[TowerTalk] synchro to RS232

[Martin Sole]

Hi Grant, that was me, and I think Jim Lux. Many thanks for the link.

Martin, HS0ZED


On 07/12/2018 05:05, Grant Saviers wrote:
> Not sure who was looking for the voltage/current equations for 
> synchros but some data is in MIT Rad Lab Vol 25 Chapter 3.  Found by 
> accident.
> https://www.jlab.org/ir/MITSeries/V25.PDF
>
> Grant KZ1W
>
> On 11/19/2018 15:28 PM, jimlux wrote:
>> On 11/19/18 1:41 PM, Al Kozakiewicz wrote:
>>> The defeat of the Nazi's assisted by this analog technology has 
>>> almost passed completely from living memory.  Rotary encoders are a 
>>> fraction of the price and already signal compatible with digital 
>>> systems.
>>>
>>> Or maybe I am missing something?
>>>
>>> Al
>>
>>
>> Synchros (and these days, resolvers) are still widely used as sensors 
>> - they're really rugged, inherently a balanced ratiometric device, so 
>> wire length isn't a big deal, and its all twisted pairs (or triples) 
>> so noise pickup is less of an issue. They laugh at ESD or transients 
>> - it's a transformer - unless the discharge is big enough to destroy 
>> the winding, it still works - you can punch holes in the insulation 
>> with HV transients all day.  They are also inherently 
>> dust/moisture/liquid insensitive - the accuracy is more about the 
>> quality of the shaft bearings and how precisely they can locate the 
>> rotor within the stator windings.
>>
>> You can easily transformer isolate them for galvanic isolation (a 
>> real issue with long sensor wire runs - galvanic isolation is good)
>>
>> Unlike a quadrature encoder, they're an absolute position sensor - no 
>> need to "find home" and count pulses.   Yes, there are absolute 
>> rotary encoders, but they don't have 16 bit accuracy, without a 
>> geared scheme and two encoders.   16bit accuracy is achievable off 
>> the shelf with a resolver at moderate cost (a few kilobucks, brand 
>> new, for resolver+chip to turn it into a digital number).
>>
>> You'll also see the linear equivalent called a LVDT (Linear Variable 
>> Differential Transformer)- same basic idea, a transformer made with a 
>> stator with multiple windings, and  a slider that has an excitation 
>> winding.  Used in the same sort of hostile industrial environments.  
>> You don't need three phases (or quadrature) for an LVDT, because the 
>> motion is constrained - no need for "unwrapping"
>>
>>
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