led dimmer with ka3844

[nhghost]

led dimmer with uc3844

led dimmer from 220V, 50hz.
I can do with 555 but can't with ka3844 (or uc3844 or uc3842)
I don't know how to control duty cycle (Ratio) with ka3844...help..........

 

[KJ6EAD]

Try varying the current on pin 3 as shown in the test circuit. https://www.fairchildsemi.com/ds/KA/KA3844B.pdf

 

[nhghost]

Try varying the current on pin 3 as shown in the test circuit.

omg. thank you very much.
before your reply, I tried test circuit. but it not work (
after your reply, I try again. remove pin 1 and pin 2 --> work
Now I can control duty cycle :idea:

thank you very much!!!!!!!!!!!!!!!!!!!!!!

---------- Post added at 11:31 ---------- Previous post was at 11:21 ----------

not enough post, can't add image. Now enough
Why I use uc3842, it work but when use uc3844, haven't signal output

the circuit I remove pin1, pin 2
when V pin3>xxx --> output=0


ps: I speak English very bad . thank for read my thread :-?