Cheap analog driver??

[logsquared]

Its hard to say exactly what their circuit is.... This simple circuit should give you a bias adjustment. Keep in mind the bias would be tied to voltage change and regulation of the power supply.

[absolom7691]

The interesting thing about this board is that there is no heat sink or high power FETs. It looks to me like there are three separate PSUs on the board that bring the voltage down so that the FET has to burn very little as heat when regulating the current.

[logsquared]

I just took a closer look at the board in the ebay add. Looks like 3 inductors on the board. Could be PWM on the outputs or PWM pre-regulation for a linear driver. Its hard to say really. It says rated for 500mw blue. That would only be .5A. Surface mount fets could probably handle that as a linear reg.

[WolfMax]

same board, this one says it is TTL
http://www.ebay.com/itm/637nm-638nm-...item35e07d6e61

That is because the advert is for both the driver and the laser module and it is the laser that is TTL (RL1000)

This one is analogo
http://www.ebay.com/itm/637nm-638nm-...item35e07d9df1

Again, this is for driver and laser but this laser is an analogue model (RL1000-A).
An analogue driver can be used for TTL lasers because the control software needs to be told what laser type you have. This will then dictate what signal modulation type the DAC is told to send to the laser driver. And as an analogue driver can accept any signal voltage from 0 to 5, simply switching between 0 and 5 is not going to be an issue. However sending a variable voltage to a TTL driver could cause some strange results

I also found the same modules (TTL/Analogue) can be obtained from GoldenStar lasers who are often reported by others on PL to be a good company to deal with.

[jeejeedr]

That is because the advert is for both the driver and the laser module and it is the laser that is TTL (RL1000)

A (diode or dpss) laser is not ttl or analog. It is the driver that makes it ttl or analog...

[Datsurb]

Just wan`t to skip in and point out that the "Anologo" word is different. I don`t know if this i a word they use for this driver, or if it is a typo. I have twoRGB blocs with the "ANALOGO" driver, and it actually does not modulate as expected. Insted of decreasing the current, it modulates the current on/off. This comes very clear when projecting graphics, but works quite well shooting beams.

When doing graphics the lines becomes more and more like dots, and not fading as expected. The drivers looks very much hand-modified as the soldering of some components are irregular compaired to most solderings. I have a spare driver in my workshop, and can provide som more detailed pictures, but that have to be after christmas.

The Analogo thing have been an issue for some threads here at PL before.

For me, the driver works fine, as i mostly do beams, and have other projectors for graphics. The 1W brick with this driver is not something I would reccomend, as the red LD have no correction, and lases like a tourch. Actually no way of fitting the beam on the mirrors of a PT30. I had to be a little creative and made a pinhole through aluminum tape in front of the brick to reduce unwantet splash of red.

[dkumpula]

Considering the relatively small price difference between quality drivers like Dave's, BBEs, badpips, Andrew's, etc., I don't understand why anyone would risk their diodes/builds on questionable Chi drivers. Spending an extra $12 here to ensure you don't otherwise handicap your projector just seems like a worthwhile investment.

David

[absolom7691]

Just wan`t to skip in and point out that the "Anologo" word is different. I don`t know if this i a word they use for this driver, or if it is a typo. I have twoRGB blocs with the "ANALOGO" driver, and it actually does not modulate as expected. Insted of decreasing the current, it modulates the current on/off. This comes very clear when projecting graphics, but works quite well shooting beams.

When doing graphics the lines becomes more and more like dots, and not fading as expected. The drivers looks very much hand-modified as the soldering of some components are irregular compaired to most solderings. I have a spare driver in my workshop, and can provide som more detailed pictures, but that have to be after christmas.

The Analogo thing have been an issue for some threads here at PL before.

This is what loqsuared suspected. PWM for each channel. That's why you're seeing the dots. That's also why I am seeing smooth modulation from 0~5V even though there is no 0bias. With PWM, you don't need it. I have already decided that I am not going to use these for my graphics projector. They are going in my lumia box. The work fairly well and I am not seeing any current spikes that would endanger the diodes. My lumia box is not using beam steering so 6 lumia ports will require 18 individual drivers. The savings will add up!

[flecom]

I ordered one of these and will be hooking it up to an oscope to see if it's just PWMing the lasers or really analog... I am leaning towards PWM which would make them pretty much useless

[absolom7691]

I ordered one of these and will be hooking it up to an oscope to see if it's just PWMing the lasers or really analog... I am leaning towards PWM which would make them pretty much useless

Well, useless outside of anything but statics.... Beamtables or lumias.