Electronics Development for Hobbyists and Students of Robotics

Resistors

Capacitors

Electronic Inductors

Inductors

Transistors

NASA Sojourner rover 8085 based computer

wirewrap breadboard with wirewrap tool

Electrical Engineering involves the application of electricity, electronics, and electromagnetism. Energy is available in various forms such as electrical, hydro, wind, and solar energy. An Electrical Engineer develops technologies to assist with the practical application of such energies. Electrical Engineers design components for electronic equipment, communications systems, power grids, batteries, motors, and more.

This page is intended to provide pointers to tools and software that can help with the engineering of electronic devices and electronic sensors. The software referenced here is all either free, inexpensive, or demo software so it can be tried without initially investing significant money. Where possible we've included a link to the site where you can get the latest version rather than a direct download of a possibly stale version.

Ohms law describes the motion of electrons through a circuit:

V = I * R

where:

V is the voltage between two points in the circuit
I is the current flowing through that part of the circuit
R is the resistance of that part of the circuit

The most fundamental electronic component is the resistor along with capacitors, inductors, and semiconductors including diodes and various types of transistors. While resistors resist the flow of any current, capacitors tend to resist the flow of constant current and inductors tend to resist the flow of variable current. Software tools that simulate the electronic circuitry you've created would allow you to test and debug the circuitry before building it. A common example of this type of application is SPICE (Simulation Program with Integrated Circuit Emphasis) which is an analog electronic circuit simulator.

The relationship of current and voltage with a capacitor in a circuit:

I = C * deltaV / deltaT

where:

I is the current flowing through that part of the circuit
deltaV / deltaT is the change in voltage over the change in time
C is the capacitance of that part of the circuit

The relationship of current and voltage with a inductor in a circuit:

V = L * deltaI / deltaT

where:

V is the voltage between two points in the circuit
deltaI / deltaT is the change in current over the change in time
L is the inductance of that part of the circuit

Electronic Circuit Simulation

Electronic Component Symbols

Electronic Elements supported by SPICE
SPICE letter code	element
B	FaAs field effect transistor - MESFET	semiconductor
C	capacitor	fundamental electronic component
D	diode	semiconductor
E	voltage controlled voltage source (VCVS)
F	current controlled current source (CCCS)
G	voltage controlled current source (VCCS)
H	current controlled voltage source (CCVS)
I	independent current source	power source
J	junction field effect transistor - JFET	semiconductor
K	coupled inductors
L	inductor	fundamental electronic component
M	MOS field effect transistor - MOSFET	semiconductor
Q	bipolar junction transistor - BJT	semiconductor
R	resistor	fundamental electronic component
V	independent voltage source	power source
X	sub circuit

Beyond fundamental analog electronic components there are electronic sensors (which often behave like a resistor or transistor), electro-mechanical devices that move mechanical things (solenoids and motors behave like inductors), and digital electronics (used to interface with or build digital computer processors and memory). Fundamental digital electronic components are the and-gate, or-gate, exclusive-or-gate, and not-gate.

Connecting these electronic components in a useful configuration produces an electronic circuit. Some common circuits include amplifiers used to increase weak sensor signals, H-bridges used to control current to motors, and analog to digital converters (ADCs) used to convert analog sensor signals to digital signals used by digital electronics and computers. These electronic circuits can be combined in ICs (integrated circuits) or on circuit boards. While it's unlikely that you'll be designing and manufacturing your own IC, once you have your electronic circuit designed you might want to build your own circuit board. Other helpful tools include applications that allow you to layout the placement of components on a circuit board and figure out how to route connections. If you design your own circuit board, you can fabricate it yourself or companies will fabricate a circuit board for you from your design.

When assembling circuits whether on solderless breadboard, or wirewrap breadboard, or soldering to printed circuit boards, you will need to know how to tell the characteristics of electronic components. For example, not all resistors have the same resistance. Most components have a code on them indicating what characteristics they have. In the case of resistors, they have a color code consisting of 3 or 4 colored stripes. The first two stripes indicate the first two significant figures of the resistance. The third stripe is the decimal multiplier. The value is given in ohms. If the fourth stripe exists, it indicates the tolerance. For example, a resistor with colored bands of brown, black, and red has the resistance of 1 0 * 10^2 or 1000 ohms, and a resistor with colored bands of red, red, and black has the resistance of 2 2 * 10^1 or 220 ohms.

Resistor Color Codes
color	significant figure	decimal multiplier	tolerance %
black	0	10^0 = 1	20
brown	1	10^1 = 10	1
red	2	10^2 = 100	2
orange	3	10^3 = 1000	3
yellow	4	10^4	4
green	5	10^5	5
blue	6	10^6	6
violet	7	10^7	7
gray	8	10^8	8
white	9	10^9	9
gold		10^-1 = 0.1	5
silver		10^-2 = 0.01	10
no color			20

In the case of capacitors, some will have their capacitance value written on them. However, ceramic disk capacitors have a three digit code. The first two digits indicate the first two significant figures of the capacitance. The third digit is the decimal multiplier. The value is given in picoFarads.

Some retailers for electronics and other parts are:

Electronic Circuit Simulation

Electronic circuit design and simulation tools

Link to LTspice
Link to PSPICE-FOR-TI
Link to TINA-TI
Link to SIMetrix/SIMPLIS
Link to MultiSim
Link to Orcadnote MicroSim and Orcad merged in January of 1998
Link to SapWin
Link to NGSPICE
Link to Quite Universal Circuit Simulator (Qucs)

Circuit Board Design

Circuit board layout, routing, and viewing tools

Download Protel Easytrax
File Size:	496 kb
File Type:	zip

Download File

for 16-bit Windows (should work on 32-bit Windows)

Link to Altium Designer

Link to Target 3001! discover

Link to LayoutEditor and FreeRouting

Link to DesignSpark PCB

Link to Pad2Pad

SimpCB auto router

Printed Circuit Board

The Gerber file format is the de facto standard used by printed circuit board (PCB) industry software to describe PCBs. Extended Gerber or RS-274X and Standard Gerber or RS-274-D are specific variants of the G-Code or RS-274 file format which is often used for numerical control (NC) of automated machine tools. Most PCB manufacturers will accept Extended Gerber or RS-274X files.

Link to Gerber file format which is used by most PCB manufacturers

PCB manufacturers

This page was previously hosted on geocities as www.geocities.com/rjkuhn_2000/hardware.htm. That old page has been copied and replicated in a number of other locations on the world wide web, but those other locations are snapshots and are not updated.