Pulse Modulated Record Player

Introduction: Pulse Modulated Record Player

This project teaches you how to hack a record player to spin based on your heart rate. Essentially, we'll be gathering data from the pulse sensor via the Arduino. Then we take the average human range of BPM convert those to a value which controls the record player speed.

You will need:

  • Pulse sensor
  • An old record player
  • A record to test with
  • A SparkFun ProtoSnap (or other Arduino compatible board)
  • Soldering iron
  • Solder
  • Heat shrink tube
  • Heat gun
  • Multimeter
  • A solderless breadboard
  • Unstranded wire
  • 1kOhm resistor
  • TIP120 transistor
  • Alligator clips
  • Wire strippers
  • Screw driver

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Step 1: Unscrew the Back

First we want to unscrew the back of our record player. Be sure to place the screws in a container so you don't lose them. Be extremely careful as you open it. If any wires break, there will be no way to tell where they went. Document where the original wires go with a picture.

Step 2: Unscrew Knob Panel

Unscrew the green panel. Note that these screws are shorter than the ones from Step 1.

Step 3: Build the Arduino Circuit

Now we build the Arduino portion of the circuit. Essentially, we'll be gathering data from the pulse sensor via pin A0. Then we output a voltage based on the sensor data to the transistor via pin 10. The transistor then outputs the voltage to the record player motor, making it spin.

Step 4: Splice Into Motor

Next we want disconnect the motor ground from the record player ground. The pure white wire attached to the motor is ground. The white wire with a red streak is VCC. Cut the ground and strip each end.

Step 5: Test Voltages for Each Speed

Next we'll be testing the voltage for each RPM setting on the record player. Set the record player to 78 RPM. Attach the black multimeter probe to the positive wire on the motor. Attach the red multimeter probe to the positive wire on the record player (i.e. the other end of the white wire with the red stripe). Alligator clips work well for now, since we'll be testing the voltages of each playing speed. Eventually you'll want to replace the alligator clips by soldering longer cables onto the motor wires. Measure and record the voltage drop. Repeat for 45 and 33 RPM.

Note: If you solder wires, be sure to slide heat shrink tube over one of the wires before you solder so you can use a heat gun to cover the exposed areas.

Step 6: Attach to Arduino

Detach the multimeter and attach the record player and motor to the Arduino according to the schematic.

Step 7: Add the Code

Open the following Arduino sketches and upload them to your Arduino. What this program does is collect data from the sensor, then take the normal human range of BPM and breaking it into three smaller ranges. Each of those ranges maps to an RPM (33, 45, 78), which is then mapped to a value between 0 and 255. The final value is sent to the record player motor via pin 10.

Step 8: Test the Code!

Test the code on yourself and some friends.

If it works:

- well done! move onto the next step

If not:

- review the instructable

- read over the sensor documentation and sample code

- contact me and I'll try my best to help you out

Step 9: Reassemble the Record Player

Once you're sure the everything's in working order, it's time to put the record player back together. First screw in the green circuit board (remember, small screws!) Next, heat shrink the soldering around the internal wires (you put heat shrink over the wires before you soldered, right?) Finally, reattach the back panel and screw it in.

That's it! Enjoy your new pulse modulating record player.

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