how to......matching diode

[bent]

Hi,

i read several topic that people are matching diode in their circuit to get the better sound as possible....

but i don't know how to measure the diode to get a matching pair.....

so....how do we use a meter and what type of measure i look for to have a matching pair of diode??

thank's

bent

[Seljer]

If you're meter doesn't have that diode test thing set up can a circuit thats something like

+9v --------|10k resistor|----- |diode you are testing|>|-----gnd

and measure the voltage across the diode, that should be the forward voltage drop of the diode (though I believe it varies with the current going through the diode), which would be the thing you would be looking to match

[petemoore]

  I'm getting some more 3.88 DMMs for Xmas sendouts...
  These have the Diode checker [beep mode]  --->l--- setting. Set the DMM to diode picture, testing a good diode will show ____ [whatever it says when probes are lifted] when the diode is connected one way, and somehting like .6 when the diode is turned around, this is the Foreward Threshold Voltage, another of the same type may read .62 
  Test batche[s / pick some out which fall closest in the numbers to being 'match'.
  Most of the time these diodes will be placed in a circuit which applies a different voltage to one diode, less to the other, if symmetry of FVT is desired, not only the diodes need to be matched, so does the voltage each diode 'sees'. or...some other math's may apply...for two diodes to 'match' when they hit threshold in time, you need to consider
  diode #1's FVT
  diode #2's FVT
  The voltage applied to diode #1
  and..Voltage applied to #2
  If the diodes are in a back to back configuration from ground [like DIST+] or OA Clipper [TS] or anywhere else for that matter where *one diode is to react to the + Swing of the signal, the other [pointing *opposite] diode to do same to the _ swing, the circuit in questions voltage potentials during +/- signal swings isn't 'matched' anyway [unless you're super Lucky].
  I believe this is the basis of the 'null mod' on the Green Ringer, a poteniometer is used on one side so that 'offbalance left' / 'offbalance right' and 'balance/match/symmetry' can be adjusted to, by making it possible to vary the voltage applied to the diode clipping the - portion of the signal swing to be less than, the same as, and more than the other side [I randomly chose the - symbol, substitute the + signal if you want to sort that out, the point here is one side adjusts].
 

[bent]

ok,
so i took out my meter...i"m lucky i have a diode test mode....

so i took a couple of 1n914 and mesure....

i have 597 , 602, 604, 598 , ect....

so i just have to find 2 of the same mesure....right?

Cool....now i can match them....

thank you very mutch .....

bent

[bent]

in the same "patern"...

this is my meter...
http://www.multimeterwarehouse.com/dt830bf.htm

i see that i can test transistor....

i test few 2N5088, and i get some reading like 487 , 502, 490, ect... in a circuit like the Ross compressor (5 transistor 2N5088) , will it sound better if i find some 2N5088 that have the closest "reading" or it don't change nothing in the sound....

bent

[Paul Perry (Frostwave)]

There aren't many places where I would expect matched diodes to matter, but of course it is up to the ears of the builder.
In fact, the only one I can think of, is Ken Stone's transformer style ring modulator.. you need extreme matching there to get the carrier rejected. Matching for that one, you need to work in still air, wearing gloves (or taking other precautions) so the diodes don't change in temperature as you touch them.