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# How do I determined the capacitance that is needed in a circuit?

How do I determine what capacitors do I need in a circuit. For example, to make a LED blink. Thank you for your help.

370Views2Replies

How do I determine what capacitors do I need in a circuit. For example, to make a LED blink. Thank you for your help.

## Discussions

Put some easy values and see if the blink duration is ok

then is the off time acceptable. If not long enough increase R and C..

If the off time is short, increase the value of R1.and C1....

Repeat until satisfied..

A

The most common way to get flashing LEDs is to use a 555 timer. The formulas to calculate the resistors and capacitor needed are on the wikipedia page, and will also be on the datasheets for the 555. There are a number of guides on this site to using the 555 and picking the right component values.