[ARC5] Diode Mystery

[Owner]

Wayne, i just reread this note and it appears to me my answer was a 
little hasty and there's more to the picture.
Altho scoping it would tell the truth.
If the meter reads 12 on one side and bonkers on the other, the mystery 
is a little more deep.
I would have to ask how much of a load the +12 output is under when you 
read the 30 whatevers at
the output post. If the  load is only the meter, or a very high value 
resistor, then yes i would guess there's
something tricky going on with the diode and the resistance and 
capacitance it sees.

This is one of those great questions that should be on some kind of 
proficiency test.
-Hue Miller


Sent: 11/30/2020 7:32:22 AM
Subject: [ARC5] Diode Mystery

>The other day I installed a rectifier diode in the 12VDC B+ line of a 
>radio for reverse current protection.  When I used my trusty Simpson 
>DVOM to check proper continuity I was shocked to see that the voltage 
>read something like 30VDC.  At first I thought that the output voltage 
>meter on the bench power supply I was using was wildly off, but 
>checking it at the output terminals showed that it was the correct 12V. 
>  But on the other side of the diode it read about 30VDC.
>
>I used a different DVOM and it read the proper voltage on both sides of 
>the diode.
>
>Anyone have any idea what could have happened here?  Is it possible the 
>diode created some noise that confused the Simpson DVOM?  If so, should 
>I be concerned about that noise getting into the radio?
>
>Thanks!
>
>Wayne
>WB5WSV
>
>
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