2 - DC RC Networks

2016-05-08 21:31:00 +0000, 2 years and 3 months ago

2.01 - timing circuits

Resistor capacitor circuits are useful for timing circuits because the capacitor and resistor can be used like a voltage divider, when there is no voltage into the circuit, the capacitor discharges through the resistor for a set amount of time; depending on the R and C values. This is shown below:

  +-----+Vs---------+
  |                 |
1 V    +-----+  C+  |
  --*--+     +--||--+
2 ^ S  +-----+      |
  |                 |
  +-----Vout--------+

When the switch, S, is closed to contact 1, the current flows through the resistor and into the capacitor, charging it. When the switch is closed onto contact 2, the capacitor then discharges through the resistor over a certain time.

Time constants are used in resistor capacitor circuits as a way to measure dis/charging over time.

                  __________
 +Vs |````````````_.--------- never equal 
     |``````````.' :    :   : to +Vs
     |....... /`   :    :   :
     |      ,` :   :    :   :
0.63 |...../   :   :    :   :
 +Vs |   /`:   :   :    :   :
     |  /  :   :   :    :   :
     | /   :   :   :    :   :
     |/    :   :   :    :   : 
     +-----------------------
     0    1RC 2RC 3RC 4RC  5C
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