This is a optical position sensor with an array of photodiodes and a source LED.
You understand that in a proper Galvo amp, Sensor linearity is corrected by adding position feedback signals to the LED current in a controlled manner, yes?
Ia and Ib are the photocurrents from the position detector photodiodes. Note the need for 1% resistors in most parts of the detector circuits.
The first drawing is the position demodulator difference amp. The second drawing is the Position Detector LED supply with Automatic Gain Control for the Linearity Correction.
Note that Va and Vb from the demodulator are tied to the Va and Vb inputs on the AGC schematic.
R13, Position Linearity sets the current in the position detector LED.
The third drawing shows the LED and Photodiodes in the galvo.
The schematics shown are from a generic galvo amp.
As far as I know there is no such thing as a DT40 Data Sheet beyond what is on the DT web site.
Amplifiers are very inexpensive. Why you would want to build them, I cannot understand.
Steve
Last edited by mixedgas; 02-25-2015 at 13:02.
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