Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers



Analog modulation with Flexmod P3

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
Howdy all.

I'v been doing some reading on the Flexmod and just can't get my head around setting these up and more so using the analog modulation.

I will be using the Flexmod to drive a 445nm diode in a lab style set-up.
From what I understand I need to set the start amp start point and max point. I guess that I hook it up to a test load and my PSU(it's a 12V5A small PSU) and 0 Bias sets the low point and the Gain the high point?
I may be wrong here, if anyone has set these up for non-portable adjustable use it would help to have input.:D

Now what I'm really having troubles with is the Analog Input and how to use it. My idea is to make a small control box that houses an on/off switch and a potentiometer to control the power output of the laser.

My question is what kind of potentiometer should I use? There are so many with different values i'm not sure how to choose.

Also how do I hook up the Mod+ to create that control? Does the positive or negative leads from the driver feed through the potentiometer? I think i'v seen photo's of the Mod+ lead going to the center wiper of the POT, but didn't see if either of the other two wires(+ & -) went to it as well.

Thanks all for your help. I'v almost got it all set up and will post pictures when it's all done.:beer:
 



MadEye

New member
Joined
Aug 6, 2011
Messages
129
Points
0
I also used an Analog Driver to be able to set my Labby from about 7mW to 1W :)

I wired it like that:


So you can set the modulation voltage exactly from 0-5V with your pot.

To determine the resistance of your pot you have to measure the resistance of the modulation port of the driver... Im not sure how I did it (Could check it tommorow) but I either used 10x or 1/10...^^ Your keyword here is "voltage divider". Just googel how to get it linear while loaded or something like that...

Its way to late here, need to go to sleep now... I can provide you with more details tommorow, with my PC instead of iPhone from bed... ;D
 
Last edited:

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
Thanks MadEye. The picture helps alot, really the way I learn the best. On the Flexmod it only has the one point for M+ so i'm still confused where the second (-) comes from. Also in the instructions for the driver it tells you to short the TWO mod wires....again there is only the M+ point.
Have you used this particular driver before? It says on the Flexmod manual that it has an "input impedance" of 99KOhm.
 

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,595
Points
113
The negative MOD lead is the same as the negative power lead. Input impedance is a measure of how much it will cause the signal to sag. This should be at least 10k for most DACs. The higher, the better.
 

MadEye

New member
Joined
Aug 6, 2011
Messages
129
Points
0
So I just checked my laser and the Drivers modulation resistance is about 10kOhms, and I used a 1k Pot to get nice results. If i turn the pot to about 50% I get about 2.4V, so its pretty nice.

When I build it first I took 100kOhm (Got the 10x rule wrong^^) and at 50% position the modulation voltage was already over 4V.
 

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
Thank you both for your help. So if i'm getting this correct I need a 1K Pot and some kind of 5V regulator along with my on/off switch should be all I need in my little controller box.

I need to find myself a short class on general electronics at a community college or something. I'v got all the hardware designing down pat, it's only when I decide I want it to have electronics in it that I begin to fail:undecided:
 

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
Needed thread and great replies- +2


thanks guys

hk
 

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
These are great little drivers! Stable, high amperage, safety features. There are quite a few talks on how to use them in a handheld but surprisingly not much discussion on using them in a lab style set-up.
The modulation is what I really had questions about, there is little to no information on how it is set-up in the way I would like. Usually just mention that it is analogue modulated. I would guess that usually that Mod+ wire is just plugged into a DAC or something and modulation controlled via a program but not a hands on POT.

If i'm able to get it working i'll post pictures(it always help make things a lot clearer for me when I see it set-up) I still need to find the correct 5V regulator and then set the driver for it's stand-by and high end.
 

MadEye

New member
Joined
Aug 6, 2011
Messages
129
Points
0
I think you could even take a 10k Pot since the flex mod appears to have almost 100k. If you set it up just try a few pot settings like 25%, 50%, 75% and check if its also that much voltage of 5%... You could buy a few cheap small ones (not for the final build) to test out which one performs best.

Actually I came across this topic because Im thinking about using an analog driver in my 2W arctic build and add a pot to be able to set it from 0 to 2+W... :D To bad there is no boost drive with analog modulation... The options for me are either 3.7V single cell or 2 3V cells... I dont want to also have 3.7V small cells around here and I also think they would start dropping current pretty fast as soon as they cant provide the voltage drop...
 

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
I'll try some different pot's....I have a small breadboard(i think that's what they are called) We'll see if anyone else has experience with these drivers. This shouldn't be that difficult, I just like to get things all in line before I start running power. Another addition that would be nice to the control box would be an amp or volt meter that would show the rise in power some way.

On PL and here i'v found some great photo's...mostly by Andy....of these drivers driving up to 4 diodes at once, using some resistor between them. Again though, no discussion of a manual analogue modulation.

I would like to keep this thread devoted to non portable builds with the Flexmod P3 though. There are some very good threads on using the driver in portables.

http://laserpointerforums.com/f51/how-set-up-flexmod-p3-handheld-laser-56572.html
 

MadEye

New member
Joined
Aug 6, 2011
Messages
129
Points
0
All portable builds just dont use the modulation.

This thread is about modulation (actually not even the way it should be used) and how to use it to be able to manual change the output with analog modulation. And there is absolutely no difference in using them in a labby or a handheld If you want use a pot to regulate the output.

If i find some 3.7 to 8V step up regulator I would acutally just build it in my Arctic 1:1 like you show it here :p
 
Last edited:

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
That's true...I just don't want it to stray to far off subject.

I think analogue modulation would be a great addition to a handheld if you can find a way to cram it all in there;)
I welcome any pictures of your build with the pot addition, these drivers are great, even if to large for many handhelds.
 

Cyparagon

Well-known member
Joined
Sep 12, 2007
Messages
9,595
Points
113
If this won't be driven by a signal, you can get away with a lot more. You can use virtually any 5V regulator. The choice of pot only really determines the linearity of response. 10k is a good choice. Anything between 1k and 100k will be peachy. 100K uses less power, but is slightly less linear. Here's a plot. (for imput impedance of 100k using Thévenin's theorem)

 

Attachments

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
MMMM....That help explain a bit, thank you. So it seems that the choice is not as crucial but as MadEye said with his 10x rule for testing we can zero in on the most appropriate pot to use. I do have a 100k in stock but I think i'll get the 10k to make it right.

So to create what I have in mind. The controller box with pot and switch, thanks MadEye for the graphics!...should look like this?
[/IMG]

Thanks to everyone for their help. I'm learning slowly but shurly about electronics with all your help.
 

532 with Envy

Well-known member
Joined
Jun 19, 2010
Messages
1,490
Points
63
Okay so I wired up the driver and hooked it up to my diode. I still haven't built the modulation box but wanted to see if it would just fire up without it.

I powered it up, waited for the interlock, got a quick flash of light and then the RED light came on on the driver. I have one wire coming from the mod+ but didn't hook it up because I'm really not sure what to hook the negative line of my 5V supply to?:thinking:
I tried hooking up the negative for the 5V PSU to the negative lead I have going to the main PSU off the driver and the positive off the lead from the mod+(not sure if this will work) Maybe if I short the MOD+ wire with the (-) out from the driver?

Does anyone have experience working with these drivers? Please help!


EDIT: Okay I did a bit more reading over at PL and found that I may need to connect the interlock pad to the V+. I did this and the diode comes on now, but right away. I guess the interlock is the 7 second delay. So one more step closer I hope, now to see if anyone has any input on the modulation hookup again....I just want to be sure. The flash from the diode when I didn't have the interlock connected gave me a good scare that I may have LED'd it, but all is good.

From a PL discussion..."Did you connect the interlock connection to v+. If you don;t do this the red led will stay on and you'll get no output other than a brief flash at the beginning. You diodes may be ok as the interlock circuit was in place."
http://www.photonlexicon.com/forums/showthread.php/15459-Just-blew-4-diodes!!!?highlight=flexmod+red+light
 
Last edited:

hakzaw1

Well-known member
Joined
Apr 2, 2009
Messages
9,840
Points
113
imma takin' notes


:pop:

Jordan did a portable .. I am sending him my diodes,copper module&HS and a p3 to wire up for a dual 445.

From seeing his and reading this thread I will do the next one myself- I plan to have two duals just to see the diff between cubeing and knifing.

then they go into one color sats.

Its sez QS will run six PJs- so I need more....any body need a qs fb3? $498 +ship- getting more in hand friday- (sry for spammin'):eg:

hak
 




Top