Arduino Motor Control for the Spinning Night Light
Most motor control applications can be accomplished with a simple single-transistor circuit. This type of circuit controls the basic operation of turning the motor on and off, and allows very fast switching of the motor, which makes it possible to control the speed of the motor using pulse width modulation (PWM).
The basic problem with this circuit is that the direction of the motor cannot be reversed. For our simple application in this RGB LED night light, spinning the motor in one direction is enough. In the future we will use motors in applications which require us to reverse the direction as well, and for that we will be using the type of motor control circuit called H-bridge circuit.
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Arduino RGB LED Spinning Night Light: Assembly
Solder wires to motor terminals and cover with heat-shrink tubing
- Using a knife or sharp scissors, puncture a small hole (to fit the motor shaft snugly) on the center of the jar lid
- Solder motor shaft to jar lid (if necessary use hot gun or super glue, as some surfaces won’t “catch” the solder easily)
- Solder the RGB LED leads to long wires and cover the connections with heat-shrink tubing
- Build the circuit on the mini breadboard using the schematic as your guide
- Prepare the paper diffuser (use a hole puncher and punch a few holes to allow some light to shine through) and tape it around the jar lid using mounting tape
Arduino 2-Digit 7-Segment Display Counter: Circuit
This week we’ll look at the circuit for the 2-digit 7-segment display counter using the Arduino.
There are a few options to control multiple displays:
- employing multiple controllers;
- using a 7-segment driver chip like the 7447;
- using a multi-display controller such as the MAXIM MAX7219;
- sequencing through the displays, which is what we have done in our example, as it requires no added hardware.
When we were using a single-digit display, we connected the common anode pin to our Vdd supply, but with two digits we have to drive them independently if we want them to display different digits!
A natural reaction would be to try to use two Arduino I/O pins, each driving a digit of the display. The problem with this scenario is that it is not possible to drive the common anode or cathode pin using Arduino I/O pins, as they cannot source or sink enough current to light all seven segments.
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