View Full Version : What does this mean???

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07-14-2010, 06:03
Hi there,

I bought a home made laserprojector with the following specs (short)

DT40 Pro scanners
1 watt Viasho VA-II-N-532, 532nm laser (output 1,6 watt)

On the back of the laserprojector are 2 switches.

can someone please tell me exactly what they mean?


I know what TTL and Analog means, but Why the + and - ?
The OX+ and OX- doesn't ring a bell to me.

Please help me out

07-14-2010, 06:51
It most likely inverts the X galvo channel signal to mirror the image. Good if you are doing scrim versus wall projection.

07-14-2010, 06:51
im not 100%-

but my guess would be polarity of scanning. change up to down or right to left.


07-14-2010, 08:48
I'd say it was positive blank or negative blank selection.

07-14-2010, 09:00
Thanks Doc.

Can u explain to me what that is?

07-14-2010, 09:32
TTL lasers can be either on or off (no dimming ability). Some TTL lasers need a 5v signal to switch them on, some, some need a 5v signal to switch them off (blank). This second configuration is quite dangerous, as if the input modulation signal was to become disconnected; the laser will switch on at full power.

I'm guessing that your projector gives you the choice to suit different TTL DACs (the DAC: Digital to Anologue Converter)is the interface box between your computer and the laser projector), though as it has an anologue option; that would be the prefered mode.

Analogue lasers are able to adjust their brightness relative to a modulation signal of between 0v and 5v.


07-14-2010, 09:38
Thanks again doc,

I looked inside the projector and the laserdriver is set to TTL...should i set it to ang?

07-14-2010, 18:16

if you look at the picture he posted, there is a dedicated switch for TTL+/TTL- and analog. The ox+ and ox- is next to that.

my guess is still for scanning reverse.


yes, ideally you would want it set to Analog. this provides fading capabilities. TTL is either full on or full off. Analog provides a "ramping" brightness depending on the input signal


07-15-2010, 03:59
Surely the best way of finding out, rather than us all sat here guessing, is to just plug it in and move the switch and watch what happens.

07-15-2010, 08:18
So it does :o could also be an option for float high, ground to blank?

My thinking here is to do with the 'O' the international symbol for 'off' (blank)?

^^ +1 what Norty said ^^