Adjusting LM555 timer frequency

[bob987]

I found the following circuit http://www.555-timer-circuits.com/bi-polar-led-driver.html that suits the task I am trying to achieve. My only issue is I don't know what the frequency would be or how to change it. Is the frequency determined by the cpacitor and the 33K resistor or is it more complex. Any help would be appreciated. Thanks for your time.

 

[schip666!]

Yes the 33K resistor and 10uF capacitor set the flash rate. Increasing either will slow the flashes.

Find a 555 spec sheet or application note online. They usually have an extensive section about calculating the timing, and some convenient graphs that will get you into the ball-park.

Also look at this forum and find the other folks who are trying to make led flashers and send them that schematic...I've reached my 555 answer limit for the week...