I was working for a line follower ,i did'nt get infrared proximitysensors in our local market. So i hav to assemble it with TSOP sensors(which are available every where as they are used in electronic appliances like TV,CD player). I have to assemble a 38KHz pulse generator with 50% duty cycle. I tried it with 555 timer IC . I used it according to datasheets but that doesn't work.....I have used the general circuit with Ra=4.7K ohms , Rb=13.7K ohms and C=1nF ,but that does not give 38KHz from calculations.
Here is the formula for 555 Timer in astable mode
f=1.44/(Ra+2*Rb)C
