elec1111 10 opamps2 p
DESCRIPTION
.TRANSCRIPT
1
Electrical Engineering & Telecommunications
Lecturer:Ted Spooner
Op Amps-Other Circuits
Elec1111Elec1111
Rm 124A EE email: [email protected]
Other Applications
• Current to voltage converter.• Full wave rectifier.• Differentiator.• Square wave from Sine.• Triangular wave Oscillator.
2
Current to voltage converter
+
-
Rf
Vo
i
Half wave rectifier
+
-
Rf
R1
Vi Vo
3
Full wave rectifier
+
-
20k
20k
Vi+
-10k
Vo
20k 20k
Differentiator.
+
-
Rf
C
Vi Vo
4
Square wave from Sine.
+
-
Vi Vo
Square wave from Sine…..Better one,
+
-
Rf
R1
ViVo
5
Comparator….over temp alarm
+
-
VoVn
i1
Vsupply
R2
R1
Vp
Vsupply.R2R1+R2
Vo Vn
Vp =
Integrator
∫
∫
−=
−===+
==
=≈
dtRV
CV
RiRiVii
dtiC
VV
fo
o
of
ocap
1
1
10111
1
1
0
10Vp Vn gain high of because Assume
+
-R1
Vi Vo
Vn
Vp
Cf io
i1
6
Triangular wave Oscillator.
+
-
R1
+
-
C1
VoR2
R3 R4
R5
Frequency ....(R3 + R4) and C1Amplitude......Ratio of R5 to (R1 + R2)
Tacho circuit
T1
T2
Fudge factors & assumptions:
Assume T1 constant
Assume T2 >> T1
Assume an equilibrium state has been reached in the output wrt input. ie the voltage at the output is the same at the beginning of one cycle as it was at the beginning of the last cycle.
+
-R1
Vo
Vn
Vp
Cf io
i1
Vp
R2
Rf
7
Tacho circuit
T1
T2
speedTT
RRfV
V
TRfV
CT
RV
C
TRfV
CV
TRV
CV
VdtRV
CV
po
f
p
f
fo
p
fo
p
T p
fo
∝−=
=−
Δ
>>=Δ
=
−=Δ
−=Δ ∫
2
1
1
20
11
2ff20
f
2
11
01
1
11equal are Vs statesteady under If
discharge. RC ofpart linear on still So
T CR assumes This 1R through dischargesCapacitor
0 Vin becausegintegratin stopsoutput T During
1
const is 1down integratesoutput T During
1
+
-R1
Vo
Vn
Vp
Cf io
i1
Vp
R2
Rf
Refs• Op-amp Basics
http://www.national.com/onlineseminar/2003/opamps_basics/090303_Opamp_Trivia_Notes.pdf Nice overview of operation amplifiers from National Semiconductor
• Op-amp Applications Book http://www.analog.com/library/analogDialogue/archives/39-05/op_amp_applications_handbook.html Analog Device's extensive coverage of op-amps and their applications
• The Monolithic Op-amp http://www.national.com/an/AN/AN-4.pdfRobert Widlar's classic app note on op-amps
• Op-amp Applications Guide http://www.national.com/an/AN/AN-20.pdf Op-amp Circuit Collectionhttp://www.national.com/an/AN/AN-31.pdf Extensive collection of applications of op-amps
• Op-amps for Everyone http://focus.ti.com/lit/an/slod006b/slod006b.pdfTexas Instrument's extensive design reference on op-amps
• 555 Timer Tutorial http://www.uoguelph.ca/~antoon/gadgets/555/555.html Fantastic tutorial on the highly versatile and useful 555 timer