Hello,
Just got an Oscope and was trying to measure some inductors using the ringing frequency technique. Despite trying various values of caps and sizes of inductors, I'm unable to get the tank circuit to ring.
I think I have several issues working against me. Just thought I would see if some of you might have some helpful input.
Here are my ideas for why the test isn't working:
1. My pulse gen doesn't have a fast enough rise time. The best I've come up with so far is to program a PIC with a pulse. This only gives me a rise time of 36nS. Is the slow speed of my pulse washing out the ring?
2. The output current of the PIC is only about 20mA. Is this low amperage not sufficient to saturate the cap, inductor, or both therefore not giving the tank enough energy to ring?
I have plans to build the pulse gen discussed by W2AEW with the 74ac16 which will give me a faster edge. It will only be a slight increase in current, however.
I know there are other ways to measure inductance with an Oscope, but most/all of them require a precision function gen. I just got the scope so that will be down the road a bit. Also, the frequencies I would need to test the inductors I'm using would make the function gen cost more than my scope.
I also know that my measurement of inductors really isn't that important. Just a learning experiment.
Thanks.