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Identifying ADALP2000 marking for zener 1N4735 and small signal diode 1N3064

I find it VERY difficult and frustrating that the parts for some of the diodes in the AALP2000 kit come together taped and there is no real way to identify which one is which.  If I zoom in the each part I read

PH C3V6    on one of the diodes and  ON J2 0 307 on the other

Which one is the zener 1N4735 and which one is the small signal diode 1N3064?

I Googled it and there wasnt a clear description of what these labels represent!

[edited by: lallison at 3:26 PM (GMT -4) on 15 Aug 2022]
  • Unfortunately markings can vary from manufacturer to manufacturer, and it looks like there was a misprint on the ADALM cover. The wiki page:

    did note that the Zener diode could be either 3.6V or 6.2V, but still wasn't 100% clear. Just added some clarification, as well as a simple circuit to identify what's what.

    But I'd guess that your diode labeled PH C3V6 is the 3.6V Zener, that's what is in my kit (and verified with the test circuit.)


  • C3V6  is the code from Zetex for their 3.6 V  (a little bit like  4K7  is for 4.7 kilo ohm) Zener diode. The first two letters are probably for the format of the component.

  • PH C3V6 is the marking on my diode from the kit as well. Although you would think the 3V6 indicates a 3.6V zener, the test current (Izt) for a 3.6V zener is 69 mA. When I put 66 mA through the part, I get 4.4V out of it, so it's not a 3.6V zener. The closest I can figure is that it's a 4.3V zener. The test current for a 4.3V zener is 58 mA. When I put 56 mA through the part, I get 4.4V which is consistent with a 4.3V zener. That would make the part a 1N4731. This is all pretty bizarre. It's either frustrating or it makes for an interesting “reverse engineering” project.

  • While it is not a standard, as far as I know, it is common to define VGS(TH) for a Mosfet and Vz for a Zener diode as the voltage to get 1 mA  (in the reverse direction for a Zener). Low voltage Zener diode are not known to have a near vertical slope.

  • The Vishay datasheet lists two test currents Izt1 and Izt2. Izt1 is the 69 mA you point out but Izt2 is 1 mA for diodes from 3.3 V up to 6.8 V. The Vz (nominal) listed is for Izt1 but the datasheet does not say what Vz is for Izt2 for some reason? Why have a test condition like Izt2 and not provide a voltage value under those conditions?

    The spec table does list a resistance value of 10 ohms. A simple back of the envelope calculation for 69 mA Iz would add 690 mV to the voltage at 1 mA Iz or if we assume 3.6 (at 1 mA) + 0.69 = 4.29 V.