How to measure pulsed current on electrical circuit??

In some cases, pulsed current generator is needed, such as of LED performance test. In that case, LED need to be injected by pulsed current. Actually, there are some company that produce and sell pulse current generator but it is usually very expensive. To solve this problem we can use pulsed voltage generator instead of it which are cheaper than pulsed current generator.

By using pulsed voltage generator, we may be confused how to measure the current. Pulse current is difficult to measure because of two reasons. First, it is pulsed, so we cannot measure the current by ampere meter or clamp ampere since those are for constant current. Second, it is current which cannot be measured by oscilloscope. So, how to measure it??

To measure pulsed current on electrical circuit, we need a known resistant (such as resistor) to be attached serial on the circuit. Then, activate the circuit and measure voltage at the resistor by oscilloscope. By this method, voltage can be measured and resistance is already known. As known that currents at serial connection have same value, Then by simple equation that current value equals voltage divided by resistance (I=V/R)current can be calculated easily.

Also we can control the current by controlling voltage of pulse generator. If we can’t control the voltage we may use potentiometer. These have the same principle, (I=V/R). When we control voltage of pulse generator it means we change V. And the other hand if we use potentiometer, it means we change the resistance(R).

In using pulsed generator, be careful to set the current (it means set up voltage and selection of the resistor). If current exceed generator limit (see the specification of generator), it may cause damage to it. If it happens, fuse inside generator will be cut. But if fuse is already broken, damage may occur in generator component.