frequency changer

[cool-agent]

i am using 555 timer to generate frequency thought i dont know how to change or control frequency though i could use variable resitser but i think that too big, so I also dont know how to increase the cycle/s frequency or does it matter cauz i want at leat 30khz of ultra sonic sound.

 

[stevez]

Sometimes the datasheets for devices contain applications information that can be of great help. Look at National's sheet for an LM555 to see if that helps.