The RGB theremin is a fun little gadget that will let you play with mixing Red, Green and BLue light to make different colours, just like what happens on your television or computer screen. This page tells you how to construct it. You will need a fine tip soldering iron, solder "wire", side cutters and a screw driver. You will also need to buy a 9V battery.
NOTE: If you are not confident in doing this assembly on your own, remember that as a member of Melbourne PC User Group you can get help. We have an electronics workshop almost every Saturday from about 1pm to 4pm where you can come in and find someone to help you with guidance and tools.
Here's a schematic:
It pays to assemble and solder the components to the board in the "right order", starting from the lowest profile components and working up to the tallest ones. All soldered in parts go on the "top" of the board, which is the side with the white component markings.
There are two resistor values: 1K (1,000 ohms) and 1M (1,000,000 ohms). The board itself is clearly marked with component values. You can recognise the 1K resistors by the red colour band on them. On the 1M resistors the equivalent band is green, Make sure you don't mix them up. Insert the resistors, solder them and cut off excess leads. Resistors are symmetrical (they don't have + and - pins, so it doesn't matter which way round they go.
Hint: If you have a "Third Hand" holder it works quite well to hold the board in the 3rd hand and top solder the resistors. This is a through hole plated board, so that works. If you don't have a third hand insert the ristors, lay a flat piece of material (a piece of cardboard, a hardcover book, whatever) over them then set it down on the table with the leads pointing up. Then solder (bottom soldering).
The LDRs are the round components with two wires. The board is clearly marked with where they go. Insert them and solder fairly flush with the board. LDRs are symmetrical.
These are the black parts with 3 wires. Note the orientation very carefully on the picture and the board markings. As you push them into the board (making sure all 3 pins go through!) , the pins will generally splay apart and hold the transistor in place. If you are new to this it pays to insert and solder one at a time.
If you look carefully at the LED (that's the part with 4 leads) you will notice one lead is longer. That goes into the elongated solder pad. It's a good idea to install the LED up off the board.
Solder the wires from the battery clip into the board. Be very careful to get the red lead in the hole marked with a plus sign! You may wreck the board if you put in the wrong way around.
The battery clips screw on under the board. It doesn't matter which way around they are, so long as they are the same. The collimator goes on top, over the LDRs.
To try out your new toy clip the battery clip onto a 9V battery. Now experiment with covering the holes in the plastic collimator. The LED should light up in different colors. If any LED fails to totally extinguish when it's not covered (in darkness) it probably means the room (ambient light) is not strong enough.
Be sure to unplug the battery clip whan you are finished playing.
Special note: The components for this were bought off eBay. If you are electronics savvy you may work out that the BC517s appear to be the wrong way around. The reason is that the transistors we bought (ever so cheaply!) are actually MPSA13's marked as BC517. MPSA13 and BC517 have exactly opposite pinouts!!!! The board marking is designed to to accommodate the fake BC517s. So have faith, and follow the board markings.
3D printer files