[Day 2] Printed Circuit Board design for beginners


#1

Summary

  • When designing eletronic circuits, start simple. Use parts that are easily available and easy to work with (maybe later they will have to be replaced, but that is ok, since you’ll already have a better understanding of your circuit).
  • Using a repository to see what parts are available is a good idea, Octopart is one example.
  • All electronic parts have a datasheet, and in there you’ll find a lot of information about the part. They normally contain information concerning how the parts should be operated (maximum voltage and current, if the part has a polarity, what and how it outputs information). They also contain example circuits of how they should be connected in a circuit (which pin should be connected where, and what other parts need to be placed together for optimal function).
  • Digital electronics designs are the most commonly used by makers/hackers because they are simpler to understand and to get started with:
    • Electricity always flows in one direction VCC to GND
    • Circuits usually flow in a certain way: sensor → electronic brain → actuator
      How to hook up chips to make them do what you want

Notes

How to make things as fast as easy as possible (no annoying details)

(People who participated in the session: I didn’t understand some of the names and projects because of the noise of the two sessions running in the same room, please add here!)
Introduction, name and how can electronics help you
Kaspar (giving the workshop)
Justin:
Krismucha: temperature controller
Fernan:
Aga: Turn surfaces into an interactive surfaces
Ananda: wants to understand how synthesizers work (touch input, sound output)
Pollock: AC motor controllers and charge controllers
Julieta: air quality monitoring project, the sensors could be improved. Automatic cat feeder
Pierre: interested in the methodology for teaching PCBs
Minerva:
JP: Make a button controlled led display
Andre: amplify a signal using transistors
Shubi: something with sound and light to decorate room
:

General examples:
Inputs – read and notice things: sound, temperature, buttons, light levels
Octopart as a good resource for learning different sensors. The website has nice search engine, and it is categorized.

Outputs: Speaker, heater, LED lights, motor

In between input and output, you normally use an arduino or some other processing unit, so that you can calculate things, route signals, and tell the actuators when to do something. There are several different options, choose the one that is the easiest for you to start with. (do you have a friend that can program Raspberry pis? Use that. Do you know how to use PIC controllers, use that then).

Question: how do you know what kind of sensors to use?
Cat food example with a light sensor – There are light resistors, Opto couples, photodiodes

suggestion: make one circuit together the chicken coup temperature sensor/light controller.

Choose a sensor using octopart, just “anyone” to start with, maybe try to look for something with the smaller number of connectors and watch out for their format, SMD or Through hole.

Make sure you write down the components you are choosing and using, this is generating a bill of materials. It is easier to do it incrementally and interactively then to have to write down dozend of components at once.

Electronic components need to be powered up. When designing DC circuits, power runs form + (VCC, 5V, 3V3, 1V8) to - (GND)

Manufacturers release their sensors and actuators with datasheets – a document describing with enormous details about the components. The trick is to run through them without reading everything and extract the information you are concerned with. Pointers of important things: “maximum ratings” - Limits of what your components are able to take, you shouldn’t run your devices using these values, but rather something smaller then them. (if a device runs maximally with a 35V power suppy, you should not run it constantly with a 35V supply. 20-30V are good values).

There just a few different ways to hook up digital electronics:
UART:

  • TX
  • RX
  • Baud rate
    SPI
    -MOSI (master out, slave in)
    -MISO (master in, slave out)
    -Clock
    analog output: a variable voltage signal that translates into a certain quantity the component is sensing
    analog input

In the chicken coup example:

We selected a temperature sensor with three pins, VCC, GND and analog out. This is then hooked up to the arduino pins: 5v, gnd and analog in respectively. Or (vcc → 5V, GND → GND, Analog out → analog in A0).