Reading strange quadrature encoder signals

fma38

Hello,

I have an motorized astronomic head mount with encoders outputing strange quadrature signals: they are sinusoid, with a low level at 60mV, and a high level at 500mV.

How can I turn these sinusoid signals to TTL, to be read by a Stamp, or a quadrature encoder counter?

Thanks,

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Phil Pilgrim (PhiPi)

Fr

fma38

You are right: I checked the original circuit: there is a LM324 to do what you explained.

Thanks,

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stamptrol

These sound like resolvers which are great for working to (theoretically) infinite resolution. Typically, the amplifier gives you large enough voltage to feed into a many-bit a/d which gives you a number proportional to angular position.

Are used to provide a signal similar to a pot, but with no sliding surfaces, no bump at the start/finish position, and continuous rotation.

Cheers,

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Tom Sisk

http://www.siskconsult.com
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fma38

Yes, I know resolvers (we use some at work). But it is much more complicated; they need sinusoid input supply. And the sinusoid is on one turn. Here, I get a sinunoid at each transition dark/light, instead of a nice square.

I don't understand how I can obtain these sinusoid here, as there is only a 5V DC supply entering in the photo-transistor...

Anyway, there is a LM324 (in non-inverter mode), followed by a 74HC14 (schmitt trigger) to make a beautifull square!

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fma38

I was wondering if the solution is not to change the phototransistor... The one used has 3 pins; the middle one is connected to +5V, and side ones are output (sinus). Do you know a product I can use instead?

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