Introduction: Moldover's Light-Theremin CD (DIY Version)
Hi! I'm Moldover. I make music and I make musical instruments.
I released my first original album (self-titled) as Moldover in 2009. The Awesome Edition of this album came on a CD mounted onto a custom-designed circuit board that is also a musical instrument. This instrument is a simple, self-contained, analog synthesizer called a Light-Theremin.
I enjoy helping people learn how to make cool stuff, so I also created the "DIY Awesome Edition" of the album, which is essentially a kit so you can make your own Light-Theremin. This instructable will teach you how to assemble one of these kits, and you'll learn some basic soldering skills in the process. For more info about the original project and a demonstration of the Light-Theremin, watch the video above. if you'd like to order a kit, or some of the other cool things I make, please visit my webstore.
Step 1: Step 1: Gather Tools
To assemble your Light Theremin kit, I recommend the following tools:
- Soldering iron (15 - 30 watt irons are good for small electronics)
- Moist sponge (used to clean excess solder from your iron)
- Solder (I use rosin core, 60% tin / 40% lead, .032 inch diameter solder)
- Flush cutters (flush cuts are necessary to fit the finished Light-Theremin into the CD jewel case)
If you have not soldered before don't worry, it's easy! The basics are briefly covered here. If you want a little practice before you start building your Light Theremin, there are several good instructables that will teach you, or you can learn from the wonderful Soldering is Easy comic book.
Step 2: Gather Parts
Each DIY Awesome Edition kit contains:
- 1 150-Ohm resistor (the physically larger of the 2 resistors)
- 1 1k-Ohm resistor (the physically smaller of the 2 resistors)
- 2 capacitors
- 1 LED
- 2 photo resistors
- 1 battery
- 1 battery clip
- 1 556 timer (an integrated circuit that looks like a "micro-chip")
- 1 headphone jack
- 1 button
- 1 CD-hub (might be stuck in the center of the CD)
- 1 speaker
- 1 CD
- 1 circuit board
- 1 plastic CD jewel case (not pictured)
I recommend keeping all the little components in the empty plastic jewel case while you work. That way they won't get lost, but are still easy to get to when you need them.
Step 3: Prepare Your Soldering Iron
Plug in your soldering iron. If it has an on/off switch turn it on. It will take at least a few minutes to get hot. If an extra blob of solder or some unwanted gunk has attached itself to the tip of your iron, it may be helpful to clean the tip by rubbing it across the wet sponge.
"Tinning" the tip of the iron is also a good idea. To tin the tip, push some fresh solder onto it and rotate the iron, so as to cover the entire surface of the tip with solder. Wipe any excess solder blobs off onto the sponge. The tip should now be covered with a thin layer of shiny silvery solder.
Step 4: Place the First Component
Let's start by placing one of the easiest components to work with: a capacitor. Find the location where it will be placed by looking at the white silkscreen markings on the "component side" of the circuit board. Find one of the two silkscreen markings that matches the shape of the capacitor and has its value of 0.1mF marked on it. Push the leads of the capacitor through the holes in the board and pull it through from the opposite side so that the capacitor itself sits as close to the board as possible. Bend the capacitor down flat against the board, directly on top of its picture. Flip the circuit board over so that the leads are sticking up. This is the "solder side" of the board. Bend the leads apart so that the component cannot move around or slip back out of the holes.
NOTE: In the end, the finished Light Theremin will go into the CD jewel case, which is very thin. In order to make sure it fits, most of the components must be placed as close to the circuit board as possible. This is why the capacitors (and also the LED) must be bent down flat against the circuit board. Please refer to the pictures above for a visual explanation.
Step 5: Solder the First Component
Place the board with the component side down on the table. The capacitor should be squished between the board and the table, and the leads should be sticking up towards you. We will be using solder to connect one lead of the capacitor to the circle of copper that surrounds the hold it is sticking through. These copper-plated holes are called "vias".
Hold the soldering iron in your dominant hand, and a piece of solder in the other hand. Place the tip of the iron against both the component lead and the via. You must hold the iron against both of these pieces of metal at the same time for about 5 seconds to allow for them to heat up. With the iron still pressed against these two pieces of metal, use your other hand to push some solder into the connection. Allow another few seconds for the solder to adhere (or "wick") to both pieces of metal. Pull the iron away and the solder will quickly cool and harden making a smooth, continuous, and strong connection.
Step 6: Cut the Leads
WARNING: when you cut leads, bits of sharp metal often fly up in the air and can poke someone in the eye. A good strategy for avoiding this is to block these metal shards with one of your hands. First place the cutters where you intend to cut, squeezing them gently so that don't slide around. Cover the whole area where you are cutting with your other hand, while you make the cut.
Use the flat side of your flush cutters to remove the unnecessary ends of the component leads.
TIP: After cutting, you may still have a little stump of a lead sticking up, or a big bump of solder that bulges out from the circuit board. If any stumps and bumps like this are too big, they will make the finished Light-Theremin too thick to fit in the CD-jewel-case. Try to cut the leads very close to the circuit board. You can even cut into the soft bumps of solder. Just be careful that don't dig in SO deep that you rip up the copper from the board itself.
Step 7: A Few More Simple Components
Place, solder, and cut away the leads for the other simple components:
- The second of the two capacitors
- 2 photo resistors
- 1 150-Ohm resistor
- 1 1k-Ohm resistor
- 1 button
After finishing all of these, you should be comfortable with the basic soldering process.
Step 8: Special Tip: Preparing the Battery-pad
On the component side of the circuit board, beneath where the battery clip goes, there is a large square-shaped area of metal without a hole. Metal areas of any shape like this without holes in them are called "pads". Heat up this pad with your soldering iron and melt a little bit of solder onto it. Spread the solder around with your soldering iron to make a thin pancake-like shape.
Later, when we install the battery, this pancake will help the battery make a strong electrical connection to the circuit board.
Step 9: Components With Specific Orientation
Some components must be placed in a specific orientation or else they will not function properly. For example, the LED has a positive lead and a negative lead. The positive lead for this LED (and for most LEDs) is slightly longer than the negative lead. Look at the silkscreen markings on the circuit board to match the positive lead with the positive via, and the negative lead with the negative via.
Several other components require specific orientation. Be extra careful when placing these:
- Battery clip
- Audio jack
- 556 timer
If you place them incorrectly and solder the connections, it can be very difficult to un-solder them later, after you discover the mistake.
Step 10: Special Challenge: the Speaker
The speaker presents a special challenge. Unlike most of the other components which have firm, bare-copper leads, the speaker has thin, flexible wires, with only a tiny bit of copper exposed at their ends. Find the two pads on the circuit-board where the speaker-wires connect, and use this special technique:
If the two speaker wires are twisted together, un-twist them so that they can be spread further apart. This will make them easier to work with one at a time. Putting the speaker aside and using only the soldering iron and some solder, heat up one of the pads on the circuit board and melt enough solder onto the pad to cover it with a large bubble. Pull away and let the bubble cool onto the pad. Now, holding the soldering iron in one hand and the speaker in the other, reheat the bubble on the pad so that it becomes liquid again. Insert one of the speaker-wire tips into the liquid bubble. Keep the wire inside the bubble and remove the soldering iron. The bubble will cool and harden with the wire still inside, making a strong connection between the wire and the circuit board. I recommend gently pulling on the wire to test if it is strongly connected to the bubble.
Repeat the above procedure with the second connection to the speaker.
Remove the sticker-cover from around the face of the speaker, and stick the speaker face-down to the circuit board.
Step 11: Attaching the CD-hub
The CD-hub is simply a sticker that sits in the center of the circuit board and holds the CD in place. We must cut a hole in the sticky-back of the hub so that it will fit over the LED.
Remove the white paper backing from the CD-hub. Use your cutters to make a hole in the center of its exposed sticky-backing. Stick the CD-hub down into the very center of the circuit-board around the LED. Press firmly all around the CD-hub to ensure that it is strongly attached to the circuit board.
Step 12: Powering Up and Testing
Insert the battery into the battery clip, making sure that the positive side is facing away from the circuit board. Press the button to test the circuit. The LED should illuminate and sound should come from the speaker. If you do not see the LED illuminate or if you do not get sound, skip ahead to the next step for trouble-shooting and come back here afterward.
Tip: Remember that all the leads (even short leads like those on the 556 timer) must be cut very close to the solder side of the circuit board if you want your Light-Theremin to fit into the CD jewel case. I often go over all these cuts at this point in the process, and if they are poking out I try get them close to flat.
Congratulations! You have assembled a Light-Theremin! Put the CD on the CD-hub, put the circuit board into the CD jewel case and you're done!
Step 13: Trouble-shooting
If for some reason you don't get sound from your Light-Theremin, here are some troubleshooting questions to ask yourself:
Are you in a very dark place, or a very bright place (like outside)?
If you are, the pitch of your Light-Theremin will be so low or high that humans cannot hear it. Find an indoor space with comfortable ambient lighting and try it again.
Are you in a very loud place?
The volume of the Light Theremin's built-in speaker is very quiet compared to the general noise level of parties, restaurants, or city streets. Try a quieter location, or simply connect your Light Theremin to headphones or a sound system.
Are all your soldered connections strong?
Often you can make a weak connection stronger by "reflowing" it. Touch the tip of the soldering iron to a connection for a few seconds so that the solder re-melts, then remove the soldering iron and let it cool. If there is not enough solder on the connection to re-flow it, just add a little more. Sometimes I do this quickly with all the connections, just to be 100% sure the are strong.
Is there a short-circuit somewhere?
If you use too much solder on a connection you might be connecting two points that were never meant to be connected. This is called a "short circuit". Short circuits can also happen if you are not careful about containing the solder to the area of the pad or via where you are making a connection. Look carefully at all your connections, especially connections close to other copper features (such as the track-name lettering on the back-side of the circuit board). Also, look carefully at connections close to other connections, such as the many leads on the 556 timer. Make sure none are short circuited by mistake. If you think you have located a short-circuit, it may be necessary to remove some solder to repair it. Sometimes you can do this by simply re-heating the solder and pushing it away with the soldering iron. Other times you may need a special solder-removal tool such as de-soldering braid or a solder-sucker.
Have you double-checked component orientation?
It may be helpful to revisit Step 9, which covers component orientation. It's possible you may have put one or more of these components in backwards. It is easy to put the battery in upside-down, so don't hesitate to push it back out of the clip a pen or paper-clip. Check and make sure the positive side faces away from the circuit board. Note that the 556 timer has a semi-circular notch at one end, and not at the other. This notch should face in towards the middle of the circuit board, and NOT away towards edge of the circuit board. With the LED, if you have already soldered it down and cut its leads, it is difficult to know if it is in backwards or not. If the Light Theremin makes sound, but the LED does not light up, it is possible that the LED went in backwards and should be flipped around. The battery clip and audio jack are difficult to place backwards and so they are unlikely to be a problem, but you might want to compare how they look on your Light Theremin to the picture above, just in case.
If none of the above trouble-shooting ideas fixes your Light Theremin, I suggest bringing it to a friend who is more experienced with soldering and electronics.
Step 14: Thanks!
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Step 15: THE END
Thanks for building a Light-Theremin-CD! If you enjoyed this project, please let me know! If you'd like to check out my other projects, please visit http://moldover.com
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