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Topic: Position sensing detectors (Read 910 times) previous topic - next topic

Gizmo

Hey guys,

I'm trying to interface with a few Position sensing detectors (PSD) from Thorlabs:

http://www.thorlabs.com/NewGroupPage9.cfm?ObjectGroup_ID=4400&pn=PDP90A

sensors are Vcc +-5V +-5%  9x9mm
Output is 3 DC signals per unit at about 12 bits precision with max output of +-4V.
Max output power is based on laser power so it is variable.

Obviously, we are talking about lab quality equipement so precision is outmost priority.
I was planning on averaging measurement every few cycles to reduce noise and maybe even input on multiple pins.

Output is simply showing data on a 4x20 LCD screen

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First, you have to understand that this stuff is new to me. I probably spent 100 hours on that since the last 2 weeks. I'm a mech eng so I'm sort of venturing to the dark side here...
Anyway... I was trying to few an alternative to thousand $$ cards when I found out about the arduino. It kind of seemed to good to be true at first.
Then I realized that the ATMega 8 bit is only using a 10bit A/D wich lets face it looks like a dealbreaker. I found out that it is possible to bolt an outside 12+bit A/D.
After, I found out about the Leaflabs Maple with its 32bit (no need) ARM processors and 12bit A/D. I then realized that this bitch is running 3.3V


Questions:

1. Noise level: Usually, is it beter have sensor running at high or low voltage (3.3 or 5V)?
2. Noise level: 12 vs 72MHz MPU , is it going to matter?
3. I/O: Lets say my max output voltage is about 4V, should I use that as my reference voltage for more precision?
4. Any Sheild with a 12+ A/D
5. On a general basis, is it better to supply voltage to sensors from the board or outside powersupply?
6. In my case, ATMega (arduino) or ARM (Maple)?
7. Any tip on a general, professional looking electric connector to join the LCD and Arduino? (Hirose?)

Thanks a lot!

Gizmo

Forgot question #8...

8. Lets say my sensor output was to go above 5V (or 3.3 for the Maple), would that fry the pin/controller or is there some kind of over voltage protection?
9. Is there some kind of easy over voltage circuitery available?

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