The low-powered device consists of a PIC micro-controller, an LDR (light dependent resistor) for light sensing and a low current relay which switches between the two modes. Here in this project “LDR Based Line follower Robot Car using PIC Microcontroller”, I used two different Motors for different wheels for controlling the movement and maintaining the direction. In bellow diagram described how the direction of rotation control accordingly sensors output.
In a regular DC motor, the amount of torque the motor exerts on the shaft is proportional to the amount of current flowing through the motor. A simple way to control it is by varying the voltage across the motor; more voltage means more current which means the motor pushes harder against its load which means the shaft turns faster.
When using a servo, however, you don't control torque or velocity. Instead, you specify what angle you want the shaft at. In other words, you have positional control of the motor.
Inside a servo is a traditional DC motor, a potentiometer (variable resistor), and control circuitry. The potentiometer is connected to the motor such that when the motor shaft turns it also turns the potentiometer. The controller can then measure the voltage at the center pin of the potentiometer and get an indication of the shaft's position. The controller receives a signal (see next step) from the user that sets a desired position. The controller compares the desired position to the current position of the motor and uses that information to turn the motor in a direction that minimizes the error.
The way this works in practice is you specify the angle you want the shaft at using your PIC, the shaft turns to that position, and then holds there. The further it gets pushed away from that position, the harder it tries to turn back. Hobby servos are usually geared way down, so even a wimpy $15 or $20 one can hold its position reasonably well.
When using a servo, however, you don't control torque or velocity. Instead, you specify what angle you want the shaft at. In other words, you have positional control of the motor.
Inside a servo is a traditional DC motor, a potentiometer (variable resistor), and control circuitry. The potentiometer is connected to the motor such that when the motor shaft turns it also turns the potentiometer. The controller can then measure the voltage at the center pin of the potentiometer and get an indication of the shaft's position. The controller receives a signal (see next step) from the user that sets a desired position. The controller compares the desired position to the current position of the motor and uses that information to turn the motor in a direction that minimizes the error.
The way this works in practice is you specify the angle you want the shaft at using your PIC, the shaft turns to that position, and then holds there. The further it gets pushed away from that position, the harder it tries to turn back. Hobby servos are usually geared way down, so even a wimpy $15 or $20 one can hold its position reasonably well.
It’s one thing to assemble your own circuits from scratch using off the shelf components. It’s quite another to build the components first, and then build the circuit.
That’s the path [Joris Wegner] took with this video distortion effects box, dubbed PHOSPHOR. One might wonder why you’d want a box that makes a video stream look like playback from a 1980s VHS player with tracking problems, but then again, audio distortion for artistic effect is a thing, so why not video? PHOSPHOR is a USB MIDI device, and therein lies the need for custom components. [Joris] had a tough time finding resistive optoisolators, commonly known as Vactrols and which are used to control the distortion effects. He needed something with a wide dynamic range, so he paired up a bright white LED and a cadmium sulfide photoresistor inside a piece of heat shrink tubing. A total of 20 Vactrols were fabricated and installed on a PCB with one of the coolest silkscreens we’ve ever seen, along with the Sparkfun Pro Micro that takes care of MIDI chores. Now, distortions of the video can be saved as presets and played back in sync with music for artistic effects.
This isn’t the first time Vactrols have made an appearance here, of course. We saw them a while back with this Arduinofied electric guitar, and more recently with a triple-555 timer synth.