Fill in one of the values below and press ‘go’ and the calculator will give you a range of options for R12 & C1.
|How often do you want the timer to fire?||seconds|
|What frequency do you want the timer to fire at?||Hertz|
About the calculator
There are other calculators on the web, but they tend to approach it from the opposite direction — given R1, R2, and C1, what timing will result? But of course that’s not what you are usually looking for. You have a timing in mind, and you want to know what parts to use to achieve that. Your problems are solved! Just plug the timing you are looking to get into the form below, hit the appropriate ‘Go’ button, and you’ll get a list of possible components options.
For the components, I chose those that come with the Radio Shack ‘grab bags’ of resistors (part #271-003) and capacitors (part #272-801 & 272-802). There are, of course, a lot more possibilities than these, but for most hobbyists there’s a decent chance these will be kicking around.
Update 1 – Mar 13, 2013 – I have added the ability to use SI units, so you can specify “10ms” or “4.5KHz” in the text fields.