Week #5 - Journal

Ideation

Tell us about your assignment's idea for this week. Why do you care about this idea? What inspired you? (Please include images or links to sources of inspiration)

The theremin is a musical instrument played without the performer making physical contact with it. It has been used in film and television for soundtracks and sound effects.

The controlling section of a theremin is typically two metal antennas that detect the relative position of the hands to control frequency and volume with a single hand.

In preparation for my final project, I wanted to experiment with sound in electronics, especially since I'm considering adding an instrument mode. So I decided to create an optical theremin that uses photo-resistors instead of antennas to control pitch /frequency and adjusts volume through a separate knob.

And to fulfill the assignment requirements, I decided to connect an LED in parallel to the buzzer. As a result, the photoresistors also control the LED's blinking speed, while the knob controls the light intensity.

Tool Chain

Describe software, components, materials, and tools that you used in your assignment

Circuit Design AND Preparation

TinkerCad:

To create the design from scratch.

Circuit Implementation AND Testing

555 Timer
2 0.1 uF, 16 V Polarized Capacitors
1 MΩ Resistor
2 Photoresistors
Piezo
10 kΩ Resistor
1000 Ω Potentiometer
9V Battery
100 uF, 16 V Polarized Capacitor
Multimeter
LED RGB
0.39 kΩ Resistor
0.47 kΩ Resistor
Slide switch
Jumpers
Crocodile Wires
Breadboard

Enclosure (Lo-fi Prototype)

Cardboard Box
Cutter

Design/Preparation Process

Describe the design of your circuit. What are the action components that you used? Which voltage source did you choose? Why? How did you simulate your circuit on Tinkercad. (Make sure to include a screenshot of your circuit wiring on Tinkercad and a video recording for your circuit simulation on TinkerCad)

I decided to use the 555 timers in astable mode. This means the circuit is fed by an RC circuit to generate an output square wave. This squarewave will be fed to both the blinking LED and the Buzzer.

http://www.falstad.com/circuit/e-555square.html

By altering the RC circuit that we are feeding into the 555 timer, we can change the frequency of the output square wave to play different notes. So for that purpose, I used an LDR, so that the frequency (tone) will change depending on the light to the sensor.

The amplitude (the volume and the light intensity is controlled by the potentiometer.

Circuit design Swanky Lappi-Blad _ Tinkercad - Google Chrome 2022-02-14 17-31-26.mp4

I connected both the LED and the buzzer to resistors after several trials and calculating the minimum current they needed to operate, to make sure that they will be functional at all times I chose them with the dim lights (lowest values on both LDRs) and the lowest value on the potentiometer.

And I didn't connect the G leg of the RGB LED because I only wanted it to be shades of purple.

Development/Implementation Process

Describe how you implemented your circuit on a breadboard and integrated it within the device. And most importantly, show us the final outcome of the assignment (Make sure to include a video recording for your device while functioning

First I placed the 555 timer IC and made the required connections using the astable mode schematic I found online and placed the LED and the Buzzer on the output pin.
Then I connected the potentiometer's wiper to both the LED and the Buzzer.
Then I connected the 9v adapter and connected the slide switch on it so that it makes an open circuit

After I tried it I made a hole in the box and mounted the potentiometer and used a cardboard piece I've found to mount the LDR (using male-female jumpers), and a button (using the crocodile wires), and the rosette.

VID-20220307-WA0004.mp4

20220307_172254.mp4

VID-20220307-WA0003.mp4

Making a siren sound with the opto-theremin

Community of Learning

Did you ask for feedback? What are the ideas that others have contributed or suggested? What was someone else’s idea that you built upon? How did you help your peers? How did your peers help you?

During the first session of the week, Saeed mentioned Falstad, which I used to better understand and visualise the function of this circuit.

Also in the Hands-on Minds-on activity, one of our peers, Eman, told us that she couldn't wire the rosette properly, and so did I, but our peers Mahfouz and Sharkawi came to our aid and showed us how to wire them with a screwdriver.

It turns out that I need to loosen the nails first, then place the jumpers.

Overcoming Challenges

Describe problems and challenges that you faced, and briefly describe solutions. How did you use the Avometer to troubleshoot problems?

I started with a 9v battery as the power source, but the buzzer was making a very faint sound, so I used the Avometer and realised that the battery wasn't providing enough current to the buzzer, so I replaced it with the 9v adapter that came with the HitTheGame kit during week 0.

Assignment Design Files

Design [BRD]

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