS...mahatha rupe widiyata apita eka penwanna puluwan...

min max.png (2.92 KiB) Viewed 8310 times

dan api meke Duty Cycle 1 balamu....
Duty Cycle= uparima vi pawathina kalaya/mulu awartha kalaya*100%
me wave ekedi,
Duty cycle=60mS/80mS*100%=75%
me duty cycle ekata wave eke sankayathay balapamak na...Amplitude eka balapanneth na...
balapanne karana 2i
1.awartha kalaya
2.uparima wi pawathina kalaya

mama hithanne duty cycle eka gana therenna athi...

dam api balamu PWM gana...PWM kiyanne Pulse Width Modulation kiyana ekane...e kiyanne pulse eke(tharangaye) plala wenas kirima kiyala sarala adahasak ganna puluwan....
PWM karanne uC waladi...samahara IC waladi(555 th thiyenawa)
api uC gaa hithamu...ewaye wenamama PWM module thiyenawa...(PIC16F877A data sheet 1 balanna)
ithin api uC eke output ekakin PWM signal 1k gannawa...
uC ekata api kiyanawa menna me duty cycle thiyena PWM out 1k apita one kiyala...ethakota uC eka digatam api illapu tharangaya denawa...
api uC ekata kiyanna ona apita ona Duty cycle 1 kochcharada kiyala
e wagema api e duty cycle 1 ganna ona wave 1 labenna ona sankayathayath kiyanna ona..
apita ethakota out 1k labenawa
me wage .. 75% -duty cycle @ 5kHz

dan balamu Neo kiyala thiyena LED kathawa...
ekedi PWM eka ... 90%-duty cycle @ 5kHz ne
e kiyanne wave eke awartha kalayen 90%kadi tharangaya uparima (max) agayata enawa...10% kadi min agayata enawa
me wave 1 5kHz ne...
e kiyanne awartha kalaya=1/sankayathaya =1/5000=0.0002S = 200uS
dan me 200uS walin 90% k duty ... e kuwe uparimai....
uparima kalay = 200*90/100=180uS
10%k min
awama kalaya=200*10/100=20uS
nathnam,200uS-180uS=20uS

hithanna me welwan wens wima siduwenne 5kHz wegayakin
thapparayakata 5000 wathawak wenawa
ape ahata penne na ne..

e wagema...
me wave 1 LED 1ta dunahama...LED 1 180uS paththu wela thiyenawa...20uS niwila thiyenawa....