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| Reading measuring testing diodes |
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| wertyu:
My new multimeter seems to measure diodes both ways 0.6 , my fluke does not on same diode . also the fluke measures the diode in ohms but the isotech does not . any ideas on why i like the diode test it simple this has confused me . |
| wertyu:
i think it might be reading it as a negative 0.6v ? bit confusing i prefer the OL . |
| wertyu:
is there a way to purposely damaged a diode so i can see the results on this meter ? manual seems to suggest it tests in both directions and tell you if P / N connected and if its faulty it will OL ? |
| Audioguru:
Your new meter has many mistakes in its design. 1) It should use a low voltage for measuring ohms so that it does not forward bias a semiconductor diode or transistor. My Fluke uses 200mV. 2) When testing diodes it properly shows its forward voltage but the polarity is very confusing. It does not show if a diode or junction is shorted or is leaking. My Fluke shows a forward voltage when forward biased and shows OL when reverse biased and is not leaking. |
| alsetalokin4017:
I agree, that diode "measurement" is screwy. The top left illustration presumably shows a correct measurement of the diode's forward voltage drop Vf. The bottom illustration is whacky--- connect diodes in antiparallel like that and if both are good, once again one should only read the Vf of the forward-biased diode. The top right illustration makes no sense whatsoever. If a diode is good it should not conduct in the reverse biased direction, to a first approximation. So how, if the meter just magically flips polarity and reads the forward voltage anyway, how are you supposed to tell if it blocks in the reverse direction properly ... I don't get it. How to damage a diode? That's new-- usually we want to know how to -Not- damage them. They usually fail open, or shorted, in my experience. Easy enough to do by overvolting in reverse or overcurrenting in forward biasing. What this meter will read when it is confronted with an open or shorted diode, or just a leaky one, is an empirical question. Let's do it! :bullshit: |
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