Electronic circuits

This page includes general tips on building electronic circuits.

Components

Solderless breadboards

Solderless breadboards allow us to make circuits allowing easy replacement of parts and very quick connections, but require adapters for surface mount devices. They're great for children and anyone who wants to avoid melting heavy metals or tedious wire-wrapping posts. Boards usually come with short busses to connect components to each other, and long busses to carry the two voltages of the power supply. See the wikipedia article for an inside look: https://en.wikipedia.org/wiki/Solderless_breadboard

Care must be taken when putting components in solderless breadboards, since they meet resistance from the clamping buss that is just tight enough to hold the pieces securely while at the same time allowing them to be removed by force. Without practice, it is easy to bend wires and pins you are trying to insert into the breadboard. When placing the many pins of integrated circuits at once, it is best to use a special chip-inserter that keeps every pin in line. Likewise, when removing ICs, it is best to use a chip-puller that grasps the opposite ends of the chip and pulls evenly so that pins don't get bent for being the last to come out.

Solderless breadboards always come with slots spaced at 0.1". Components don't always have leads with this spacing, however, and care must be taken to bend the leads so that they do fit—Too much bending and the metal breaks.

Components for solderless breadboards

Headers are sets of pins on a structure that makes them easy to place onto and remove from breadboards. You can solder components or wires to these headers for easier insertion into breadboards, or you can crimp terminals onto wires and put them in wire-housings that mate with the headers.

Jumpers are wires with ends bent at 90º and with a length some multiple of 0.1", made to jump from one buss to another on the breadboard. They are conveniently color-coded by length, where no insulation jumps 0.1", red insulation jumps 0.2", orange 0.3", yellow 0.4", green 0.5", blue 0.6", purple 0.7", grey 0.8", white 0.9", brown 1.0", red 2.0", orange 3.0", yellow 4.0", and green 5.0". To some it is a pleasure and a skill to make a complicated circuit on a breadboard with a minimum of custom bends and lengths of jumpers, while to others quick completion trumps neatness and a frazzled board that works just as well is just as good as a neat one.

Micro-controllers

The following are micro-controllers I've programmed.

• PICAXE chips allow easy programming in BASIC on Mac/Linux/Windows, with a free compiler from Rev-Ed.
• 8051 is a long-standing set of chips. I bought a programmer from the now-defunct Iguana Labs that works with Windows and Linux. I learned assembly language to program these. See Bicycle speedometer.
• Arduino is an open-source hardware and software platform from Italy with a dozen variations, programmed in C with free software. One usually buys a printed circuit-board with power supply, communications ports, a switch, a crystal, and the micro-controller itself, with easy-to-connect pins for easy connections to solderless breadboards, or extensions called "shields." http://arduino.cc
• PIC is a robust, inexpensive micro-controller that comes in many variations and sizes, from Microchip. http://www.microchip.com/pagehandler/en-us/products/picmicrocontrollers
• AVR is another robust, inexpensive micro-controller from Atmel, with various capabilities sometimes including USB. http://www.atmel.com/products/microcontrollers/avr/default.aspx

Capacitors

I only recently discovered how simple it is to identify the capacitance of small capacitors, there being a code similar to the resistor code, but in picoFarads. Thus, if I see 102 on a capacitor, I know that the capacitance is 1.0 nanoFarad.

There are many different types of capacitors that are not always interchangeable, including ceramic, tantalum, foil, electrolytic. Some are polarized, meant to be placed with one side to be kept at a higher voltage than the other.

Rechargeable batteries

Rechargeable NiMH 9 volt batteries are great for experimenting.

See also

See Circuits for teaching physics for a discussion on how building circuits may be beneficial for students of physics beyond just learning about circuitry.

See my electronic parts wish list.