HP HP-Bench-Briefs-1974-09-10 free download

File name HP-Bench-Briefs-1974-09-10.pdf

P L l C SERVICE INFORMATION FROM HEWLETT-PACKARD SEPTEMBER-OCTOBER 1974 # ! ALL ABOUT DIODES `I by George Stanley Diodes may seem simple to you as they have just two leads, but do you know how to recognize and test the following: PN, Zener, Ava- lanche, SRD, Tunnel and PIN. In Order to keep the number manage- able I'm leaving out light-emitting, four-layer, and microwave mixer diodes. forward and reverse conductance. PN Diodes That is, it should show a high resis- tance when the diode is reversed somewhat when you change scales Let's take the most basic first: the biased and a low resistance when common, garden-variety PN junc- or use a different ohmmeter. The it is forward biased. You might . ..-t ion diode. This is man's attempt to make a one-way switch. That is, ideally, no current would flow wonder why the readings change reason is because the diode curve is non linear. It's like changing from operating point "A' to when the device is reversed biased operating point "B" in Figure 2. and there would be no resistance A more interesting way to test when it is forward biased. Figure 1 diodes is to display the V-l charac- shows the ideal. teristic (Figure 2) on an oscillo- scope. This can be done using the tester of Figure 3 which we will use again in a future article on testing transistors.