I recently bought a little LC meter on EBay. It was like $10.
When I got it, I immediately made a variable capacitor out of some aluminum foil, cardboard, and a piece of plastic so I could measure it. Great fun.
Not long after, I was building the Mighty Mite, and thought "hey, here is a coil! I should measure it!"
I thought maybe it was out of range, or there was some other reason it wouldn't measure. But, it could also be that it just wasn't working for inductance.
So I decided to build a meter to compare with.
I didn't want to spend a lot of time reinventing any wheels, so I cast around for a design someone had already made. There are quite a few out there, but I wanted to focus on quick and simple, and found this.
His page explains how it works really well. Basically it is an LC tank formed between a known capacitance and your unknown coil. It uses a comparator that I luckily happened to have in my junkbox. I didn't have the 1uF caps, but I had some 0.47uF that I put in parallel. My LC meter says that all together they equal 2uF, which is exactly what I needed.
I wound some wire on a pill bottle to have something to measure. I calculated that it should have an inductance of 31.1uH. The Arduino measured it as 45.59uH. The EBay device measured it as 0.
Someone on the QRP-Tech Yahoo Group was asking about who had what LC Meters. I mentioned I had this one that only measured capacitance.
A nice man by the name of Steve wrote me to ask if I shorted the leads when I first go to measure the inductance, as it requires that. Um... no. No I did not. Now, to my credit, it didn't come with instructions and that isn't intuitive. In any case, now that I know how to actually use it, it seems to work.
All in all, though, I'm glad I had the issue, because it gave me an excuse to wire up this project!