Technoroam Lasershow

Last Update: 23.11.2007

This site contains some informations related to my homebuilt lasershow. Until now I have built two simple projectors where
G120D galvos with my own amplifiers (see below) are used as scanning system. First projector uses Viasho VB-150
150mW 532nm laserhead, second one has Medialas DPGL 50 A   50mW 532nm laserhead.

As controller I'm using slightly modified ChaN's LDP2, which plays frames from standard SD Card.
LDP2 can be controlled via keyboard, RS232 (using any terminal program like HyperTerminal),
or via DMX input.

New member of my small laser family is Moncha 2.0 package by Showtacle Ltd.
Moncha 2.0 is complete solution for live performace (includes USB DAC + Windows based software ).
Without USB DAC is software working as demoversion. Check it, it's worth it :-)

1. G120D Scanner Amplifier (composed from various links from internet)

Single axis driver for G120D galvos.

Schematics: G120Amp_SCH.pdf
See also my topic on forum.

GavloAmp       PCB_top    PCB_bottom
Finished Driver                                   PCB Top                                                       PCB Bottom

Here are the test pictures (Power Supply = +/- 20VDC):

A) ILDA Test Pattern at 15Kpps @ 40° optical (+/- 20°)

15Kpps @ 40° optical            15Kpps @ 40° optical            15Kpps @ 40° optical

B) ILDA Test Pattern at 20Kpps @ 20° optical (+/- 10°)

20Kpps @ 20° optical            20Kpps @ 20° optical

C) ILDA Test Pattern at 24Kpps @ 8° optical (+/- 4°)

24Kpps @ 8° optical            24Kpps @ 8° optical

Full step response (Power Supply = +/- 20VDC):

The G120Amp is adjusted so that position detector produces Vpos = +/-5V @ +/- 20° ( = 40° optical, maximum possible scan angle of G120).
Input signal was square wave (50/50) f = 50Hz with amlitude of 10V connected to  Vin+  input ( Vin- was grounded ). G120Amp is adjusted
so this signal produces maximum possible scan angle.
Whole G120Amp was tunned so ILDA Test Pattern runs correctly at 15Kpps @ 40° optical (+/- 20°) (see test pictures section A).

Command:                                             Response:      
Vin+            Vpos

Adjustment procedures:

You can look here for some details about how to adjust (tune) the amp.

Closer look on setup where all tunings have been done:

Setup1        Setup2         Setup3         Setup4

I bought my first pair of G120D in July 2005. They worked, but their condition was not very well (torsion bar was several times replaced, bearings not I think).
I was able to get maximum 15Kpps @ 40° optical, 18Kpps @ 20° optical. When scanning angle was decreased there was no improvement in scanning speed.
Price was few hundred EUR for one pair !

In May 2007 I met one guy on eBay who was selling General Scanning galvos which looked like G120. Starting price for one piece was 35 USD,
which was unbelievable !  This guy offered 46 pieces !!! I was not 100% sure, that it is G120, beacuse General Scanning produced also custom made galvos.
Nevertheless I bought 4 pieces of galvos for 140USD. Transaction was smooth, galvos arrived without problems. One think I had to do was to replace
connectors, because my G120Amp has Sub D connector, and my new galvos had connectors which will fit to MiniSAX driver.
Then I connected new galvos to my G120Amps, carefuly tested and tunned as required. The rest you can see on test pictures. Now I think my new galvos
are G120 with thermal blanket (orange stripe on galvo). They are working perfectly. I didn't make any changes to my amps. All results were achieved
because my new galvos are in very good condition (they are "used but well cared for" as it was stated on eBay). One remark: After I won 4 pieces, these guy
still had 24 pieces available. He will be for sure re-listing them. His name is "finalphase2".

2. Laser Display Controller 2 (designed by ChaN

Schematics with my modifications: LDP2_SCH.pdf


Most important for me is added DMX input. It uses USART1. I found useful DMX routines on
Original code was written for PIC16F876 microcontroller.
I only adapted it for AVR microcontrollers.
Also symetrical (balanced) output for X & Y channels added.
Beacuse of  some hardware modifications (I/O port connections), also orginal ChaN's code needed to be changed.
It's now working perfectly :-)


Frames or animations are stored on SD Card in Chan's own file format. ILDA files can be easily
converted to this format. It supports only one color and TTL modulation.

3. Projector 1

This was my first attempt to built laser projector. In the beginning it was equipped with G124 open loop galvos manufactured
by General Scanning . Lot of pictures of the first version are available here . Based on the information at ,
using amps called Accelerator124, these open loop galvos can reach 12Kpps.
As it was stated above, I was able to get true closed loop galvos called G120D. G120D was industry standard many years ago.
But today still fast enough for me :-)

So one pair of G124 including amps is now ready for shipment if somebody is interested. It could be a decent start for
any beginner in this area. Contact me if you would like to have them. Closer look on what you can get is here .

Some photos after improvements:

Scanner 1        Scanner 2         Scanner 3

Front 1        Rear 1            Rear Inside 1

Inside Front 1        PS 1            Scanner 4

Temperature Sensor 1        Temperature Sensor 2            PS 2

PS Heatsink 1        Connectors 1

Comments will come soon.

Schematics:  Scanner Amplifier ,  Power Supply ,  Power Entry Module ,  Control Board ,  Projector 1 Wiring .

4. Projector 2

Preliminary version:


More photos of finished projector2 and some comments will come soon.

Schematics: Scanner Amplifier , Power Supply , Control Board , Projector 2 Wiring .

5. Links

6. Disclaimer

Any information provided on this site is not guaranteed in any way. All informations here are provided
for educational purposes only,
USE THEM AT YOUR OWN RISK ! If you blow up your galvos, home,
computer, or anything else -- it's not my fault,
use good judgement and play nice.

7. Contact

Questions ?  Just send me an e-mail.

laserfreak at technoroam dot sk

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