Everything for Electronics

Jim Stewart

Jim's Articles

Build an Inverting DC-DC Converter
January 2013
Ever need negative voltage when all you can get is positive? This voltage mirror device will give you -V out when you put +V in, and works over a range of voltages without adjustment.

Build the Voltage Mirror
August 2012
A glass mirror gives an exact copy of an image but with left and right swapped. A voltage mirror gives a copy of the input voltage but with the polarity swapped.

You’ll Flip Over This Coin Toss Circuit
June 2009
Exclusive Online Article: It’s Friday night and you’re hungry, so you decide to go pick up some food. Maybe a pizza, or maybe some kungpao chicken. You love them both, but you must choose one or the other. Do you flip a coin? Sure! But now, you can do it electronically! Let’s build a coin toss circuit!

Wind Your Own Transformers and Build a DC-to-DC Converter
March 2009
Use this board as a platform for your switch-mode projects and experiment with winding transformers.

Build A Voice Changer
May 2008
Build this voice changer circuit to make your voice sound like a Dalek from Dr Who.

Build A Switching Regulator
June 2008
We’re all familiar with linear IC regulators, especially the three-pin TO-220 package types like the 7805 and the LM317. They’re inexpensive, and their low-noise andfast transient response make them ideal for many applications. Their one drawback is efficiency. For example, a 7805 regulator delivering one amp from an input of 12 volts will dissipate seven watts of heat while delivering five watts to the load. Plus, a large heatsink would be required to keep it cool enough to operate...

Use Surace-Mount Devices To Build An FM Transmitter
September 2008
In this article, we will construct a low-power FM transmitter that can be received with a standard FM radio. Along the way, we will look at how varactor diodes work and how to use an inductor that's in the circuit board.

Temperature Gauge Project
October 2008
We will build a temperature gauge for the range 0°C to 50°C using a thermistor in an analog circuit. Why use a thermistor? Two words: temperature transducers. Along the way, we will look at various ideas such as how to linearize a thermistor, the effect of thermistor self-heating, and zero and span adjust in a gauge...

The Big Ear
December 2008
Ever wish you could build an "audio telescope" that would let you hear things that were faint or far away? Well, this article shows you how to build such a thing. We call it the Big Ear.

The Proto Buddy
January 2009
Take proto circuit building to the next level with this device that allows you to expand your existing board so you can create all kinds of circuits.