555 Timer Calculator

ezdays

Out AZ way
Caclulating the components of a 555 can be tricky at times, especially if you're looking for accurate long time delays, so this site is great.

Speaking of long time delays, one word here. I've used the 555 for timers in the range of minutes, and found that you cannot use large value (10 mfd or greater) cheap capacitors for that purpose. Cheaper, "filter" capacitors have too much leakage (a low resistance factor) making it impossible to achive that kind of delays. Use a tantilum, or other low leakage capacitors and that takes care of the problem.

Just another piece of usless information, until you need it....
 
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