Music Synthesis Using the 555 Timer
Music Synthesis Using the 555 Timer
Chris Whiting & Keddy Malcolm1Overview555 Timer Pin
Layout555 Timer Configuration 555 Timer Other ApplicationsMalcolm
ResultsWhiting ResultsConclusionSources
555 Timer Pin Layout
2TRIGOUT rises, and interval starts, when this input falls below
1/3VCC.6THRThe interval ends when the voltage at THR is greater
than at 2/3 Vcc.4RESETA 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. 5CTRL"Control" access to the
internal voltage divider (by default, 2/3VCC). 7DISOpen collector
output; may discharge a capacitor between intervals. In phase with
output.3OUTThis output is driven to approximately 1.7V below +Vcc
or GND.555 Timer Pin DescriptionsSquare wave output, how?Capacitor
Charge Time: T1 = 0.693(R1+R2)C1Capacitor Discharge Time: T2 =
0.693(R2)C1The output frequency is determined by the following
equation:
Simple astable configuration
555 Timer Pin Descriptions Duty Cycle of waveform Pulse
Width/PeriodThe Duty cycle is determined by the following
equation:
Duty Cycle Relationship to output frequency Large R2 wrt
R1Control capacitor reduces noise
555 Timer - Other ApplicationsTwo modes of operation:Monostable
Mode Output Single PulseAstable Mode Output Continuous
PulsesBistable Mode Output acts as Basic Flip-FlopLinear RampPulse
Width ModulatorFrequency Divider555 Timer - Other
ApplicationsLinear Ramp
555 Timer - Other ApplicationsPulse Width Modulator
555 Timer - Other ApplicationsFrequency Divider
Malcolm-Design Overview Week 1
Switch PlacementDesign Overview Week 2
11Assembly ProblemsWeek One:Change resistors to get frequencies
correctMistakes in wiringWeek Two:Problems with wiringBalance
between volume and waveform outputComponent Precision
Malcolm Results Week 1
Waveform Results: 259 Hz
Rise time: 1.86 msFall time: 1.76 msDuty Cycle: 51.38%
Waveform Results: 293 Hz
High Time: 1.64msLow Time : 1.66msDuty Cycle: 49.7%Waveform
Results: 329 Hz
High Time: 1.42ms Low Time: 1.42msDuty Cycle: 50%Waveform
Results: 349 Hz
High Time: 1.41msLow Time: 1.41msDuty Cycle: 50%Waveform
Results: 391 Hz
High Time: 1.27msLow Time: 1.28msDuty Cycle: 49.80%
Waveform Results: 440 Hz
High Time 1.14msLow Time 1.12msDuty Cycle: 50.80%Waveform
Results: 493 Hz
High Time: 1.02ms Low Time: 1.01msDuty Cycle: 50.44%
Waveform Results: 523 Hz
High Time: 968us Low time: 948 usDuty Cycle: 50.25%
Malcolm Results Week Two
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 ResultsFrequencies and duty cycle very accurate in first
stageFrequencies loose accuracy in the second stageExcellent sine
wave poor volume qualityChris Final Circuit DiagramUsed
potentiometers in the lab to more accurately obtain desired output
frequencies
Chris 555 Timer CircuitR2 value determines output frequency.Duty
Cycle unaffected because R2 >> R1Various 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 WaveA
square wave is the sum of multiple sine waves at odd multiples of
the square waves 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 WaveTheoretical & Experimental results
for 555 timer circuit square wave output
Chris Results Square WaveDifferent resistances attributed
to:Potentiometers, inaccurate capacitors, 555 timer
18.52% Difference?!Chris's Results Sine WaveTheoretical &
Experimental results for 555 timer and filter combination sine wave
output
Chris's Results Sine WaveDifferent resistances attributed
to:Potentiometers, inaccurate capacitors, 555 timer
20.08% Difference?!Chris's Results Sine WaveSquare wave to Sine
Wave conversionDuty Cycle = 50.0% 0.2% error on average
Chris's Results Sine WaveSquare wave to Sine Wave conversionDuty
Cycle = 50.0% 0.2% error on average
524.091Hz523.063HzConclusion555 Timer Pin Layout555 Timer
Configuration 555 Timer Other ApplicationsMalcolm ResultsWhiting
Results
Sourceshttp://blog.makezine.com/2008/01/29/how-to-guitar-hero-autowh/http://www.ecelab.com/circuit-astable-555.htmhttp://www.cc.gatech.edu/classes/AY2011/cs3651_spring/docs/LM555.pdfhttp://home.cogeco.ca/~rpaisley4/LM555.html
Questions?Sheet1TheoryActualHigh TimeLow TimeDuty
CycleRBRA261.625260.71.86ms1.76ms51.38%26.7k.995k293.664290.71.64ms1.66ms49.70%23.9k329.6273351.42ms1.42ms50.00%20.49k349.228351.21.41ms1.41ms50.00%19.6k391.995390.61.27ms1.28ms49.80%17.6k4404311.14ms1.12ms50.44%15.9k493.8834941.02ms1.01ms50.25%13.8k523.251530.8968us948us50.52%12.86k
Sheet1TheoryCalculatedfrequencycurrent261.625264Hz270.54Hz16.7mA293.664295Hz303.55
Hz17.3mA329.627343Hz354.93 Hz17.4mA349.228358Hz372.66
Hz17.5mA391.995397Hz416.67 Hz17.6mA440439Hz462.01
Hz17.9mA493.883503Hz528.73 Hz18mA523.251539Hz580.81 Hz18.2mA
