Whether a student or an instructor in an electronics lab, having the means to check the operation of a bipolar junction transistor (BJT) at the proto-board stage is a blessing. Most students do not have the experience or knowledge that it takes to recognize whether or not a BJT is operating. With this handy BJT checker, a student or the instructor can simply remove the component from the proto-board, insert the component in the BJT checker, push the press-to-test button, and observe the BJT checker's LEDs (light emitting diodes). (Contains 3 figures.)