Finger High-Striker
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Step right up! Are your digits strong enough to make it to the top?
This device makes use of a homemade pressure sensor.
Compressing the device changes its resistance which in turn alters the flow of current. The induced voltage drop is recorded by the analog input of the Arduino and given a value between 0 and 1023.
This value will then be used to manipulate the brightness of our LEDS.
The more forced applied to the sensor, the less resistance, the lower the voltage drop, the higher the recorded value, the more LEDs turned on.
A capacitor was added between the analog input and ground to stabilize the readings.
The more forced applied to the sensor, the less resistance, the lower the voltage drop, the higher the recorded value, the more LEDs turned on.
A capacitor was added between the analog input and ground to stabilize the readings.
| Component | Quantity | Description | Where to Buy |
|---|---|---|---|
| 10 kΩ Resistor | 1 |  |
Canada, USA |
| 1 kΩ Resistor | 8 |  |
Canada, USA |
| Homemade Pressure Sensor | 1 |  Red |
Canada, USA |
| Insulated Wires | ~23 |  |
Kit or M/M Cables |
| White LED | 8 | 
| Canada |
| Red LED | 8 | 
| Canada |
| Ceramic Capacitor 0.01 µF | 1 | 
| Canada |
| Anti-Static Foam Sensor | 1 |
| Insructable on how to build |
| Arduino Uno | 1 |  |
Board with Accessories |
The first thing we'll do is connect all eight LEDs. I've spaced each LED apart by four slots.
Each LED needs to have a 1 kΩ resistor in series with it, connected directly to the shortest pin (cathode (-)).
Connect the longer pin (anode (+)) directly to ground using small pieces of wire.
NOTE: LED is short for Light Emitting Diode, and all diodes have polarity. If the pins are reversed, the LED won't work
The left-most LED will be associated with pin 13. Each consecutive pin will be associated with the next LED, all the way to the red LED which will be assigned to pin 6.
Attach your custom pressure sensor to the left-end of the breadboard. Make sure the connectors are on opposite sides of the middle divider.
Connect a wire from the 3.3 V pin all the way to the far side of the pressure sensor. This is what allows current to flow through the sensor.
Connect a wire from the 3.3 V pin all the way to the far side of the pressure sensor. This is what allows current to flow through the sensor.
Next we'll add our 10 kΩ resistor and 0.01 µF capacitor. We want one pin for both components connected to the pressure sensor.
The other pins will be given their own row.
These two components are connected in an arrangement called parallel. The voltage across each component is the same; however, the current is split.
These two components are connected in an arrangement called parallel. The voltage across each component is the same; however, the current is split.
Our last step is to connect the sensor to the Arduino in a way that allows data to be recorded.
This is done by connecting a wire from the closer side of the pressure sensor, all the way to the A0 (ANALOG IN) pin on the Arduino.
And finally, we must ground everything by connecting another wire from GRN to row with the resistor and capacitor.
When every thing's finished, it should look similar to the image on the left.
Source Code:
Considerations:
The control statements have been adjusted for my environment. Working on an ungrounded laptop meant lower readings for total1, 2, and 3. I called the notePlayer functions whenever these values were greater than 500.
If you are working on a laptop, plugging in the charger will ground the device and provide higher readings. This will vary from computer to computer, so the best thing to do is run the Serial Monitor (Tools > Serial Monitor) and customize your if-statements based on the readings.