Here that same tester on Aliexpress since the eBay link to it was sold out

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And this tester can test many TTL/CMOS IC's, triodes, leds, plus zeners (these less exact though), opamps and some audio amplifier IC's. And the optocouplers!:
https://www.ebay.ie/itm/IC-Tester-Meter-Transistor-Maintenance-Tester-Detect-MOS-PNP-Op-amp-optocoupler-/153346158391

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Here a new tester I just found online that also tests the pwm uc3843 ICs : http://pwm.company/uc3843-series-ic-chip-tester-pwml-test3843-diy

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Gassan: yes, there is one by Jestine on this web site. it is an excellent book about SMPS..I recommend it. have a blessed day

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The problem with abbreviations Robert is that we never for certain know what they mean and they only cause more confusion in case we doubt. Why I hate those short naming conventions. Also because they can mean many more things. I neither ever have heard about people I know of naming it a PPSR before and I very much doubt that anyone knows about what it means. You are probably the only one 'I know' of using it? By-the-way: I still don't know what it means. Programmable Precision Serial Resistor? Just writing 'Programmable zener' is not that hard and fully covers it.

In case someone needs the info on making the testers. Here some links:
https://www.youtube.com/watch?v=jbbl3vQ2E7A
https://www.youtube.com/watch?v=zlChCkYzY8E

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It doesn't seem fair to call the programmable precision shunt regulator a zener since it has better characteristics than a zener. I think that many people do that because they don't like to type that long name. We need to get everybody to call it a, "PPSR" instead. That is easier to type!

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