I’m new to electrical engineering and this is my first time working with an oscillator. I'm trying to setup a 555 timer ic as an oscillator with a low time of 1s and a high time of 0.5s. I've been using the following wire diagram, with the exception I am currently not using D2, though the results are the same with it as without it.
I'm using the following: C1 = 10uf R1 = 150kohm R2 = 75kohm A TLC555CP IC.
Every thing works except the LOW and HIGH times are the reverse of what I had expected from all the reading I have done. I got a result of 1s on and 0.5s off. If I reversed R1 and R2 then I got what I wanted 1s off and 0.5s on.
This seems counter to everything I've read that said R2 had to be less than R1 to get a less than 50% duty cycle. If anyone can tell me why this is I would be most appreciated.
I’ve also noticed that when power is first applied to the ic I get an instant ON that is longer than desired. All successive ON cycles are okay. Any suggestions for dealing with this are much appreciated.