555-based variable frequency square-wave oscillator

audioguru said:

Hi Indecided,
How's your shift-light circuit? Have you ignored it and over-rev'd your engine yet? :lol:

Your 555 circuit has way too much range. It will go from about 200Hz all the way to about 100KHz. Its pot will be so sensitive that it will be impossible to set a frequency.
Sorry, I can't remember what range you need. Do you have a 18,000 RPM formula-1 engine or a little putt-putt?
First of all increase the value of the 1K resistor. It mainly sets the highest frequency.
Secondly, add power supply bypassing right at the IC, like most ICs need.
Lastly, add a 100 ohm or 1K resistor in series with its output, since a 555 is powerful enough to destroy itself and a lower-voltage load.

I pasted together parts of its datasheet for you:

Click to expand...