Just a diode

If it is in the dark, zero.

True if a perfect voltmeter, but most likely you'll see a little leakage current and hence a small voltage.

Are you claiming that a diode produces power (pushes current with a self generated potential drop)?

Small signal diodes can rectify stray RF and AC fields that are picked up on the test leads.

But to rectify the effect..... dont the stray Rf signals be greater than .6 V [ for Si ] ???

Nope. The nonlinearity of the i-v curve creates a partially rectified (and therefore non-zero) dc signal. Try it yourself. (Use individual leads, not coax.)

Mark

If you have the meter set to measure volts, zero. If you have the meter set to measure current, zero. If you have the meter set to diode test, you'll see the forward voltage drop across the diode for whatever current the meter puts out at diode test, usually something on the order of a milliamp. Assuming you have the leads' polarity correct. Something around six tenths of a volt give or take a tenth, but of course it depends on the particular diode and the current the meter delivers through it.

most of the time nothing at all, but if you can shine some (considerable amount of) light on the junction you'll see the photovoltaic effect in action.

Try a glass-encapsulated diode (1n914, 1n4148) and use a magnifying glass to focus sunlight. it shoulde register on any halfway decent milivoltmeter.

it works with LEDs too.

Bye. Jasen

No. He's claiming a voltage picked up by the test-leads (Hence the word "Sensitive Voltmeter") due to RF and AC signals in the air.

Peter

And how is light of influence to RF/AC signals when not put into the context of Quantum Physics? ;)

Peter.

But then, it is not in the "dark". ;-)

Johnson noise, too.

John

No, of course not. But the best voltmeters made still have picoamps of leakage and this will generate a voltage. Also thermal mismatches will generate enough current to show a voltage across the diode. If sensitive is defined to be ZERO input current and isothermal leads, then the diode will read zero in the dark.

What is the answer if you are trying to not confuse a beginner?