Not my Auction, But....

[mixedgas]

Not my auction but...

These are flexure based galvos. They have built in return springs.
If you do NOT drive them into the stops they make OK actuators or remote scanners.
You'll need a controlled current or voltage to drive them, as just putting 12V across them in the classic actuator manor hurts them.

If you drive them into the stops, it breaks the postion sensor butterfly which is ceramic.This jams the rotor, and removing it is possible, but not for the mechanically timid. Nor are there really stops, so just DONT overdrive them.

They even have rails for mounting bolts.

50$ a pair is decent. They move HUGE mirrors.

I have one working one, and one I cut open for RE. this guy beat me to them at my source. I've reverse engineered the position sensor if you want to go closed loop.

If you buy a pair, I'll PM you a open loop driver schematic off list.

They might work well with Dave's little open loop driver, but this is untested.

http://www.ebay.com/itm/PAIR-GSI-LUM...item2a19092b38

These are the last Galvo GSI/LUMONICs/Cambridge makes with a torsion return system, so unlike Chivos, they can run open loop. FM3 or similar part number.

KPPS is not applicable here. These are slow, but useful. They also have near ZERO cross axis motion with a big mirror, which is why they are in platemakers. With a .250" shaft diameter and a bolt on mirror mount (easily reused with smaller mirror or a arm) PPS is not really applicable.

Heed my warning, drive with a constant current source or a small open loop amplifier with a input gain potentiometer. Since its Flexure, there are no bearings to wear out.

Or just drive them with a carefully chosen filiment transformer for a 50-60 Hz remote scanner.

I will train the source to route them to me, I'll sell them on PL, and keep the cost down. I've been dealing with them for years, and have a "relationship" with them. I doubt I'll have to pay more then 10$ each for them.

Steve

[Stoney3K]

What's the impedance on the coils on these? Is it anywhere near the range you can drive with a standard old-school audio amp?

[mixedgas]

Yes, I just tried it with my stereo. Works well.

Ohm meter says 33 ohms, for this one here, so a good 16$ PC speaker amp with capacitive coupling will drive them at small angle.

Worse case, get a 8 ohm to 70 Volt** Line Audio transformer for 6$ on Ebay
Most older galvos are close to 7.5 ohms, newer ones are closer to 4 ohms or less, so very compatable with audio amps.

If I have time in the morning I will measure volts per degree at DC. Judging from the considerable number of turns on the coil, I imagine the number is very favorable compared to most galvos.

The RF based feedback sensor runs on 12 volts and outputs differential currents. I use two simple, 3 component, LC lowpass filters to get rid of the residual RF on each output. The signal is then run into a quad opamp chip for processing and summed. This is the classic way before galvos went to optical feedback.


** Doesnt Europe use 32 Volt Line ? for Public Address /Tannoy systems ?



Steve

[dnar]

Europe use mostly 100V line constant voltage, while the US mostly use 70V. All our CV products provide both, as we well in to 75 countries.

[mixedgas]

Also, adding variable damping to a simple open loop amp, is trivial and consists of 5 passive parts.

Steve

[planters]

Steve,
I have been struggling with the galvo problem for some time; small and fast vs. big and slow. Big and slow being the 10 mm EMS 4000. Small and fast waiting for the EMS 7000/Cambridge face off. Without drifting too far off topic these scanners your describing might solve a related problem. Running with Beyond I thought about a second projector, but P. wants $1,400 (essentially a second complete package) in order to provide a second FB3 and so what about a satellite driven by audio input from the selected music producing geometric patterns?
How big are the mirrors?
Coating?
Could they handle a high power 532?
How difficult would a closed loop driver be to source?
I don't have any illusions that these are going to be fast,big and cheep, but they might be an alternative. Yes?

[uamdme2]

Steve,

I bought a pair of the GSI Lumonics galvos, if you would PM me the open loop driver schematic off list that would be a big help.

Thanks
Gary