galvo position sensor??

[WonHungLow]

im building my own galvo's for a scanner(based on Chan's design)
the build is going smooth so far.
the question i have is... what is he using for position detection of the galvo.
i see no IR detector/emitter or optical encoder.

what would be a fairly simple position detection that i could integrate into the build.

this is his site
ELM - Home Built Laser Projector

i have found another build that uses the IR emitter and detector. is this precise enough for vector based graphics.

 

[Cyparagon]

Did you actually read the article? It describes the position detector in several different places. It's not IR, it's capacitive.

 

[Bionic-Badger]

This qualifies as a stupid question because it's obvious that you didn't do any reading on the site at all. Go to the page, hit Ctrl-F and search for "position".

On another note, while ELM's capacitive detection method does work, it increases the mass of the system which can reduce scan speed. Most galvos instead rely on a "paddle" that affects the amount of light sensed by two photodiode/LED pairs to detect position. Open up a cheap galvo and you'll see how it works.

 

[WonHungLow]

sure is good to know that smart asses are still around on the internet. (badger)
i figured it out after i made the post.
it just didnt click with me how a rotating plate pressed against another was capacative.
makes a little more sense now. i just dont imagine it to be precise.
i just didnt run back to the forum wasting anyones time to say "neverming i got it" to get my post count up..
u have a habit of being a troll. if someone has already answered a question that was "stupid" then what makes you even reply.
just to get your useless comments in.

badger here you go...


have a nice day :thanks:

 

[Cyparagon]

 

[Bionic-Badger]

Your LMFG link in the context of this topic is pretty ironic.

 

[LSRFAQ]

Last time I checked, and I've been doing this for 25 years, capacitive was pretty darn accurate. especially the way Chan did it. Its still used on industrial positioning systems for ultra precise marking. It takes a two led, four detector system to beat capacitive on over all accuracy.

Steve