Zener Diodes Voltage Drop

[claytushaywood]

I measured the forward voltage drop on some 1n4729 3.6v zener diodes I got from tayda.  I'm getting between .5v and .75v and I found a data sheet that says the forward voltage drop should be 1.2v for these.

I'm building a clone of the death by audio robot (uses ht8950 chip) should I try to get some that measure 1.2v forward drop or does it really matter?

thanks!

[chromesphere]

Ill have a go at this question before the more knowledgeable folk chime in.  The 1n4728 is a silicon diode.  Generally silicon diodes have a 0.6v drop when measured with a multimeter.  Germanium diodes are around 0.3v, and led's are anywhere 1v+.  I think perhaps the datasheet has different conditions when testing the diode then what we do (a multimeter).  The datasheet says "IF = 200ma" when testing the forward voltage drop and I would doubt that would be the same current the diode tester on your multimeter would be using to measure Vf.
Paul

[jubal81]

Best thing to do is tack solder a couple wires to the PCB and stick them in a breadboard. Try them out - try out others. That way you're not second guessing your self later on.

[claytushaywood]

so measuring the forward voltage drop is not gonna give you the voltage of a zener diode.  the 1n4729 is labeled as a 3.6v zener diode when I do a google search- the circuit calls for a 3.6v zener diode.  do I really need to run wires to a breadboard to see if my 1n4729's are dropping the correct voltage?

[jubal81]

Sorry, I misunderstood. Thought you were asking about using them as clipping diodes. If it's the right part No., then it's fine for that application.

If you want to test it, put a small resistor between 9v and the cathode, with the anode to ground and measure the DC voltage difference cathode to anode.