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
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