Posted on by Tom Zicarelli

Varactors

Voltage controlled variable capacitors

Also called varicaps. They are diodes operated in a reverse bias condition. As voltage increases the capacitance decreases.

Read this first

Tutorial by Phillip Atchely, KO6BB http://www.qsl.net/ko6bb/varactor.html

More tutorials

Using Varactors by Stefan Hollos and Richard Hollos: http://www.exstrom.com/journal/varac/varac.pdf

Tutorial by Ian Poole at Radio-Electronics http://www.radio-electronics.com/info/data/semicond/varactor-varicap-diodes/basics-tutorial.php 

Another tutorial from Radio-Electronics?: http://www.radio-electronics.com/info/data/semicond/varactor-varicap-diodes/circuits.php

Threads from The RadioBoard Forum:

Varactor tuned regenerative radio by Tony G4WIF “The Two Dollar Regen” : http://www.cqham.ru/forum/attachment.ph … ntid=28430 More information here: http://theradioboard.com/rb/viewtopic.php?t=3568