[sdiy] Diode Matching

Didier Leplae didierleplae at yahoo.com
Sat Apr 11 01:12:05 CEST 2020

I tried your suggestion. Over 5 minutes the reading changed from about 350mV to about 365mV. When I grab the diode with my fingers, it actually goes down a bit, just about 2mV. I tested this repeatedly with exactly the same result.
Incidentally, if I change the multimeter to read another diode, the reading stays at the elevated reading, 365mV. So that suggests to me that the meter is what's heating up, or causing the change, rather than the diode.
Throughout all this testing, I've been quite careful not to subject the diodes to temperature changes. I've got them taped to a notebook. The notebook is sitting by itself on a chair, not in my lap or anything. I've been working in a basement, so no big temperature changes or sunlight coming in to heat them up.

    On Friday, April 10, 2020, 05:14:22 PM EDT, Gordonjcp <gordonjcp at gjcp.net> wrote:  
 On Fri, Apr 10, 2020 at 08:44:28PM +0000, Didier Leplae via Synth-diy wrote:
> So far I have tried three different methods of testing and find the results to be confusing and unreliable.

Get a single 1N4148 diode.  Stick it in your meter in diode check mode.  Observe the reading.  Leave it for five minutes.  Observe that the reading has changed.  Squeeze the diode between your finger and thumb.  Notice that the reading changes wildly with the temperature.


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