The simplest case occurs if the body diode has the symbol. It consists of an equilateral triangle and cut a straight line, in which the triangle rests on one of its corners. On diode's, marked by a new standard, this designation would further like crossed - the essence remains the same. Let's see how precisely focused the designation on the findings of the diode: the one that is closest to the triangle, corresponds to the anode, and the one that is closest to a line segment - the cathode.
If you know exactly what type of diodeand there is a guide or Datasheet to determine the polarity. View, about which conclusions should be the point (or several points) or a circle. Sometimes by number or color dots, you can optionally specify the prefix of the diode within a series, and it in turn is the maximum reverse voltage.
If the diode has no signs and all you know about him is the forward current and reverse voltage, determine the polarity in the following way. Take an ohmmeter (or multi-function apparatus, which has such a function). Determine the polarity of the voltage on its probes in the measurement mode of resistance, using as a model the other diode, the Pinout is known. Then, connecting the test probes to the diode of the subject in different ways, determine the location of its electrodes at the analogy.
Very useful for determining the Pinout of the diodes use a special probe. Take two penlight batteries, a led, a resistor of 1 kilo Ohm and two testers. All the parts connect in series, and the polarity of the inclusion of the diode determine experimentally that with the closure of the probes it was glowing. The test diode, connect the probes, first in one polarity, then in another. When the led glows, the output of the diode isfacing the negative pole of the power source is the cathodemodulation.
Advice 2: How to determine the polarity of the diode
Any diode changes its conductivity depending on the polarity of the applied voltage. The location of the electrodes on his body indicated not always. If labelling is missing, to determine which electrode is connected to what pin, you can own.
First, determine the polarity of the voltage on the probes that the measuring device you use. If he is rich, put it in the mode of the ohmmeter. Take any diode on the body which indicated the location of the electrodes. This designation of "triangle" corresponds to the anode, and "strip" the cathode. Try to connect the probes to the diode in different polarities. If it conducts current, then the probe to the positive potential connected to the anode and negative to cathode. Remember that the polarity in the mode of measurement of resistance to pointer instruments may differ from that which is provided for measuring voltage and current. But on the digital devices it is usually the same in all modes, but to check still won't hurt.
If checked the vacuum diode with direct heat, first locate it a combination of pins, between which the current flows regardless of the polarity of connection of the measuring device. This - the filament is the cathode. Through the directory, find the rated filament voltage of the diode. Served on the filament DC voltage corresponding value. The probe of the device, which is a negative potential, connect to one of the pins of the filament, and the positive probe touching turns to the rest of the insights of the lamp. Upon discovering the pin, when you touch the probe to which displayed resistance, lesser infinity, conclude that it is the anode. Powerful vacuum diodes with direct heat (rectifier tubes) can have two anode.
Vacuum diode with indirect heat heater insulated from the cathode. Finding him, sue him alternating voltage, the effective value of which is equal to the specified reference. Then among the other insights find the two between which at a certain polarity passes current. The one that is connected to the test lead with the positive potential, the anode is opposite the cathode. Remember that a vacuum diode with indirect heat have two of the anode, and some two cathodes.
A semiconductor diode has only two pins. Accordingly, the device to be connected to only one of two ways. Find a element position at which the current is passed through it. Test lead with the positive potential will be connected to the anode and negative to cathode.
Do not connect measuring instruments to the circuits under voltage.