Basically, you have the output of an opamp (Operational Amplifier) going into a sound system: in this case, a 1/4 inch jack into a mixer going to a speaker. Its only mono, but the skies the limit in terms of post-processing... Check out the included recording, for a glimpse of squawking fun :_)
SIDE NOTE: for circuit pros; dont use decoupling caps on the voltage regulator!
Step 1: Needful Things
- the 7414 opamp (sometimes called a Hex inverting Schmitt trigger)
- 9 volt battery
- a 9v battery clip
- 508 Voltage Regulator
- 1/4 inch TRS headphone jack
- An LED
- a 220 ohm resister
- THREE 10uF Capacitors, FIVE 0.01uF Capacitors (number 104), another cap of any size (experiment?).At least TWO light sensors
- various wires
- any kind of light-creating source (like a torch)soldering wire
- TWO potentiometers & TWO switches
You will also need a soldering iron, a multimeter and breadboard. See the second pic on how I clipped two wires to the multimeter so it can be used for testing on the breadboard.
NOTE: the images I included use extra jumper wires spread around the board so all connections can be seen easily. Normally you wouldn't need them and actually shouldn't, since they can add noise to the whole circuit.
Step 2: Soldering the Battery Clip and Setting Up the Power Supply
Second, set up the regulator. According to the opamp's datasheet, it should have a supply of around 5 volts. But our battery is 9 volts. You can use either an 805 voltage regulator, or a low dropout 2940 one, which basically uses less power than the 805. Either one will work.
Pin 1 should go to the raw 9 volts.
Pin 2 is Ground.
Pin 3 -s the 5 volts to supply the whole board.
This is all well and good, but this setup is always on. We will want to set up a switch, so that the baord can be turned on and off. Stick a switch in between the +9 volt battery clip and Pin 1 of the Regulator.
Next, lets set up a power LED, so we know if it is turned on or off. LED diodes are polarized, and we all know what will happen is we get the pins mixed up, dont we..... See the image to see how it can be breadboarded.
Step 3: Setting Up the Opamp
Next, Pins 1 and 3 should be connected to +5V and ground via a 0.01uF capacitor (number 104). In the image, I used red jumper wires for the two caps going to +5V, just for clarity.
Tech note: Essentially, the opamp takes input voltages on Pins 1, 3, 5, 9, 11 and/or 13 and spits out a digital signal on corresponding Pins 2, 4, 6, 8, 10 and 12. That gives a total of SIX sensors that can be used on it for extras squawking goodness.
Step 4: Add the 1/4 Inch Jack & Other Caps
Attach the ground wire (the one soldered that is connected to the inside metal tubing) to the board's ground and the other wire to the Ground side wire of the 47uF cap.
Now connect the other positive leg of the 47uF cap to the Ground legs of two 10uF caps.
DO NOT get the polarization wrong on these caps! The side with the big strip of black should always be heading towards Ground.
The other positive legs of the two 10uf caps should be connected to the opamp's Pins 2 & 4. I used extra jumper wires spread around the board so all connections can be seen easily on the image. Normally you wouldnt need them.
Step 5: Add the Photocell Sensors
Connect one photocell to the opamp's Pins 1 & 2 and another photocell to the opamp's Pins 3 & 4.
From now on, you should be able to hear some squarks from the circuit, if you plug in a pair of 1/4 inch headphones into the circuit's jack and shine some light on the photocells.
Feel free to swap out the caps for other values, to change the pitch(!)es.
Above is a recording I made of this circuit, but added three more photocells on the opamp's other input/output Pins (see last image). I plugged the circuit's output through my mixer and recorded the signal in Logic.