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