At first glance you might think building a robot will require a deep understanding of electronics but it actually relies on a lot of the electronics we need being self contained in little chips on a circuit board.  All we really need to do in robotics is to connect the chip’s pins to the right inputs and outputs in order to make the robot do what we want it to.  Sometimes, however, we can’t simply connect things together or we’ll destroy a chip and often it helps to know the function of each chip in order to better diagnose what might go wrong with the robot during a competition.

Let’s begin with the basic notion of a circuit.  A circuit describes the condition where electric current (remember that current is the flow of electrons) flows from a source, through the devices in the circuit and returns to the source’s other pole.  This seems pretty intuitive but it’s important to understand that you can’t do much with current that goes to something but you can do a lot when it flows through it and into a ground.

Discrete components

Resistors

  • Unit of measure: Ohms
  • Types: Surface Mount, carbon, foil.
  • What they do: change the ratio of voltage to current in a circuit
  • Symbol resistor
  • what they look like

resistors

From top to bottom

Surface mount, DIP chip, carbon, foil, precision foil

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Capacitors

  • Unit of measure: Farads (although its usually microfarads or picofarads)
  • Types: surface mount, ceramic, tantalum, poly, electrolytic
  • What they do: They’re little reservoirs that can hold a finite amount of electricity.
  • Symbol:cap
  • What they look like

capacitors

In order from left to right

Ceramic, tantalum, poly, Electrolytic (I’m out of surface mount caps but they look just like the surface mount resistors).

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Diodes

  • Unit of measure: Two numbers.  The high voltage is the reverse voltage limit that will fry your diode and the small voltage is the voltage drop from the anode to the cathode.
  • Types: Zener, Schottky,  Light emitting, rectifier, thyristor
  • What they do:  Basically they’re a one-way valve for electricity.  They’re most often used to flatten a sign wave or oscillating current.
  • Symbol: diode
  • What they look like

diodes

From top to bottom:

Surface mount, Zener, rectifying

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Transistors

  • Unit of measure: Max voltage between the emitter and the collector, current gain to the emitter (called the beta),
  • Types: surface mount, NPN, PNP, Darllington, Field Effect, etc.
  • What they do: most people use them as a switch but they actually act as a current amplifier.
  • Symbol: transistor
  • What they look like

transistors

From left to right:  These are all NPN transistors of increasing power.

Surface mount, TO-92 package, TO-220 package, TO-3 package

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Crystals

  • Units of measure: Cycles per second or Hertz (1 Hz=1 cycle per second)
  • Types: crystal, crystal with cap included
  • What they do:  These are the “Pulse” of the microcontroller we spoke about in the 4th blog but they’re also used in R/C in order to establish the radio frequency you’ll be using to control your robot.
  • Symbol: crystal
  • What they look like:

crystals

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Want to know more

This about the coolest way I know to learn basic electronics: http://www.falstad.com/circuit/e-index.html

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