15kpps Laser X-Y Galvanometer and control board - Page 1
Forum section: electronics / projects

author: GreyArea
author_rank: Contributor
timestamp: March 12, 2020, 02:01:51 pm
content: I've acquired this Galvanometer X Y laser mirror and controller board as a Shenzen special and I'm interested in getting it working. Unsurprisingly it didn't exactly come with a manual or datasheet but there were some specs listed.* Analog signal input impedance: 100K ± 1% Ω (single-ended input)* Analog position input range: ±10 V* Working temperature: 0~50°C* Power requirements: AC 85-285V 50-60Hz output ±15V 0.5A (DC 12V is optioanl )I'm looking for a best-guess opinion on the input supply voltage(s) and likely control voltages before I risk hooking a power supply up to it. To summarise my musings below, the questions I have right off are:* What is the likely required voltage to be applied at the V+ & V- pins?* What is the likely voltage range at the X-Y pins?* What type of connector is the center X-Y?* What type of connector is the top & bottom (X-Y & V+ V-)The specs listed seemed to be of the mirror galvanometer, noteworthy ones are as follows:* Power requirements: AC 85-285V 50-60Hz output ±15V 0.5A (DC 12V is optioanl )* Analog position input range: ±10 VThe top side of the controller board [controller_board_top.jpg] does have V+, G & V- labels on the silkscreen so I'm guessing that this spec is probably right for the controller too, and that I need to provide +15v and -15v here, I suppose a couple of off-the-shelf (or rather, off of ebay) 15v supplies could get me this, would a wiring such as  work?. I've never really dealt with split rail circuits and I haven't found one yet that could deliver >500mA.As far as the connectors go, the larger ones (strangely shared between X,Y,V+ & V-) look a little like Molex KK connectors but I have some of those and they don't fit (mine are too big), the smaller one I've no idea.For the X-Y signalling, the motor spec gives +-10V, perhaps the controller board is just the same also. The larger chips look like LM324's which, from the datasheet I found could have an max input of up to 32V, so yeah, maybe.Anyway as you can probably guess I'm groping around in the dark but hopefully I'm not too far off, what do you think?

author: chris_leyson
author_rank: Super Contributor
timestamp: March 12, 2020, 02:59:46 pm
content: Looks like a clone of a Cambridge Technology (GSI) galvanometer driver. ±15 V should be OK for the op-amp and driver supplies. Will post a schematic for a Phoenix PT40 driver when I get home.

author: chris_leyson
author_rank: Super Contributor
timestamp: March 12, 2020, 08:59:26 pm
content: Schematics for Phoenix PT40 and Cambridge 678XX galvo drivers attached, single channel only. 15V linear regulators are missing off the PT40 schematic as well as some component references. I wanted to reverse engineer the PT40 driver before I hooked it up to some Cambridge 6200H scanners just in case. Schematics also show optional notch filters. When tuning up galvos always start with minimum gain setting, there are plenty of guides on line.

author: GreyArea
author_rank: Contributor
timestamp: August 25, 2020, 01:58:44 pm
content: It's been a little while and my interest has been piqued again with this project.With the kind help of people on this forum I've managed to power the thing up with a +/-15v split rail supply and get talking to it.I managed to hook up a +/-5v AC sine wave input at 1Hz and could see the mirrors dutifully moving around. One thing I found really odd though is that the motion was extremently juddery until I also attached the 'negative' of the function generator into the center pin (ground) of one of the inputs.This leads to a bit of confusion for me, I can't really figure out why there is 3 inputs per axis. Each axis is a 3pin input labelled [X-nothing-Y]. I could understand it more easily if there was a single 3 pin input for both axes with X going negative and positive relative to ground and Y doing the same. But there are two inputs of 3 pins each.Anyone have any ideas? I had planned to use an Op-amp with a gain of 2 and my +/-5v input to provide the required +/-10v signal input but I'm not sure now.I'm waiting on the proper cables to arrive which will make things easier, so perhaps will gain some more insight then.

author: LaserSteve
author_rank: Super Contributor
timestamp: August 25, 2020, 03:00:25 pm
content: The ILDA standard uses a differential input to cancel out induced noise on long cables. To drive them single ended, drive the positive input, and ground the ground and negative input for each axis. You have a small angle bandwidth of DC to 2400 Hz or so. The bandwidth goes down as the scan angle goes up. For the other common beginner question, yes they are noisy and clack on large jumps.PLEASE see attached for the analog line driver and line receiver specs and recommended circuits. Your scanner amp has the line receiver circuit on its front end.Your "Shenzen Special" is a cut down clone version of a Cambridge 6850 amp. From visual inspection of your picture, Its missing the beefy LM3886 output stage, the scanner linearization circuits, the scanner protect circuits, the precision voltage reference, and the +/- 15 volt regulators. Thus it should run well enough on +/- 12 or +/- 15 volt supplies. Much more then that may be too hot.If you had the real true 30K Cambridge amp, it would be as in the schematic attached.. Yours is a very much cut down version of the 6850 with God only knows what else is missing from the design.My best guess is that was made by "Canton Laser Photo" or is a copy of a CLP design.Steve

author: skeeter
author_rank: Newbie
timestamp: January 28, 2023, 02:37:14 pm
content: have you made any progress using this board ?I have the same board and am trying to figure out the pins, specifically the 7 pin motor connectors