There’s a famous old story about [Charles Steinmetz] fixing a generator for [Henry Ford]. He charged a lot of money for putting a chalk X in the spot that needed repair. When [Ford] asked for an itemization, the bill read $1 for the chalk, and the balance for knowing where to draw the X. With today’s PCB layout tools, it seems easy to put components down on a board. But, as [Kasyan TV] points out in the video below, you still have to know where to put them.
The subject components are inductors, which are particularly picky about placement, especially if you have multiple inductors. After all, inductors affect one another — that’s how transformers work. So there are definite rules about good and bad ways to put a few inductors on a board.
However, in the video, air-core coils go through several orientations to see which configuration has the most and least interference. Using a ferrite core showed similar results. The final examples use toroids and shielded inductors.
One reason ferrite toroids are popular in radio designs is that coils made this way are largely self-shielding. This makes placement easier and means you don’t need metal “cans” to shield the inductors. How much do they shield? The orientation makes a little difference, but not by much. It is more important to give them a little space between the coils. Shields work, too, but note that they also change the inductance value.
While we like the idea of grabbing a breadboard and a scope to measure things, we want to point out that you can also simulate. If you didn’t understand the title, you probably don’t listen to Propellerheads.
