Gabriel FerratéRenzo AlvarezAlyssa BerdingJoe BeanJake Kane
Published © CC BY-ND

The Ohminator Analog Synthesizer

Our project is an all-analog keyboard synthesizer like the ones popular in the 1970s.

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The Ohminator Analog Synthesizer

Things used in this project

Hardware components

Texas Instruments SN74HC04
The HEX inverters where used for controlling the temperature sensor
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555 or 556 Timer (generic)
555 or 556 Timer (generic)
The NE555 Timer is the main component controlling the timing of the Attack-Decay-Sustain-Release (ADSR) envelope generator.
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Texas Instruments SN74HC00
The SN74HC00 Quad, 2-Input, Positive NAND-Gate was utilized to create a 114us negative pulse.
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Analog Devices AD633ARZ-R7
The AD633 Analog Multiplier is used to mix the ADSR envelope generated by the 555 timer based envelope generator and an incoming square/triangle wave generated by a Voltage Controlled Oscillator
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General Purpose Quad Op-Amp
Texas Instruments General Purpose Quad Op-Amp
The LMV324 quad op-amps were used for the heart of the synthesizer: the voltage controlled oscillator.
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Texas Instruments CD4504BPW
The CD4504 Level Shifter was utilized to convert a 5V signal to 15V. The main function was to shift the 5V output of the pulse generator into a 15V level pulse while also shifting 5V to 15V for use in the ADSR envelope generator.
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Texas Instruments NE5532
The NE5532 Dual-Channel Operational Amplifier was used for a variety of of different function. It was used as a buffer, attenuator, inverter, summer, and many other applicataions.
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Maxim Integrated MAX9744
The MAX9744 was the power amplifier used as the final amplifier to amplify the final signal to appropriate levels for the output speakers.
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SparkFun COM09340 - White Concave Button
The white button is used as part of the keyboard and is colored white to emulate piano keys
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SparkFun COM09339 - Black Concave Button
The black button is used as part of the keyboard and is colored black to emulate piano keys.
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Texas Instruments PTN78000
The PTN78000 switching regulator is used to generate required power rails to power our systems
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Texas Instruments LM35 - Temperature Sensor
The LM35 Temperature Sensor was utilized to monitor the temperature of the 20W Maxim power amp and to control a cooling fan if it reaches a certain temperatures.
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Quad Comparator
Texas Instruments Quad Comparator
The LM239 Comparator is used to identify when a key is being pressed during operation. It also triggers the 555 timer in the ADSR envelope to trigger and begin generating the envelope.
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Hand tools and fabrication machines

Laser cutter (generic)
Laser cutter (generic)
The laser cutter was used for cutting the top and bottom part of the enclosure
3D Printer (generic)
3D Printer (generic)
The 3D printer was used for making the lateral parts of the enclosure

Story

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Custom parts and enclosures

3D enclosure

This is the 3D model for the enclosure for the synthesizer.

Schematics

Circuit diagram

This is the circuit diagram of the synthesizer in eagle

Board layout

This is the board layout for the PCB of the synth in eagle

Code

BenchVue Test

Scratch
We used the BenchVue software for testing our tuning.
No preview (download only).

Credits

Gabriel Ferraté

Gabriel Ferraté

1 project • 0 followers
Renzo Alvarez

Renzo Alvarez

1 project • 0 followers
Alyssa Berding

Alyssa Berding

1 project • 0 followers
Joe Bean

Joe Bean

1 project • 0 followers
Jake Kane

Jake Kane

1 project • 0 followers

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