1. CU ATLAS Practical electronics Making NOISE with the 555 TIMER
Wayne Seltzer – Feb 27, 2016

2. Learning Objectives How can we create signals?
Understand the Resistor/Capacitor (RC) circuit
Build a tone generator with a 555 timer
Optional: Solder the circuit on a perfboard

3. How can we create signals?
Signal = value that changes over time
What are other examples of signals?

4. Resistor/Capacitor (RC) Circuit
Source:
Vc is the voltage across the capacitor
Vs is the supply voltage
t is the elapsed time since the application of the supply voltage
RC is the time constant of the RC charging circuit

5. Neon bulb RC blinker (oscillator)
110 volts AC

6. 555 timer astable oscillator
+ 5 volts
102 = 10 x 102 =1K
103 = 10 x 103 =10K
1K
10K
220
optional LED

7. Discussion Topics
Change the capacitor and/or resistor values to change the frequency and duty cycle
Construct the 555 circuit by soldering the components on a perfboard
Build a tone generator using an Arduino. What are the advantages/disadvantages vs. the 555 timer circuit?