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Vacuum tubes, metal oxide rectifier stacks and semiconductor diodes are useful in the range of milliamperes to several thousand amperes of current in a single device.

Some interesting electromechanical solutions have been devised and were used before the advent of electron devices. For example, to convert AC current into DC current in electric locomotives a synchronous rectifier may be used. It consists of a synchronous motor driving a set of heavy-duty electrical contacts. The motor spins in time with the AC frequency and periodically reverses the connections to the load just when the sinusoidal current goes through a zero-crossing. The contacts do not have to switch a large current, but they need to be able to carry a large current to supply the locomotive's DC traction motors. In the past, the vibrators used in battery-to-high-voltage-DC power supplies often contained a second set of contacts that performed synchronous mechanical rectification of the stepped-up voltage.

In recent years semiconductor synchronous rectifiers have been designed; using MOSFET transistors, they can also rectify with a very low forward voltage drop and have the additional advantage of being able to switch at extremely high speeds. Semiconductor synchronous rectifiers are now widely used in those electronic power supply units designed for very low output voltages (where the voltage drop in an ordinary rectifier would represent an unacceptable fraction of the total output voltage).

Another type of rectifier used in high-voltage direct current power transmission systems and industrial processing between about 1909 to 1975 is a mercury arc rectifier or mercury arc valve. The device is enclosed in a bulbous glass vessel or large metal tub. One electrode, the cathode, is submerged in a pool of liquid mercury at the bottom of the vessel and one or more high purity graphite electrodes, called anodes, are suspended above the pool. There may be several auxiliary electrodes to aid in starting and maintaining the arc. When an electric arc is established between the cathode pool and suspended anodes, a stream of electrons flows from the cathode to the anodes through the ionized mercury, but not the other way. These devices can be used at power levels of hundreds of kilowatts, and may be built to handle one to six phases of AC current. Mercury arc rectifiers have largely been replaced by silicon semiconductor rectifiers from the mid 1970s onward. The most powerful mercury arc rectifiers ever built were installed in the Manitoba Hydro Nelson River Bipole HVDC project, with a combined rating of more than one million kilowatts and 450,000 volts.

The General Electric Tungar rectifier was an argon gas-filled electron tube device with a tungsten filament cathode and a carbon button anode. It was useful for battery chargers and similar applications from the 1920's until low-cost solid state rectifers supplanted it. These were made up to a few hundred volts and a few amperes rating, and in some sizes strongly resembled an incandescent lamp with an additional electrode.

Another type of rectifier, a motor-generator set or the similar rotary converter, is not a rectifier in the strict sense. Here, an AC motor is mechanically coupled to a DC generator. The DC generator produces a multiphase alternating current in its windings, but a commutator is used to convert the alternating currents into a direct current output; or a homopolar generator directly produces direct current without need for a commutator. Such devices are useful for producing thousands of amperes of direct current at tens to hundreds of volts.