View source for Analog Modular Synthesizer (Project 0024)

<small>by Daria Palenova</small>
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{{DISPLAYTITLE:Analog Modular Synthesizer}}
[[Category:Projects|Analog Modular Synthesizer]]

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== Project Overview ==

Modular synthesizers are synthesizers composed of separate modules for different functions. The modules can be connected together by the user to create a patch. The outputs from the modules may include audio signals, analog control voltages, or digital signals for logic or timing conditions. Typical modules are voltage-controlled oscillators, voltage-controlled filters, voltage-controlled amplifiers and envelope generators.

{{#widget:gallery|img1=https://drive.google.com/uc?export=view&id=1mf1e1B_qMe1jPg_-w0lMjn2SpJocWQPF|img2=null|img3=null|img4=null|img5=null|num=2}}

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== Tools and Materials ==
* Power supply
* Oscilloscope
* Bread boards/ PCB protoboards & soldering iron
* 
* VCO (function generator):
* ICL8038
* 0.1 uF capacitor
* 0.0047 uF capacitor
* Si diode
* 1K potentiometer
* 10K potentiometer
* 2*4.7K resistors
* 15K resistor
* 20K resistor
* 
* Audio Amplifier:
* LM386
* 2*10K potentiometer
* 10 kOhm resistor
* 10 Ohm resistor
* 1000 uF capacitor
* 100 uF capacitor
* 2*10 uF capacitor
* 3*0.1 uF capacitor
* 470 pF capacitor
* 1 speaker
* 
* Filters:
* resistors, capacitors, and op-amps depending on your design.
* here are mine:
* 
* Low pass:
* 2*100kOhm resistors
* 882kOhm resistor
* 2*1.6 nF capacitors
* 160 pF capacitor
* 2*TL082 op-amp
* 
* High pass:
* 5*1.1nF capacitors
* 96.5kOhm resistor
* 30kOhm resistor
* 312 kOhm resistor
* 119kOhm resistor
* 78.1kOhm resistor
* 
* 
* Optional: banana receptacles and cables
* 


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== Project Files==
* [https://drive.google.com/open?id=1zGf7JezG8EaJf5kCu6oiAC_V0XVn8ce6 Modular Synthesizer presentation - Dasha Palenova.pdf]
* [https://drive.google.com/open?id=1pAc4jt_iPHYiTHLvudQiRKS13Rmfiu-h Modular_Synth_highpass_schematic - Dasha Palenova.JPG]
* [https://drive.google.com/open?id=1y62XP1QhTwKy3AwBLAMVbUg07Bk4XiWp Modular_Synth_lowpass_schematic - Dasha Palenova.JPG]
* [https://drive.google.com/open?id=1HCxzQ9JK1abBDvXBodtpcBq1Lhr8qK0t Modular_Synth_Amp_schematic - Dasha Palenova.JPG]
* [https://drive.google.com/open?id=1MPZkrqBoK5IpbC47xlKAPAsVKJ4K5zxD Modular_Synth_VCO_schematic - Dasha Palenova.JPG]
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== Step-by-Step Instructions ==

{{#widget:ProjectStep|inst=Build the function generator circuit. The input is just the power supply, and the outputs are a sine, a triangle, and a square wave. If you’re not comfortable with soldering immediately, build it on a breadboard first. Test to see if the duty cycle and frequency knobs work as expected. If soldering, be very careful with potentiometers - make sure nothing gets inside and no solder attaches to the base of the pot. Try to keep the wires as short and as close as possible to the chip to avoid random pickup. Optionally solder banana receptacles to output wires for better connection. I used -12V and 12V supply, but anything up to 36V pp (+18V and -18V) is safe. Despite the suggestion of the datasheet, I found that the circuit only works if pin 11 is connected to ground and not the negative rail. The datasheet also suggests you use a 1N457 diode, but I found that a basic orange Si diode from the lab works better. If you’d like more information about how the circuit works, read my attached presentation or consult the datasheet for the ICL8038 chip https://www.mit.edu/~6.331/icl8038data.pdf
|src=16wye0KVisYxx96uRjK5fYV1BgFc1wjQ1|show=img}}
{{#widget:ProjectStep|inst=Build the audio amplifier circuit. Test the output before connecting the speaker. Do the gain and volume knobs produce the amplification you expect? Again, solder the pots very carefully. The gain knob has one of the ends not connected to anything and the 10R resistor (R1) is actually 10 Ohm, not 10kOhm. Try not to connect input and output ground to the same line as it gets noisy. You can read about what the parts do in my attached presentation or on https://www.circuitbasics.com/build-a-great-sounding-audio-amplifier-with-bass-boost-from-the-lm386/
|src=18L_UrXswg4gGwP9TW05dc5GZypfJboQQ|show=img}}
{{#widget:ProjectStep|inst=Now you can build on this - for example, you can add high and low pass filters. You can use my schematics or design your own. I recommend using filter design tool by Analog Devices: https://tools.analog.com/en/filterwizard/
These normally utilize multi-stage filters, first stage being a simple buffered filter, connected in series with Sallen-Key filter stages. Sallen-Key filters are nice because they use a non-inverting amplifier, so voltage can stay at the same level as before the filter, and they are easily stackable for better results.
|show=none|src=none}}
{{#widget:ProjectStep|inst=Here you go, now you have a nice base to build off of when adding new modules! Consider adding a mixer, a VCA, and an LFO for more fun sounds.|show=none|src=none}}

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