Resolvers.. Still a viable with current technology..

[skunkworks]

Working on getting a 70's vintage nc lathe running I have also been playing with resolvers. Granted there are comercial solutions that work better (pico and mesa)

[skunkworks]

part 2

[RB211]

Resolvers I have are from aviation and designed for 400hz AC.

[skunkworks]

These are rated at 400hz also. They seem to work good at 2khz.

Resolvers I have are from aviation and designed for 400hz AC.

[RB211]

But you must feed them that signal. There exists resolver motors and others. So apparently you can drive something 1:1 electrically.

[macona]

Analog Devices makes resolver to digital ICs. Not too expensive and handles excitation and A to D. They even have simulated quadrature encoder outputs: https://www.analog.com/en/products/ad2s1210.html

[MaxHeadRoom]

Resolvers were used in early CNC M/C's but as mentioned they have inertia and also require excitation etc.
The modern replacement is the quadrature encoder used with the direct photo-LED sine wave output before it is squared up as in the typical quadrature versions.
The co-tangent calculation is the same result as the resolvers were.
.I recall the first optical quadrature encoders/scales that had an incandescent lamp for use in the read head, every time you replaced the bulb, the resulting sine wave phasing had to be done with a scope using a Lissajous figure to set the 90deg offset. !!