This week Bob shows you the well known utility timer chip, the 555.  He demonstrates both the Monostable and Astable modes as well some additional options.


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Additional Notes

Link to Wikipedia page:

Page includes the graphics used in the show, and a good description of how how the IC can be used.

IC (including supplier) used:

and the datasheet:

Monostable Circuit:

470uF Capacitor with different resistors

A 2.2kΩ resistor, yields a 1 second time.

A 10kΩ resistor, yields a 6 second time.

A 47kΩ resistor, yields a 25 second time.

A 10kΩ pull-up resistor was used on the push button.

Favorite calculator:

AStable Circuit:

On the breadboard, 4.7uF and 100uF capacitors, along with R1 resistors of 470Ω and 4.6kΩ were used.  In all examples, R2 is a 4.6kΩ resistor.

R1        Cap        Freq.        Duty Cycle

4.6kΩ        4.7uF        22Hz        66%

4.6kΩ        100uF        1Hz        66%

470Ω        4.7uF        32Hz        52%

470Ω        100uF        1.5Hz        52%

Favorite calculator: