Do you remember my impromptu experiment on Sunday where I tried to get an LED to light up without exploding? I only managed it once, but that was all the encouragement I needed to begin wondering whether I could add an LED to my Piezo Buffer circuit.
My biggest fear was that I would break my Piezo Buffer circuit in the process. With shaking fingers I made the required adjustments and what do you know, the bloody thing worked! Ha ha. I was bouncing off the walls with happiness!
That was until I started experimenting with different resistors and everything went dead on me. DAMN! What on earth had I done?
What happened next was hour after hour of debugging. Try as I might I couldn't find a fault. Eventually the penny dropped... perhaps one of my components was broken. I'd destroyed the JFET on earlier attempts. Surely this was the most likely one to have been broken. But how could I test it? Read on...
My moment of revelation came from watching Stan Gibilisco's fantastic video above where he explains how to test a JFET. I love Stan's accent - he certainly is an engaging speaker... and he knows his beans.
Having watched this video I picked up just enough information to set me off on my own experiment. At the end I looped back round and I can see now that Stan was right all along. ;-)
Watch the video for the "proper" explanation. I'm going to run through what I did just so you can see how to do this for yourself.
Before I go too much further let me tell you that as part of my research this week I've discovered that you can buy component testers. The one pictured above is available on ebay as a kit. I've ordered one. I don't know how good devices like this are, but what a great idea!
In theory, it can be used to test JFETs and all manner of other components. I'll report back on this some time in the future.
Let's stick with the long-handed way of testing JFETs for now...
And there you have it... a fairly painless way to test JFETs. What worries me now is how easy it has been for me to destroy 3 JFETs. I've only got 2 left. Maybe I should build my buffer quickly before I blow these too? :-O