Welcome to my coils page. Coils are very important in radios. All radios have them. They, along with other components determine what station a radio is tuned to.
Coils or inductors are one of my favorite subject to write about because they are so easy to build. Try building a variable capacitor and you will see what I mean. My personal favorite type of coil is the spider form coil. They are easy to wind and adjust.
Besides the coil former, there is the coil type. For main tuning tank coils, especially in crystal radios, I like the contra coil. They just give a bigger bang for the buck. There are extra considerations to watch out for when designing and building them. I hope that these pages will assist you in building the best radio that you are able.
The coils that I show on these pages are made from litz wire. This is a special type of manufacturered wire that is designed to lower your coil losses. My designs can be ported to standard insulated magnet wire.
I have some practical examples of coils that are useful in radio building. I have cylinder, spider, variocoupler, and variometer examples. I have variation on coils called contracoils.
Contra Coils (cylinder and spider)
Cylinder Coils Coils wound on cylindrical forms. This is the most popular coil style.