music synthesis using the 555 timer
DESCRIPTION
Chris Whiting & Keddy Malcolm. Music Synthesis Using the 555 Timer. Overview. 555 Timer Pin Layout 555 Timer Configuration 555 Timer – Other Applications Malcolm Results Whiting Results Conclusion Sources. 555 Timer Pin Layout. 555 Timer Pin Descriptions. - PowerPoint PPT PresentationTRANSCRIPT
Music Synthesis Using the 555 Timer
Chris Whiting & Keddy Malcolm
Overview
555 Timer Pin Layout 555 Timer Configuration 555 Timer – Other Applications Malcolm Results Whiting Results Conclusion Sources
555 Timer Pin Layout
2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.
6 THR The interval ends when the voltage at THR is greater than at 2/3 Vcc.
4 RESETA timing interval may be reset by driving this input to GND, but the timing does not begin again until RESET rises above approximately 0.7 volts.
5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).
7 DISOpen collector output; may discharge a capacitor between intervals. In phase with output.
3 OUT This output is driven to approximately 1.7V below +Vcc or GND.
555 Timer Pin Descriptions
Square wave output, how?• Capacitor Charge Time: T1 = 0.693(R1+R2)C1• Capacitor Discharge Time: T2 = 0.693(R2)C1 The output frequency is determined by the following
equation:
Simple astable configuration
555 Timer Pin Descriptions
Duty Cycle of waveform – Pulse Width/Period The Duty cycle is determined by the following equation:
Duty Cycle Relationship to output frequency Large R2 wrt R1 Control capacitor reduces noise
555 Timer - Other Applications
Two modes of operation: Monostable Mode – Output Single Pulse Astable Mode – Output Continuous Pulses Bistable Mode – Output acts as Basic Flip-Flop
Linear Ramp Pulse Width Modulator Frequency Divider
555 Timer - Other Applications
Linear Ramp
555 Timer - Other Applications
Pulse Width Modulator
555 Timer - Other Applications
Frequency Divider
Malcolm-Design Overview Week 1
Switch Placement
Design Overview Week 2
Assembly Problems
Week One:• Change resistors to get frequencies correct• Mistakes in wiring
Week Two:• Problems with wiring• Balance between volume and waveform output• Component Precision
Malcolm Results Week 1
Theory Actual High Time Low Time Duty Cycle RB RA261.625 260.7 1.86ms 1.76ms 51.38% 26.7k .995k293.664 290.7 1.64ms 1.66ms 49.70% 23.9k329.627 335 1.42ms 1.42ms 50.00% 20.49k349.228 351.2 1.41ms 1.41ms 50.00% 19.6k391.995 390.6 1.27ms 1.28ms 49.80% 17.6k
440 431 1.14ms 1.12ms 50.44% 15.9k493.883 494 1.02ms 1.01ms 50.25% 13.8k523.251 530.8 968us 948us 50.52% 12.86k
Waveform Results: 259 Hz
• Rise time: 1.86 ms• Fall time: 1.76 ms• Duty Cycle: 51.38%
Waveform Results: 293 Hz
• High Time: 1.64ms• Low Time : 1.66ms• Duty Cycle: 49.7%
Waveform Results: 329 Hz
• High Time: 1.42ms • Low Time: 1.42ms• Duty Cycle: 50%
Waveform Results: 349 Hz
• High Time: 1.41ms• Low Time: 1.41ms• Duty Cycle: 50%
Waveform Results: 391 Hz
• High Time: 1.27ms• Low Time: 1.28ms• Duty Cycle: 49.80%
Waveform Results: 440 Hz
• High Time 1.14ms• Low Time 1.12ms• Duty Cycle: 50.80%
Waveform Results: 493 Hz
• High Time: 1.02ms • Low Time: 1.01ms• Duty Cycle: 50.44%
Waveform Results: 523 Hz
• High Time: 968us • Low time: 948 us• Duty Cycle: 50.25%
Malcolm Results Week Two
Theory Calculated frequency current261.625 264Hz 270.54Hz 16.7mA293.664 295Hz 303.55 Hz 17.3mA329.627 343Hz 354.93 Hz 17.4mA349.228 358Hz 372.66 Hz 17.5mA391.995 397Hz 416.67 Hz 17.6mA
440 439Hz 462.01 Hz 17.9mA493.883 503Hz 528.73 Hz 18mA523.251 539Hz 580.81 Hz 18.2mA
Waveform Results: 261 Hz
Waveform Results: 293 Hz
Waveform Results: 329 Hz
Waveform Results: 349 Hz
Waveform Results: 391 Hz
Waveform Results: 440 Hz
Waveform Results: 493 Hz
Waveform Results: 523 Hz
Overall Results
Frequencies and duty cycle very accurate in first stage
Frequencies loose accuracy in the second stage
Excellent sine wave poor volume quality
Chris’ Final Circuit Diagram
Used potentiometers in the lab to more accurately obtain desired output frequencies
Chris’ 555 Timer Circuit
R2 value determines output frequency. Duty Cycle unaffected because R2 >> R1 Various switches with potentiometers are used to act as
selectors for the output frequency by turning each switch on or off.
Chris’ Filter Circuit
555 Timer Square Wave Output Sine Wave A square wave is the sum of multiple sine waves at odd
multiples of the square wave’s frequency (odd order harmonics)
Chris’ Filter Circuit
Extract the fundamental frequency of the square wave by filtering the higher order sine waves.
Low-pass filter with 600 Hz cutoff frequency and an inverting op-amp connected in series.
Chris’ Results – Square Wave
Theoretical & Experimental results for 555 timer circuit square wave output
Chris’ Results – Square Wave
Different resistances attributed to: Potentiometers, inaccurate capacitors, 555 timer
18.52% Difference?!
Chris's Results – Sine Wave
Theoretical & Experimental results for 555 timer and filter combination sine wave output
Chris's Results – Sine Wave
Different resistances attributed to: Potentiometers, inaccurate capacitors, 555 timer
20.08% Difference?!
Chris's Results – Sine Wave
Square wave to Sine Wave conversion Duty Cycle = 50.0% 0.2% error on average
Chris's Results – Sine Wave
Square wave to Sine Wave conversion Duty Cycle = 50.0% 0.2% error on average
524.091Hz 523.063Hz
Conclusion
555 Timer Pin Layout 555 Timer Configuration 555 Timer – Other Applications Malcolm Results Whiting Results
Sources
http://blog.makezine.com/2008/01/29/how-to-guitar-hero-autowh/
http://www.ecelab.com/circuit-astable-555.htm
http://www.cc.gatech.edu/classes/AY2011/cs3651_spring/docs/LM555.pdf
http://home.cogeco.ca/~rpaisley4/LM555.html
Questions?