Why is Diode Barrier potential not measurable by Volt meter?

[barath_87]

Diode Drop

Why is the Diode Barrier potential not measurable with Volt meter?

<I know that Some Multimeters have a provision to measure the diode drop. My doubt is why is the potential not measurable directly?>

 

[IanP]

Re: Diode Drop

A diode is not a voltage source - it does not generate voltage by itself ..
A voltmeter, on the other hand, only measures voltages generated by voltage sources such as batteries, power supplies etc. etc. ..
Apply current to a diode (voltage source + series resistor) and then measure voltage accross it ..

Regards,
IanP

 

[amriths04]

Re: Diode Drop

thats because once you put in the multimeter or the voltmeter terminal across the diodes it will source in a current which is possible only if the potential barrier is broken. hence you may not be able to measure it. this is my opinion.

 

[IBO]

Re: Diode Drop

having a barrier voltage doesn''t mean that u should have a meter reading.
No current is flowing through diode contacts. This is not device level measurements.

 

[melc]

Re: Diode Drop

Why is the Diode Barrier potential not measurable with Volt meter?

<I know that Some Multimeters have a provision to measure the diode drop. My doubt is why is the potential not measurable directly?>

Use a multimeter which have a diode symbol. That one will inject around 1 miliamper and measure the voltage as well.

BTW, how could you detect easily differences between a germanium diode and a schottky diode as long both have the same voltage drop across them at a given current of say 10mA ?

50 shit points REWARD for a right answer!

 

[ALERTLINKS]

BTW, how could you detect easily differences between a germanium diode and a schottky diode as long both have the same voltage drop across them at a given current of say 10mA ?

50 shit points REWARD for a right answer!

While checking with multimeter, touch diode with hot iron. If germanium, voltage drop will decrese more rapidly than shottky. Awnser after 4 years is just for reference.

 

[betwixt]

Well done @ALERTLINKS.
But I think you might need your hat to deal with those 50 'special' points :lol:

Brian.