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.

Downloads

HD Apple HD Apple SD Audio MP3

Additional Notes

Link to Wikipedia page:http://en.wikipedia.org/wiki/555_timer_IC

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

IC (including supplier) used:  http://www.mouser.com/Search/ProductDetail.aspx?qs=gb35HGp1gQKvnuQa7j7RAQ==

and the datasheet:  http://www.ti.com/lit/ds/slfs022h/slfs022h.pdf

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:  http://clarkson-uk.com/555-timer/operation/frames2.html

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:  http://www.ohmslawcalculator.com/555_astable.php