While resistors and capacitors are easily procured and stocked, most RF circuits require inductors in a wide range of very specific values. In most cases, you need to create these yourself. Here are the principles behind inductance and some tricks that I’ve used to make my own inductors.
Much as we learn about ourselves from our mistakes, we can learn a great deal about transformers from their imperfections.
The digitally-programmable potentiometer (DPP) is a mixed signal, system-level control device performing a component-level function. The potentiometer adds variability to the analog circuit, while the digital controls add programmability. The DPP brings the high speed, programming, computation, and control of a processor to the variation of the potentiometer in a wide array of analog applications.
Internal resistance within capacitors — known as Equivalent Series Resistance — can increase over time, causing power loss and/or heating. With this device, you can test your stash of capacitors so you can weed out any bad ones before you install them in your projects.
Whether you need to flash an LED, energize a relay, turn a buzzer or alarm on or off, or invert a voltage level, the NPN transistor switch can easily solve your problem. This article shows you how to use a transistor as a simple SPST switch.
Every signal begins with an oscillator — In ham radio, the oscillator is a key element in generating signals, mixing them together, and extracting the information from them. Let's see how to make an audio oscillator, plus learn about common RF types.
Previously, we learned what makes an oscillator do what it does, and tried a simple low frequency example. Now, it's time to move up — in frequency — to the oscillators which make the signals that drive the ham's wireless world.