In this Instructable I’ll show you how to make a electronic dashboard for a bicycle. We’ll be using an Arduino and a few off-the-shelf parts to create a system with light control and an LED speedometer.
Step 1: Materials
Arduino Micro (RadioShack #: 276-258)
12V 10W halogen bulb (RadioShack #: 272-011)
(2x) 12V lamp (RadioShack #: 272-336)
(6x) LED holder (RadioShack #: 276-080)
(3x) green LED (RadioShack #: 55050659) web only
(2x) yellow LED (RadioShack #: 276-021)
red LED (RadioShack #: 55050657) web only
1 uF capactior (RadioShack #: 55047769) web only
(6x) 330 ohm resistor (RadioShack #: 271-1315)
(4x) 10K ohm resistor (RadioShack #: 271-1126)
(3x) N-channel MOSFET (RadioShack #: 276-2072)
74HC14 Schmitt Trigger (RadioShack #: 55050984) web only
reed switch (RadioShack #: 55050593) web only
on/off toggle switch (RadioShack #: 275-602)
(2x) SPST toggle switch (RadioShack #: 275-612)
(6x) terminal block (RadioShack #: 55055598) web only
(2x) 4 cell D battery holder (RadioShack #: 270-396)
(8x) D battery (RadioShack #: 23-2220)
(16x) 8-32 x 5/8″ screw
(16x) 8-32 nut
(4x) 4-40 x 1/2″ screw
(4x) 4-40 x 1.5″ screw
(8x) 4-40 nut
~40″ double sided Velcro
.2 inch plywood
Step 2: Build the Circuit: Schematic
The circuit is composed of five main parts:
Power: Eight 1.5V batteries in series will give us ~12V. This system is attached to a large SPST toggle switch for control.
Debouncer: The reed switch is connected across the capacitor of an RC circuit. The analog output is fed into a 74HC14 Hex Inverting Schmitt Trigger which converts it into a digital signal, which is then fed into Arduino Micro interrupt 1 (digital pin 2). This chip is powered by the 5V from the Arduino.
Speedometer: Six LEDs are attached via current limiting resistors directly to the digital output pins of the Arduino.
Lamp Control: Three lamps are connected to N-channel MOSFETs. Each MOSFET has a 10k pulldown resistor on its gate pin, which is control by a digital output pin.
Step 3: Build the Circuit: Assembly
First we’ll attach the wires for the taillights. Cut four 36 inch lengths of wire and solder them to the lamps. The lamps do have polarity, so keep note of which wire is your anode or cathode.
Solder a few inches of wire to a terminal block. This will be the attachment for the lamp.
Attach two lengths of wires to each of the toggle switches. A few inches should do.
Take the LEDs and slide them into the rubber stoppers. Solder a few inches of wire to each.
Place the Arduino Micro on the proto-board with the micro USB connector facing out.
Place three terminal blocks along the edge with one of the pins in the power rail and the other in the main rows.
Place two terminal blocks with both pins in the power rail near the Arduino.
Place the MOSFETS on the board with the drain (the middle pin) aligned with the terminal block.
Place the 74HC14 to the left of the Arduino with the divot facing left as well.
Place a 10K resistor across the 74HC14 from pin one to pin fourteen.
Read more: Bike Dashboard