Modifying Q-switch driver for external modulation

[Laserman532]

hmm..

manual states 6 - 12khz rep rate...

but elsewhere i've seen Laserman quote a minimum rep rate of 10khz, all the way to 25khz ?

it depends on what driver you have. there are also jumpers on some drivers that allow different ranges...these lasers run well at 15khz

[aijii]

We have the 1027-25, as discussed in this thread. I don't have it in front of me at the moment, so can't open the driver to check for jumpers. Doesn't appear to be any mention of selectable ranges (via jumper) that i've seen in the manual...

it depends on what driver you have. there are also jumpers on some drivers that allow different ranges...these lasers run well at 15khz

[weartronics]

We have the 1027-25, as discussed in this thread. I don't have it in front of me at the moment, so can't open the driver to check for jumpers. Doesn't appear to be any mention of selectable ranges (via jumper) that i've seen in the manual...

If you're bored one evening, you can draw some of the logic to find the oscillator (or insert your own modulation signal). But first, I would use a directional coupler (or even just a 100X probe in parallel with the load) and turn the blue potentiometer very slightly to see if it effects the oscillator frequency. I think there's a good chance that it will.

[Laserman532]

If you're bored one evening, you can draw some of the logic to find the oscillator (or insert your own modulation signal). But first, I would use a directional coupler (or even just a 100X probe in parallel with the load) and turn the blue potentiometer very slightly to see if it effects the oscillator frequency. I think there's a good chance that it will.

i assure you the internal pulse generator will operate from 75 hz to 75khz, it came from my eyeballs to this keyboard.

[weartronics]

i assure you the internal pulse generator will operate from 75 hz to 75khz, it came from my eyeballs to this keyboard.

Are we talking about NEOS N31027-50DM (perforated black cover, found inside older Z-folds) or Crystal Technology CT1027-25 (gold anodised cover, found inside newer Z-folds) here? The older NEOS drivers seem to be general purpose and very capable, while the newer Crystal Technology drivers seem to be OEM for Laserscope, with only the minimum necessary features available (i.e. limited internal modulation range, no external modulation input, and no FPS).

[Laserman532]

Are we talking about NEOS N31027-50DM (perforated black cover, found inside older Z-folds) or Crystal Technology CT1027-25 (gold anodised cover, found inside newer Z-folds) here? The older NEOS drivers seem to be general purpose and very capable, while the newer Crystal Technology drivers seem to be OEM for Laserscope, with only the minimum necessary features available (i.e. limited internal modulation range, no external modulation input, and no FPS).

external card necessary - i will supply no information publicly as unqualified hands may be reading it. you know which card i am talking about.

[aijii]

Hold on - I thought the Crystal Technology CT1027-25 driver has in built FPS ?

[weartronics]

Hold on - I thought the Crystal Technology CT1027-25 driver has in built FPS ?

I don't think so. But since there is no way to hold-off the beam, there is no way to build up a giant pulse, so FPS isn't necessary anyway.

[uk-laser]

I don't think so. But since there is no way to hold-off the beam, there is no way to build up a giant pulse, so FPS isn't necessary anyway.

In the manual you posted it shows 2 modes - High RF mode which is pulsed and Low RF mode which is CW.
In my 'lil green uses the 1027-25 and the Low RF mode had been factory adjusted to have approx. twice the power out as the pulsed mode making High RF operating with Q-switching and Low RF mode being blocked. Going from Low RF mode to High RF mode will give you a big first pulse.

Rgds,
Robin

[weartronics]

In the manual you posted it shows 2 modes - High RF mode which is pulsed and Low RF mode which is CW.
In my 'lil green uses the 1027-25 and the Low RF mode had been factory adjusted to have approx. twice the power out as the pulsed mode making High RF operating with Q-switching and Low RF mode being blocked. Going from Low RF mode to High RF mode will give you a big first pulse.

That's clever, because I hadn't considered turning low RF up to full RF. It means that any FPS issues aside, the low/high RF input could be used for blanking! Now I am inspired to actually check for evidence of FPS.





This trace shows the first pulse after the RF low/high transition. It's bad news, but I can't see any evidence of FPS. So occasional blanking (e.g. at the start of a show) is probably OK, but I wouldn't advise using this driver for high repetition rate blanking (e.g. blanking inside frames).

Of course, it would be possible to keep the existing RF stage and design your own oscillator stage with FPS, but it's probably cheaper to buy a surplus driver with FPS.

If you're bored one evening, you can draw some of the logic to find the oscillator (or insert your own modulation signal). But first, I would use a directional coupler (or even just a 100X probe in parallel with the load) and turn the blue potentiometer very slightly to see if it effects the oscillator frequency. I think there's a good chance that it will.

While I had the driver out, I did this experiment for you. The blue potentiometer does effect the oscillator frequency as I suspected. In my tests, it is adjustable from ~17kHz (upper photo) to ~40kHz (lower photo). That disagrees with the specification (6kHz to 12kHz), but it's what I measured.