AC ammeter

AC ammeterSometimes we really need to measure AC current. What do we do if there is no appropriate meter at hand?Analogue probes are mostly for DC current. Same with multimeters. Only the most expensive models can measure AC. What can we do in this case?The solution is simple. You need to add a diode bridge to your measuring instrument. However, it must not be used to rectify current. The current using equipment needs AC, so if you try to feed it with DC, it may be irreversibly damaged.In order to get an AC ammeter you need to connect your ammeter according to the following schematic. Indeed, if the half cycle is positive, the current will pass through D1 diode, then through D2, and finally get to the load. If the half cycle is negative, the current will run through D1. The diode will be blocked. The current will run through diodes D3 and D4 instead. Again positive voltage will be applied to the positive pole of the ammeter.Let's assemble this ammeter and try to measure something. We will need a probe and a diode bridge suitable for the maximum current we are going to measure.It is better to use an analogue probe. This will ensure that the readings are correct. As you know, a digital multimeter may inflate values.We form the diode bridge and mount it onto the inspection probe. Make sure the plus output corresponds with the plus of the diode bridge. Now let's apply some load. As we can see, the ammeter is connected to the break in the circuit.Now if you ever need to measure AC, you can always quickly make a meter of a diode bridge plus any DC measuring device. What is more important, you don't have to disconnect the bridge in order to measure DC again (but only if you can neglect the diode's resistance). Additionally we created polarity reversal protection. Now every time you apply DC to the circuit, the needle will be deflected correctly.