Is it possible to see current signal on oscilloscope. Since we can only see voltage signals directly on the oscilloscope. One way can be, to use a shunt resistor and look at the voltage signal across it ( I=V for 1ohm resistor) but with that method I couldn't realize the signal I was expecting. Any other way ?
Thanks
One can use a resistance to convert the current into voltage according to the simple relation V=IR. But there are some preconditions not to disturb the circuit by adding R. This requires that the voltage drop on the R must be negligibly small compared to the voltages on the series components. The other condition that it must be pure ohmic not to distort the currentwaveform.
It is will known as the resistance becomes smaller it shows ohmic behavior up to very high frequency. The problem may be then that the voltage across the small current measuring resistance will be so small that can not be resolved by the oscilloscope. Then one has to amplify this voltage to the level that can be displayed by the oscilloscope. Again the amplifier must not cause any remarkable signal distortion.
The current sensing resistance is a widely used technique in the measurements.
Best wishes
It very much depends on what range of current to be measured. Once you know the range of current, you need to make a circuit involving known resistor. I would suggest if you could ask someone who work in the electronics workshop to make a circuit. This can definitely be done to indirectly measure the current on an oscilloscope.
There are special 'current probes' for oscilloscopes, however they are rather expensive :
https://www.keysight.com/en/pc-1659326/oscilloscope-current-probes?cc=IE&lc=eng
Common problems observing current with oscilloscope is that parasitic inductance of the resistor may dominate. One should use low inductance resistors of adequate value.
Also, what can be used sometimes are current transformers and Hall sensors (available as electronic components). That is what the 'oscilloscope current probes' are made of. The Hall sensor allows you to observe DC signal while current transformer not.
Dear Abbas,
the idea, to convert a current into a voltage by using an Ohmic resistor is OK. But your proposal - using a shunt - is not a good idea, if I understood you right. Here, you only reduce the input resistance and probably your voltage drops down.
You must open the electrical line and introduce a serial Ohmic resistance RS, may be 1 Ohm. It is important that the serial resistance is smaller than the resistance of your voltage source. You must conserve the electrical parameter. Lets say the parameter must change not more than 1%. The ohmic condition is necessary to prevent an additional phase shift of your signal.
If you hold all conditions
- serial resistance
- Ohmic resistance
- RS
Voltage & resistance ( non-active) can be measured open circuit or parrallel stage of part of any closed circuit carrying current. Current can be monitored by clip on loop with ratio presentation. Anyway for monitor current sensor parrallel to circuit will be needed even counting electron flow in circuit. To see inside closed, parallel action will required in any ratio for calibration. Current probe also take small ratio of current and sensing voltage across standard register to show on oscilloscope ( it will include active restance and variable voltage). Caliberation of ratio will make display on oscilloscope.
Definitely use current probe. Also with some kind of current probe, you can measure also a DC current. Using a probe it is more comfortable to made a measurement work.
Either use current prob or convert it in corresponding voltage format by using a resistor.
you can not see a current signal in oscilloscope but you can see the image of the current using a resistor in //
the real value of the current is I = U / R
One can use a resistance to convert the current into voltage according to the simple relation V=IR. But there are some preconditions not to disturb the circuit by adding R. This requires that the voltage drop on the R must be negligibly small compared to the voltages on the series components. The other condition that it must be pure ohmic not to distort the currentwaveform.
It is will known as the resistance becomes smaller it shows ohmic behavior up to very high frequency. The problem may be then that the voltage across the small current measuring resistance will be so small that can not be resolved by the oscilloscope. Then one has to amplify this voltage to the level that can be displayed by the oscilloscope. Again the amplifier must not cause any remarkable signal distortion.
The current sensing resistance is a widely used technique in the measurements.
Best wishes
Better to use current probe for current reading in oscilloscope. Otherwise use a very small pure reistor to conert the current signal into a voltage signal. But there is chance of distortion of the signal.
Dear Abbas N.
In the following link you can see three ways to measure current by oscilloscope:
https://circuitdigest.com/electronic-circuits/how-to-measure-current-with-an-oscilloscope
you can use a resistANCE AND CONVERT current to a voltage and then use the oscilloscope
Are you looking for a mostly DC measurement, or are you looking for an AC measurement? Can you share the expected magnitude (maximum and minimum) of the current you are trying to measure? Also, what is the expected frequency range? If your application is a very low current, you may need some form of amplification to obtain your desired results.
Thanks,
Carl
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