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Operational Amplifier555 Timers
Term 4 Projects
Operational Amplifier
An Op Amp is made of:
1) Gain "Block"
2) Feedback
3) A Network
Gain "Block"
+
-
Feedback+
-
Network+
-
R2
R1
Gain
G =R2
R1
“Stair-stepping” Gain
555 TimerTiming CircuitOscillatorControllable
8 Pin DIP
DIP – Dual Inline Package
Pin
555 Timer Pins
Gnd
Trigger
Output
Reset
Vcc
Discharge
ThresholdControlVoltage
12
3
4
87
6
5
Typical Wiring
T2=0.693(Rb)C(Disharge)
T1=0.693(Ra+Rb)C(Charge)
T1
T2
Pin 3Output
FrequencyCycles per SecondHertz - HzF = 1/T555 Timer
F = 1/(T1 + T2)
Example Ra = 6.8KΩRb = 6.8KΩ
C = 0.15µf
T1=0.693(6.8kΩ+6.800k) 0.15μf
T1= 1.41ms
T2=0.707 ms
T2=0.693(6.8kΩ) 0.15μf
F = 1/(T1+ T2)F = 1/(1.41 ms + 0.707 ms)
F = 1/(0.00141s + 0.000707s)
F = 472Hz
T1=0.693(6800Ω+6800Ω) 0.00000015f
T2=0.693(6800Ω) 0.00000015f
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