Circuit Basics

There are multiple ways to represent a circuit. Last class we used a breadboard diagram to show how to arrange physical components in a breadboard. However, circuit schematics use a set of symbols to represent components in a circuit. When reading a schematic, note that the relationships between components are not necessarily spatial, they are laid out to best describe how to connect components, but not how to place them in physical space, or on a breadboard. Sparkfun has an excellent introduction to circuit schematics and symbols — read through it! Here are some of the basic symbols:

Some of you will find schematics easier to understand than the breadboard pictures, others prefer the more visual representation. For the purposes of this class you can use either method of representing a circuit, but you should be familiar with both. If you continue working with electronics, you will find that more complicated circuits often use schematics, as the spatial style can get super confusing as the components and connections pile up.

386 amplifier

Today we’ll work on a simple 286 amplifier circuit, perfect for boosting the gain on our hex schmitt synths and driving speakers. On top of everything you already have, you will need:

• 10k potentiometer
• 250 uF Capacitor
• 47nF capacitor (optional)
• 100 ohm resistor (optional)
• LM386 amp

Here are the two representations of the 286 circuit. See if you can put together a functioning amplifier from these diagrams…


Here it is in breadboard form:

And here is a hybrid representation, that uses symbols AND a spatial layout together:

and here is a nice page showing how to take a schematic and put it on a breadboard.