THE FACEMELTER3000™

JOE GROELE

Project Outline

The goal of this project was to build a plasma speaker that will amplify an electric guitar sound.

Build an audio oscillator circuit using an ordinary speaker

Test speaker performance compared to equations on data sheet

Replace speaker with auto ignition coil to create a plasma arc

Replace audio oscillator with an Audio Power Amplifier

Hypothesis

I hypothesize that an Audio Power Amplifier will be capable of magnifying the output of an electric guitar through a plasma arc.

The values of the measured frequency and duty cycle will match the equations on the data sheet for the oscillator circuit if built correctly.

Materials Solder Soldering iron Wire Wire strippers Wire Cutters Multimeter Oscilloscope Electronic tuner Perf board Auto spark ignition Connector terminal Power connector Guitar input jack

Eight pin DIP socket 0.01 µF capacitor 0.1 µF capacitor 10 ohm resistor 330 ohm resistor 100 ohm resistor 1 K ohm resistor 10 K ohm potentiometer IRF510 MOSFET transistor P2N2222 transistor ICM7555 CMOS timer LM386 audio power

amplifier

Constructing the Audio Oscillator Circuit Create the audio oscillator using the ICM7555

CMOS timer following the product data sheet Add amplifying transistors from example circuit

Example circuit from: http://geocities.com/CapeCanaveral/Lab/5322/fbt2.htm

Audio Oscillator Circuit Diagram

10KPOT1

10KPOT1

100

RESISTOR

1

IC M 75 55 10

RESISTOR

1KRESISTOR

330RESISTOR

1KRESISTOR

2N2222

NPN

IRF510

NMOS

SPEAKER

0.1 or 0.01C

GND

6

3

2

7 8 4

9V

Testing the Audio Oscillator Circuit Connect speaker to the output Attach a 9 Volt battery Frequency and duty cycle are changed by

adjusting the two potentiometers and the value of the capacitor

Take measurements of frequency and duty cycle using an oscilloscope and an electronic tuner

Compare to calculated values

Frequency and Duty Cycle Connect oscilloscope

and take measurements, T1 and T2

Use ohm meter to measure RA and RB

Adjust potentiometers and repeat measurements

T1

T2

Measured: Calculated:

CRRF

BA )2(

38.1

2

1

TF

2

1

T

TD

BA

BA

RR

RRD

2

Creating a Plasma Speaker Replace speaker with auto ignition coil Connect wires from the primary coil to the circuit board Attach wires to the secondary high voltage coil Adjust spacing between wires to create a small gap - 2

to 5mm worked best When the circuit is energized, the air between the

electrodes is ionized and becomes a plasma A new spark is created with every oscillation of the circuit Your ear hears this as a musical tone The frequency or note of the tone can be adjusted using

the potentiometers

Creating the Plasma Powered Guitar Amp A second copy of the circuit was constructed, replacing the

oscillator chip with a low voltage audio power amplifier The gain of the amplifier was increased to 200, which

gives a square shaped wave form The spark also produces a sound, but now the frequency

corresponds to the note being played on the guitar

C6 = 1046.5 Hz C5 = 523.25 Hz

Audio Oscillator Diagram – With Coil

1

10KPOT1

IC M 75 55

10KPOT1

100

RESISTOR10

RESISTOR

1KRESISTOR

330RESISTOR

1KRESISTOR

2N2222

NPN

IRF510

NMOS

0.1 or 0.01C

GND

Auto Ignition CoilT

6

3

2

7 8 4

9V

RA

RB

12 V

100

RESISTOR10

RESISTOR

330RESISTOR

2N2222

NPN

IRF510

NMOS

GND

Auto Ignition CoilT

tip

J?

PHONEJ

1

-2

+3

5

8

6

7

4

LM386

10uF

C

10, 450VC

..

G?GND

The FaceMelter3000™

Data and CalculationsRA,k ohms RB, k ohms C, nF T1, div T2, div

Scale, seconds/div

Calculated Frequency, Hz

Calculated Duty Cycle, %

Measured Frequency, Hz

Measured Duty Cycle, % Note

1 11.52 11.19 116.7 3.3 5.1 0.0005 348.8 66.99% 392.2 64.71%2 8.41 11.19 116.7 2.9 4.7 0.0005 384.1 63.66% 425.5 61.70%3 4.12 11.19 116.7 2.2 4 0.0005 446.2 57.77% 500.0 55.00%4 1.003 11.19 116.7 4.3 9 0.0002 505.7 52.14% 555.6 47.78%5 11.52 7.62 116.7 7 10 0.0002 441.9 71.52% 500.0 70.00%6 7.86 7.62 116.7 5.5 8.6 0.0002 511.9 67.01% 581.4 63.95%7 4.88 7.62 116.7 4.5 7.6 0.0002 587.7 62.13% 657.9 59.21%8 1.003 7.62 116.7 3 6.1 0.0002 728.0 53.09% 819.7 49.18%9 11.52 4.39 116.7 5.8 7.5 0.0002 582.5 78.37% 666.7 77.33%

10 8.35 4.39 116.7 4.5 6.2 0.0002 690.3 74.37% 806.5 72.58%11 4.4 4.39 116.7 6.2 9.8 0.0001 897.2 66.69% 1020.4 63.27%12 1.003 4.39 116.7 3.9 7.3 0.0001 1208.7 55.13% 1369.9 53.42%13 11.52 1.003 116.7 9 9.8 0.0001 874.3 92.58% 1020.4 91.84%14 7.44 1.003 116.7 6 6.9 0.0001 1251.9 89.38% 1449.3 86.96%15 4.19 1.003 116.7 7.2 8.9 0.00005 1908.5 83.81% 2247.2 80.90%16 1.003 1.003 116.7 2.9 4.4 0.00005 3929.9 66.67% 4545.5 65.91%

1 11.51 11.18 13.16 4.4 6.9 0.00005 3096.1 66.99% 2898.6 63.77%2 8.87 11.18 13.16 3.9 6.1 0.00005 3357.8 64.20% 3278.7 63.93%3 4.48 11.18 13.16 3 5.3 0.00005 3907.0 58.35% 3773.6 56.60%4 1.003 11.18 13.16 2.2 4.7 0.00005 4488.4 52.15% 4255.3 46.81%5 11.52 7.58 13.16 3.7 5.2 0.00005 3930.4 71.59% 3846.2 71.15%6 7.88 7.58 13.16 3 4.7 0.00005 4551.4 67.10% 4255.3 63.83%7 5.08 7.58 13.16 6 10 0.00002 5181.0 62.55% 5000.0 60.00%8 1.004 7.58 13.16 4 8.1 0.00002 6487.5 53.11% 6172.8 49.38%9 11.51 3.79 13.16 7.2 9.2 0.00002 5493.1 80.15% 5434.8 78.26%

10 7.87 3.79 13.16 5.6 7.5 0.00002 6787.3 75.47% 6666.7 74.67%11 4.55 3.79 13.16 4 6 0.00002 8644.9 68.76% 8333.3 66.67%12 1.003 3.79 13.16 2.2 4.3 0.00002 12217.5 55.84% 11627.9 51.16%13 11.51 1.004 13.16 6 6.7 0.00002 7757.3 92.57% 7462.7 89.55%14 8.08 1.004 13.16 8.8 9.8 0.00001 10394.8 90.05% 10204.1 89.80%15 4.25 1.004 13.16 5 6.1 0.00001 16756.7 83.96% 16393.4 81.97%16 1.003 1.004 13.16 4 6.1 0.000005 34826.7 66.66% 32786.9 65.57%17 11.49 10.53 116.7 3.7 5.9 0.0005 363.3 67.65% 339.0 62.71% F418 6.42 6.14 116.7 5.2 8.3 0.0002 632.4 67.17% 602.4 62.65% D#519 3.28 2.16 116.7 4.3 6.7 0.0001 1555.9 71.58% 1492.5 64.18% G620 2.557 2.047 116.7 3.9 5.9 0.0001 1778.0 69.22% 1694.9 66.10% A621 1.113 1.014 116.7 3.4 5.5 0.00005 3764.8 67.72% 3636.4 61.82% A#722 9.08 9.68 950.4 3.1 5.2 0.005 51.1 65.96% 38.5 59.62% D#123 7.87 7.86 950.4 2.7 4.3 0.005 61.6 66.68% 46.5 62.79% F#124 1.465 3.96 950.4 4.3 8.2 0.001 154.7 57.81% 122.0 52.44% B225 1.807 2.87 950.4 3.8 6.7 0.001 192.4 61.97% 149.3 56.72% D#3

0.0 5000.0 10000.0 15000.0 20000.0 25000.0 30000.0 35000.0 40000.00.0

5000.0

10000.0

15000.0

20000.0

25000.0

30000.0

35000.0

40000.0

Comparison of Measured and Calculated Frequency

Calculated Frequency, Hz

Mea

sure

d F

req

uen

cy,

Hz

0.0 500.0 1000.0 1500.0 2000.0 2500.0 3000.0 3500.0 4000.00.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

F4

D#5

G6

A6

A#7

D#1

F#1B2

D#3

Comparison of Measured and Calculated Frequency

Calculated Frequency, Hz

Mea

sure

d F

req

uen

cy,

Hz

Scale notes' frequencies measured using an elec-

tric tuner.

50.00% 55.00% 60.00% 65.00% 70.00% 75.00% 80.00% 85.00% 90.00% 95.00%40.00%

50.00%

60.00%

70.00%

80.00%

90.00%

Comparison of Measured and Calculated Duty Cycles

Calculated Duty Cycle, %

Mea

sure

d D

uty

Cyc

le,

%

Conclusions Measured values of frequency and duty cycle

were only two significant figures, resulting in less accuracy

The electronic tuner was more accurate than the oscilloscope because the tuner, like an ear, can hear smaller differences in frequency – verified by comparing the pitch to a piano

The plasma guitar amplifier produced a satisfactory sound, but the volume and sustain could be dramatically improved