GetLoFi – Circuit Bending Synth DIY

***** THERE ARE NO MORE GREEN BOARDS****

*****Deluxe uses the same circuit board as the standard kit****

** Instructions are currently being updated **

The APC 2.0 Deluxe Kit is exactly the same base circuit except with extra features and parts. The two main sound features are the addition of a Photo-resistor and the Capacitor Bank. Both of these features help to shape the sound coming from the unit. The Photo-resistor changes resistance based on ambient light and it connects in parallel with one of the potentiometers. This allows the APC to change the tone frequency and play melodies from pattern Light as well as Theremin like operation. You can use an included switch to connect the photo-resistor in Parallel with either potentiometer. The second feature is a Capacitor Bank that can be switched ON via the 2 extra buttons. Once the extra capacitors are added, the tone will shift down in Pitch when the buttons are pressed and held. Third feature is a Hold switch that when connected in parallel with the Trigger Button will hold the tone. Other items included are Knobs, Speaker, an ultra Bright LED, and assorted colorful wire.

Photo Resistor Suggestions:

The Photo-resistor can be tuned by adjusting the Potentiometer with which it is connected in parallel. Various sources can be used to modify the pitch, some examples include: Blinking computer lights, LED Tea Candles, LCD screen playback, TV, tree shadows, etc.

Step by Step:

To assembly this circuit board you will need something with a clip to hold it steady. Place the IC into the circuit board, make sure the divot is facing towards the APC Logo at the top. Now without flipping the board over, touch the legs of the IC with Solder and a Soldering iron. Everything should flow nicely down to where the placed hole is and solder in place.

Next place all the capacitors and in a similar fashion heat up the legs from the top to make the solder flow down and through the plated holes. The values are from the left: 0.022uF (223), 0.1uF (104), 0.01uF (103), 0.1uF (104), 1.0uF. Make sure the values are as indicated in the picture and that the Electrolytic Black Capacitor’s minus sign is facing towards the bottom edge.

Last component to go on is the 1K resistor. Now its time to install all the wires and the potentiometers.

Capacitor Bank Buttons act as bridges to connect the extra capacitors in parallel with the existing 0.01uF capacitor in order to drop the pitch. The photo resistor wire is used for connecting a light sensing resistor in order to modify the sound by changing the ambient light around it. Trigger button simply connects the Ground from the battery compartment to the entire circuit.

Battery compartment is connected this way, Do not switch the orientation of the black and red wires. This will cause the unit to not function.

The last lets add the output wires. These go to the 1/4 inch Jack and share a pad with the positive connection. Unlike most instruments and circuits the APC works by having the Positive Voltage as the common on the output instead of Ground.

Last components to add to the circuit board are the potentiometers. You also have the option of using wires to extend those based on the case in which you will mount the circuit. Note that you only need 2 wires to extend the pots. 2 of the pins share the same connection, so one of the outside pins can be left unconnected. Center Pins MUST be connected however.

Now the 1/4 inch output jack can be connected to the Output wires from the circuit board. Observe which side of the jack wires are connected. Looking from the bottom circuit board wires must go on the right side, speaker wires must go on the left side. Otherwise you will get no sound out.

The Output Indicator LED can be connected directly to the speaker, note that it will be dis-engaged with you plug the unit into the external amplifier. If you would like to have the LED always show the status of the signal you can connect it to the same legs on the Jack as the output wires. This about sums up the steps needed for the internal wiring. Following steps are for mounting your unit in a case. Of course try and see if your APC is making noises by connecting the battery and shorting the two trigger wires together. A tone should sound, if not, go through picture by picture and make sure your components are facing the correct way and wires are where they should be.

If this is your first project, perhaps you should use a plastic case that can be easily drilled. Maybe a kits lunch box or a topper ware container, or a VHS clear case. The best solution for making holes is to use Step bits.  They look like pyramids upside down and each step makes a bigger hole. This eliminates the need for a collection of many sizes of bits. Make sure there is enough room inside the container to house all the components comfortably. The Trigger button can be installed first and wired up. The hold switch is wired in parallel with the button to simulate the press of a button, keeping the tone steady.

Audio output jack can be installed next. Make sure there is enough room to close the lid if your case has one.

When installing the Cap Bank buttons make sure they are comfortable located so you can reach them with your fingers. The advantage  of mounting the potentiometers on the circuit board is that you don’t have to worry about fixing the board in place. Be careful drilling the holes for the Pots, make sure they are correctly spaced, measure twice.

If you are working with plastic the installation of the photo resistor is pretty simple, carefully heat the legs and very slowly push the component through the plastic or you may drill some little holes for the legs.

The second switch is used for turning on the photo resistor, basically connecting it to the set of wires. It is very sensitive to the light considerations and relative darkness needed, also the settings of the potentiometers make a difference in tones.

Now it you can mount the speaker and the battery case. Make sure there are holes drilled for the speaker to move air through. Otherwise it will be muffled and quiet. Double sided tape or hot glue can be used to hold the battery case in place.

Here is a view from the top of my completed project. Everything is in place and the case closes. Semi-transparent cases are nice because you can see through all the neat wiring inside.

Finished Project! The White Output LED is strategically placed under the plastic frog to light up the design.