![synchro resolver waveform synchro resolver waveform](https://www.proway.de/wp-content/uploads/2021/06/Industrie-Messtechnik.jpg)
![synchro resolver waveform synchro resolver waveform](https://forum.dronebotworkshop.com/wp-content/uploads/wpforo/attachments/3838/2778-SynchroH-Bridges-60-180-300.jpg)
You will see that the 26V signal at 60deg angle in the diagram above is the same as the 26V signal at 300deg. This is all well and good, we have a voltage that changes with angle and there is no touching between the two parts, but it’s not possible to work out the angle of the coils as the same voltage can be generated at two different angles. Ignore the voltages, but see how the induced AC voltage changes with the angle between the two coils. Here is the best drawing of the induced voltage of this type of coupling that I could find on the Internet. Then, for any angles in between the voltage will be in proportion to the angle in fact it will change according to a cosine rule. But if you turn the secondary coil upside down, the voltage will also be upside down – we call this “out of phase”. If the two coils are both pointing in the same direction, the voltage in the second coil will go up and down with the voltage in the first coil – the two will be “in phase” with each other. In this case the coupling depends upon the distance of the air gap and the angles between the two coils. The coupling from one coil to the next is important if we want to transfer power from coil to the next, but if we are not worried about losing some power we can allow the magnetic field to pass through the air. Here is a big transformer, just to underline that it’s the same principles in use inside our synchros. The field generated by the first coil and the voltage generated by the second coil depend upon the number of windings, and this is how we can convey power from powerstations at high voltage then reduce it to a lower voltage for domestic use. The degree of “coupling” between the two coils is usually enhanced by having an iron core which guides the magnetic field from one coil to the next. A second coil with the same alternating magnetic field passing through it will have a voltage induced in the wires, so we effectively pass alternating current from one coil to the next. TransformersĪ transformer uses alternating current passing through a coil to induce an alternating magnetic field. A synchro transducer is a form of transformer, so let’s have a quick reminder of the key things about a transformer. It may not actually stop working, but it may well lose accuracy.Ī better solution would be to measure the angle without any contact between the rotating and stationary parts and this is what a synchro transducer achieves. For example, if we measured roll attitude this way, the “wings level” setting at 0 degrees roll would be in use most of the time, and with a little aircraft vibration to help the wear process along I am sure you can see how the potentiometer could get damaged. This is really simple and cheap to manufacture (I am sure potentiometer manufacturers would disagree) but potentiometers have a fundamental weakness because the wiper rubs on the resistive strip and it is common for normal operation to be over a small angular range. A wiper is attached to the rotating shaft and this picks up the voltage according to the angle of the shaft. All of these are either angles to start with, or can be expressed in terms of the angle of rotation of some part of the control mechanism.Ī simple way to record these angles is to use a potentiometer which has an arc of resistive material with a small current flowing through it, which results in a continuous drop in voltage. Similarly we need to measure the position of components such as the flaps, or the ailerons. For example the pitch, roll or heading angles. We often need to instrument the movement of an aircraft. So here we go for a dive into synchroland. One of my colleagues recently asked if I could explain to him how a synchro works, and I thought that rather than just telling him once, I would thrash out a quick blog on the topic for posterity.