This calculator evaluates the performance of the generic bipolar 555 timer chip in both monostable and astable modes. Please enter the component values you require in the spaces provided, then click on the button and the results will be displayed.
As a rule of thumb, it is best to choose resistor values above 1K and below 1Meg. Large electrolytics should be avoided in favour of large value R's to reduce power consumption and timing inaccuracies due to leakage.
*I will of course remove this material at Mr Davis' request.