Slab Desynn

If the voltage at the 3 tappings of the transmitter of a basic Desynn are measured as the wiper arms are rotated 360°, it will be seen that they produce a sawtooth waveform as opposed to a sinewave. 
This results in the pointer of the indicator not following the transmitter exactly.  In most instances the difference is insignificant, however their may be certain circumstances where it cannot be overlooked.

The solution is to use a modified Desynn transmitter called a 'slab Desynn'.  In a slab Desynn, the resistor is wound on a slab former and has the power supply connected to it, whilst the wiper arms now provide the output to the receiver, there being 3 wiper arms each displaced from the next by 120°.  The output from this device is a sinewave.  It can be connected to the same type of indicator and operates in the same way as the basic Desynn.