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measure current by Scope

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dr.power

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Hi guys,

Can I measure the amplitude of AC current passing through a component like a speaker DIRECTLY by a scope at an specific frequency? Or just am able to measure the voltage across it?

Thanks
 
Thanks but I am indubt if I put the scope probe in series by the measured load? Can you say me what parameter it measure and what is p-p waveform I see in this situation?

Thanks
 
If you put the scope in series with the load, then you will just measure the open circuit voltage of the amp. The high impedance of the scope prevents any significant load current from going through the speaker.

As Nigel said, you have to put a small resistor in series with the load and measure the voltage across that to get the current.

It would help if you did some study on series and parallel circuits.
 
If you put the scope in series with the load, then you will just measure the open circuit voltage of the amp. The high impedance of the scope prevents any significant load current from going through the speaker.

As Nigel said, you have to put a small resistor in series with the load and measure the voltage across that to get the current.

It would help if you did some study on series and parallel circuits.

lol, Ok thanks, I got what was my fault! I just did not take this fact into account that the scope is high impedance so that could measure voltages without affecting them.
Is it matter which voltage (P-P or RMS) I measure so that I calculte current by OHMS law? I think using P-P yields to P-P current, and using RMS voltage yields RMS current, Right?

Thanks for everything
 
Yes, P-P voltage measurement would yield P-P current and RMS voltage measurement would yield RMS current. Either method obeys Ohm's law.
 
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