measuring capacitance and inductance

[nhoj]

measuring capacitance

hi to everyone,

i wonder where should i put this topic...

anyway, just want to ask... how do we measure capacitance or inductance???

i mean, there are already LCR meter, also other DMM has now the ability to

measure capacitance and inductance, but i just want to know how these

measurements done...

for example, how does a DMM do it??? what it does to measure cap and ind...

any ideas, facts or opinion are very much appreciated here.... i just really need it

badly... tnx

 

[heyheyhey]

hay bridge method of measuring capacitance

Here is how Agilent makes that measurement
http://www.home.agilent.com/agilent...c=eng&ckey=1256668&nid=-11143.0.00&id=1256668

You can also input a square wave and use the output to calculate the impedance.

 

[grey4]

microcontroller measuring capacitance

All measurements are done indirectly; let say that one can calculate inductance taking into account turns, diameter of coil, space between turns, layers and for capacitor the area of plates and the distance and matter between them; those are difficult and theoretical.

Better is to measure the effect done or appening using them and for that there are several "methods" depending of the accuracy nedeed.

One method is to put, let say, the component to be measured (cap or inductance) in a oscillating circuit where the unknow component is paralleled with know one and then measuring the frequency produced integrating the frequency pulse (traslating in a voltage value) and connecting to a meter with a scale in microFarad or microHenry.

Another is the same doing digital frequency measurements and with a simple algorithm, done embedded into LC meter, the value unknown is shown on a readout.

There are also LC meter that do the measure using a microcontroller but the principle is the same.

Maybe naive, but this is a very simple explanation.

Ciao!

 

[nhoj]

measuring capacitance in ads agilent

grey and heyheyhey,

tnx to your reply... i'll try doing some experiment...

your helped points will just follow after i finished working with it...

again tnx...

 

[raghuram_msc]

kelvin bridge measure capacitor

Dear Buddy,

I jsut remember having been studied these Bridges ( for measuring L,C,R):-
Wheatstone Bridge,Maxwell's Capacitance,BridgeDe Sauty's Bridge,Schering Bridge,Owen's Bridge,Anderson's Bridge,Maxwell's Inductance Bridge,Kelvin's Bridge....etc.... ( I donot remember which is for what..Sorry..!!!!)

Try running little Google on this...May be u should get help.

Sai

 

[erp]

measuring capacitance using schering bridge

well, to measure inductance :
- maxwell bridge, for (1<Q<10)
- Hay bridge, for (Q<10)

to measure Capacitance:
- Schering bridge

Sorry, i can't bring details for now,
for more information, you can also read book or article with electronics measurement and instrumentation on ac bridge section