The totem pole design can be configured with cathode followers for an even lower output impedance. The main reason is the low output impedance. Now that we have identified the totem pole design as push - pull, why would you want to use it instead of the usual push pull design. This is common in switching power supplies but I have never seen it used in analog audio. It is possible to build a four phase push - pull design. If the output devices are driven by two (or more) signals of differing phase the design is push - pull. If all of the output devices (tube or transistor) are driven in phase with each other the design is single ended. There is always some confusion in unusual multiple tube designs as to whether they are single ended or push - pull designs. However it is not a single ended design, it is a push - pull design. We have shown that the totem pole design can be made from two single ended stages. Shown below is the evolution from a single ended output stage to the totem pole design.
Most of the early solid state amplifiers used this configuration, some even stacked 4 stages on top of each other in an attempt to make up for the low breakdown voltage of the early transistors. Controllers can compare each pair (“A” must be equal to inverted “/A”) to ensure that there is no error during the transmission.Īdditionally the transmission sensitivity is improved by transmitting the differential signals through a twisted pair cable.Named for the fact that single ended stages are stacked on top of each other in “totem pole” fashion. These signals are inverted “A”, “B” and “Z” signals.
Some incremental encoders also have additional differential signals, called “/A”, “/B” and “/Z”. This can be used as an accurate reference point. Once every rotation, this Z signal is rising for typically 90°, on the exact same position. By turning the encoder clockwise, the “A” pulse is rising 90° ahead of the “B” pulse, by turning the shaft counterclockwise, the “B” pulse is rising ahead of the “A” pulse.Īdditionally some incremental encoders output a “Z” signal. These 2 signals are set up with a 90° offset, which is required for the detection of the encoder’s rotation.
One sensor must be connected to one controller.Īn incremental encoder has at least 1 output signal “A” or typically 2 output signals, called “A” and “B”. Incremental rotary encoders provide a serial output signal on a single transmission line.
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