This is a very simple and very fun breadboard project. Once you have everything you need it doesn't take long to assemble.
Yes, it does work!
I actually made this project once while doing experiments with the Elenco breadboard educational kit. It is built from "EXPERIMENT #36: DRAWING RESISTORS" page 52 from the kit called "BASIC ELECTRONIC EXPERIMENTS MODEL PK-101". I changed it up slightly for the purpose of making a smoother tutorial.
Power supply (either a 9 volt battery connector and battery or a DC 9 volt power supply and jack with lead wires)
Wires (an assortment of sizes with the ends trimmed bare and tinned would help)
Small Switch (on-off or on-on will work fine)
Speaker 16 Ohm 25 W (Actually just about any little old speaker will work)
Audio Transformer (you can pick one up at Radio Shack for about $3)
Capacitor Ceramic 0.047uF
Paper (a nice piece of card stock would be nice)
No 2 Pencil
For so many of my projects I scavenge my parts from old electronics that are worn out. That saves a tiny fortune on parts but the cost of most of these parts brand new is probably under $10 especially if you order from a place like http://www.taydaelectronics.com
I was disappointed they didn't have the Audio Transformer but I did look it up and found it available at Radio Shack.
Step 1: Connect the Power Supply
You can either use the 9 volt battery option or do like I did and use and old 9 volt power supply I had from something else.
For my breadboard projects I like to use a steady stream of power. With batteries, a power drop in the battery can affect the results. Plus I save the batteries for portable projects or when I actually go to build the project into a box.
For my breadboard projects I took a power socket off of some old electronic device and soldered red, black, and white wires onto the leads. The extra wire is for if I want to utilize the built in switch that is in the jack. The switch could potentially switch to back-up battery in the event that the unit comes unplugged from the wall unit.
Step 2: Add a Power Switch
The switch I use has three prongs and is an on-on switch so that you send a signal from the center prong to either of the outer ones. In this project I simply use the switch to cut the power to the rest of the circuit.
Step 3: Power to the Switch
Notice the letters and numbers on the breadboard. The holes can be individually identified by their letter-number coordinates. All the holes in a number row are connected to each other. But the holes in letter rows are separate. By pushing the purple wire into row with the #5 it is thus connected to the left prong of the switch. On my particular breadboard all the holes next to the red line are connected, known as the red rail; and all the holes next the the blue line are connected, known as the blue rail. The red and blue rails are usually used for power, red for positive and blue for negative. The rails on either side of my board are not interconnected so if I want power on the other side I use a wire to jump across. This project is small so there is no need to do that.
I have several different wires I use for projects. Most of them are trimmed nicely and then "tinned" with solder. Then I wrap the ends with electrical tape and put a bit of plastic model kit glue to keep them from unwinding or sliding up when I push my wires. The other wire I like to use is copper telephone wire. As you can see by my pictures I like to cut some smaller wires with the ends trimmed so I can quickly make a jump between two holes that are close to each other.
Step 4: Add the Transformer
The transformer has three wires on one side and two on the other side. If you will notice on the schematic the transformer is next two the speaker. The two back leads go to the speaker wires. The side with two wires is known as the secondary side. The side with three wires is known as the primary side. On the schematic you can see a P and S accordingly.
Step 5: Connect to the Transformer
Step 6: Add the Transistor
Transistors are much like a diode in that they can be used to send current in one direction and not allow it to flow back the other way. You always need to make sure you put the transistor in the right direction.
Step 7: Add the Capacitor
The ceramic capacitor used here is 0.047uF but is marked with the number code 473. When you are using many different ceramic capacitors it is important to be able to read and identify them by their markings. This can get tricky because not all manufacturers mark them the same. The nice thing about ceramic capacitors is that it doesn't matter which way they face on the board. With electrolytic capacitors they have to be put on facing a specific direction because they have a plus and minus side.
Step 8: Add the 3.3K Resistor
Step 9: Add the 10K Resistor
Step 10: Connect the Probes
Take the second wire and put one end in the same numbered row as the left lead of the transformer. The other end of the wire is loose.
The probes are the two longer wires we will use to touch our drawing and make music.
Step 11: Connect the Negative Power Rail
Step 12: Connect the Speaker
Step 13: Test the Circuit
If that doesn't work first make sure your power is connected. If it still doesn't work you have to go through the board and make sure the wires are making good connections in their holes.
If there is no sound you don't have to keep holding the loose ends of the probes together just find a numbered row that is empty and plug the ends into the same row on the same side of the board. If a connection is loose somewhere just touching a wire might turn the circuit on and suddenly give you the sound indicating which wire is loose. If several wires are loose then you will have to secure them before anything will work.
If you think the connections are all solid then make sure the components are lined up with each other properly. Sometimes you may inadvertently put a wire in the wrong hole thinking it was in line with it's corresponding component. It is very easy to do with the switch because it may be flush with the board and you can't see which rows the prongs are in.
Step 14: Test Your Drawing Skills
Step 15: Make Some Noise, Maybe Some Music
If you are having trouble getting a consistent sound you may need to go back and make the triangle darker. Make sure you use a fairly sharp pencil. It may also help to get the tips of the probes moist.
If you want to make music you can wing it by trying to touch the right probe in positions that sound in tune with your melody. If you want to be more precise take a pen and make marks above the triangle to indicate the positions of your notes. Experiment with different shapes and drawings and see how that affects your results.
If you want to go on to make this project something more permanent check out my next Instructable!
Also check out my Youtube Demo video to get an idea of where you can go with this project.