voltage divider circuits input transducers input transducers are devices that convert a change in...
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Voltage Divider Circuits
Input transducers1R
2R
0V
V
Input transducers are devices that convert a change in physical conditions (for example, temperature) into a change in resistance and/or voltage. This can then be processed in an electrical network based on a voltage divider circuit.
If two or more resistors are connected in series, the voltage over each resistor will depend on the supply voltage and the ratio of the resistances.
Voltage divider circuits work on the basic electrical principle that if two resistors are connected in series across a supply, the voltage load across each of the resistors will be proportional to the value of the resistors.
Voltage divider circuit
If an input transducer changes its resistance as the physical conditions change, then the resistance change has to be converted into a voltage change so that the signal can be processed. This is normally done using a voltage divider circuit.
0 volts
R
V
2
S
R 1
V
This circuit basically consists of two resistors connected in series. If you change the value of R1 the voltage across it will change as will the voltage across R2. The resistors divide the voltage up between them.
The voltage across R2 is normally called the output or VO. The voltage is divided up according to the formula:
S21
2O V
RRR
V
21
2 s2
RRR
VV
Worked Example: Voltage Divider Circuit
Calculate the voltage signal V2 acrossThe resistor R2 in the voltage divider circuit shown.
0 volts
R2 = 40KV2
Vs = 12 volts
R1 = 80K
400008000040000
12V 2
volts4V2 Using Kirchoff’s second law, we can calculate the voltage over the 80K resistor.
21T VVV 4V12 1
volts8V1
Exercises
0 volts
R2 = 810RV2
VS = 12 volts
R1 = 270R
1.) Calculate the voltage signal V2 across the resistor R2.
21
2 s2
RRR
VV
810270810
12V 2
0.7512V 2
volts9V2
Exercises
0 volts
R2 = 10KV2
VS = 12 volts
R1 = 390R
2.) Calculate the voltage signal V2 across the resistor R2.
21
2 s2
RRR
VV
1000039010000
12V 2
0.9612V 2
volts11.55V 2
Exercises
0 volts
R2 = 47KV2
VS = 6 volts
R1 = 10K
3.) Calculate the voltage signal V2 across the resistor R2.
21
2 s2
RRR
VV
470001000047000
6V 2
0.826V 2
volts4.95V2
Exercises
0 volts
R2 = 2.2KV2
VS = 9 volts
R1 = 10K
4.) Calculate the voltage signal V2 across the resistor R2.
21
2 s2
RRR
VV
2200100002200
9V 2
0.189V 2
volts1.6V2