QS FB3 4,2v on modulation, NOT 5v :(

[norty303]

Jors, you are doing it wrong if you are using a multimeter, regardless of where you are measuring.

For a start, you haven't told us how you are generating the 'full on' signal in the software.

this topic was done to death some years ago, on an FB3 thread which had many pages.

Essentially, the FB3, even when on 'full power' has a period each priocessor cycle where it does 'housekeeping' in the processor. This means that for a very short period, it is off. So your measurement is only an average of the voltage on the pins, not the peak.

If you are using a pattern to generate your signal, then you may also have other 'off' periods which will also reduce your average voltage reading. The LaserMedia test pattern is generally considered to be the pattern with most 'on' time if you are using a test pattern, but still won't give you a peak voltage on your multimeter.

So, in summary, you either need to get an oscilliscope, or stop fiddling, as you could actually be adversely affecting performance, particularly by reducing your usable bandwidth for modulation.

[jors]

Many Thanks Norty
Sorry, this is my first projector. Test pattern I'm using is white cone at full power.
Ok, I understand...and yes, I've noticed more power output but less modulation bandwidth, specially noticeable on fades & color mixing (seems to be "less colors palette").

So, summarising please...do you recommend re-adjust drivers for full power, say...at 4,5V?? (voltage applied with LAB PSU)
Many thanks!!

[norty303]

I would put it back where it was personally, but others here might suggest that you could 'optimize' it over the factory settings.
I'd allow a little for voltage drop on the cables and make them all the same on the drivers.

[m0f]

I typically use a single static targeted beam set for 100%, to set my drivers. May not be perfect, but have never had a problem, and in theory the fb3 will never output a higher output than this. My theory is whether it's 5V or 4.5V, it doesn't matter when setup this way, as I set my drivers for the output I need to balance out the projector for my preferred white. Then again I'm not overdriving my diodes to the bleeding edge, so even if it ever did get 5V directly applied to the ilda input and the diodes were driver a tiny bit harder, it wouldn't really matter all that much.

[jors]

Many thanks Norty, M0f, learning a lot here on PL, thanks again for this

[planters]

Also... you don't need to see 5V on the modulation lines; most, if not all drivers provide full current / saturate with ~4.5-4.7V applied to the modulation input.

I don't want to try to find the relevant posts from years ago if the answer is generally known. The drivers I am using are quite linear and based on my power meter the laser output at 4.5V is very close to 90% of the output at 5.0V modulation. I set up the lasers with a bench power supply providing the modulation input and I later balance the colors with the software in Beyond. I had always assumed the 100% setting with a "white" projection was 5V to each laser if the color balance was also 100% in each channel. In addition, I assumed that these signals were slow enough and the current low enough that the voltage drop along the cables was negligible.

I am also building a DPSS laser that due to the high current requirements is being driven with a Wavelength Electronics 10A driver. The pumps are fully driven @ 7A and so there is a current limiter set not to exceed this, yet the driver will reach this @ 3.5V modulation. If the green channel is set to 70% max will this not be the maximum modulation signal?

[norty303]

the voltage drop along the cables was negligible.

Depends on the length of your cables and the quality. Some ILDA cable I bought from Goldenstar had enough resistance over 50m that I couldn't get 3.7V out of it to disable my interlock, which didn't say much for the mod lines!

[dave]

Depends on the length of your cables and the quality. Some ILDA cable I bought from Goldenstar had enough resistance over 50m that I couldn't get 3.7V out of it to disable my interlock, which didn't say much for the mod lines!

MMM, I found this out when shopping for the ILDA I just had delivered. The first sample was dirt cheap, but 50Ohm's down each conductor, down each pin! The stuff I received cost many times more, but less than a ohm

Looking good Jors!