Project: The Ubiquitous Xstr Checker

Thread Starter


Joined Aug 8, 2005
Since transistor amplifiers and other xstr circuits are still viable options for the hobbyist, I've attached a schematic for a bipolar transistor checker. This was published in Popular Electronics back in the mid-1970's, and has made it's rounds ever since (you can find it elsewhere on the net). There are certainly more complicated versions that can accomplish the same or better results. But, for anyone looking for a rather simple project, this one can come in handy. Note that although it should work "in-circuit" you may want to first remove the xstr to be tested from the board in order to be more confident of the results.

This can be made on a rather small PCB or perf board, and placed into a box not much larger than a pack of cigarettes. The BCE connections can be done with mini-clips attached to ~6" of wire each, labeled accordingly, that clip onto the respective leads of a xstr to be tested. The switch S1 is a normally-open, momentary, type so the unit will not remain powered and deplete the battery.