Regardless, to perform which operation you will use the diode, when it is selected be sure to include such basic parameters as the maximum allowable forward current and reverse voltage. If the value of the pulsed direct current is much higher than the average, account for it, especially if the diode is a semiconductor.
If you need to straighten the currents of significant frequencies, note also the performance of the diode. Point semiconductor diodes have less capacitance than planar, and therefore, right currents a significant frequency. But they are very thin. The same property with a much larger capacity, and have a Schottky diode.
Correctly select the physical principle of operation of the rectifier. If the diode requires a complete absence of reverse current, but the efficiency is unimportant, use of the vacuum-tube diode. He's good that starts to straighten with a small voltage value.
Coproxy rectifier also open at low voltage but very high reverse current, low power, and performance, it is relatively small. Use it to straighten small alternating voltage of low frequency prior to measurement.
A germanium diode is opened when a slightly larger voltage, but the reverse current it has less. Use it, in particular in detectors of amplitude-modulated signals.
From selenium rectifier voltage large opening and little permissible reverse voltage, therefore, for rectifying significant voltage connect them in series. Appreciable reverse current allows to exclude the equalizing resistors. These rectifiers can withstand momentary short circuit, but after a long work break down for no apparent reason. Use such devices only in instances when no other diodes to replace them is impossible.
Silicon diodes are the most common today. They almost replaced the rectifiers of other types. Among them you can choose the instrument with virtually any necessary parameters. Try to apply them in all cases when possible.
Having defined the requirements for the diode, find the suitable for all parameters of the device in the directory.