Stan_Ham diode driver (analog)

[Anthony]

After showing my first projector on the forum i got several PM about the analog drivers i used.
http://www.photonlexicon.com/forums/...ead.php?t=6473

Some time ago i was looking for a simple driver for analog modulation of cheap opencan reds and bleurays.
Rob stanwax emailed me with a driverschematic of his dualdriver he was using in his small projector.
with some help of Rob (Laserwave.co.uk) i modified the driver and made a single anolog board out of it.

We know its nice when people help each other.
So here's the schematic and PCB for you all to expiriment with.

Enjoy!!

DO NOT SELL THESE COMMERCIALLY..

special thanx to www.laserwave.co.uk

The 300 Dpi files are in the downloadable zipfile.
http://www.hamond.nl/images/plaatjes...HAM_driver.zip

photo's are for showing only.








Partlist

Part Value
C1 100nf
C2 100uf
D1 1N4148
D2 1N4148
D3 1N4148
IC1 LM358N
IDLE 10K RTRIM64W resistor
LED1 power LED3MM led
MAIN 10K RTRIM64W resistor
R3 10K
R4 10K
R5 10K
R6 10K
R7 1K
R8 10K
R9 1R
R10 10K
R11 10K
R16 calculate for diode type
T1 BD437

[stanwax]

Anthony I love the name! Stan_Ham is mega!!!

Rob

[mophead]

Kickass, y'all.

This is *exactly* what i've been looking for.

Thanks again

[danielbriggs]

Could you by any chance post the board for the dual driver setup? As I'd be looking to buy/build two of the dual driver setups for some blu and red diodes.

Excuse my ignorance on this, but am I right in thinking these replace the current sources for the drivers of the diodes, and swap them directly with this circuit?

Also, am I right in thinking the diode would connect in the top right (at least for the single diode version), the +/- 6V on the left, and a connection to the FB3 on the SINGLEMOD point?
What do the Monitor points do? And what do the pots do?

Is this basically like the LavaDrive1 circuit? (or whatever it's called!)

Rob, do you have any of the dual diode boards, blank or completed PCB's made up to buy? No worries if not, I'll route one out myself, but it would save me a few hours.

Cheers,
Dan

[sugeek]

Thanks!

[stanwax]

Dan

Yes they will work exactly as you suggest. The monitor points are so you can see the diode current and... well.... monitor it With a 1R resitor the volts (or more accurately millivots) acrsoo the resitor will indicate the mA through the diode. The pots are for threshold and max diode current so you set the driver to keep the diode current dribbling just on the point of lasing. Then as the input increases you have maximum range between 0 and 5v on the modulation. The limitation of the board is based on the output transitor (in combination with the monitor resistor (R9) and the supply volts. I run this circuit in my RGB and the output transistor is a BC337 (good for 800mA) which is neatly in a to92 and does not need heatsinking for a single diode drive.
Yes I will be able to sort you either a pcb or a complete built board of the dual driver - this is actually as it first went to Anthony, he just trimmed one circuit out.

Rob

PS sorry i missed you yesterday give me a try this aft I will have my phone with me today

[Anthony]

Yes I will be able to sort you either a pcb or a complete built board of the dual driver - this is actually as it first went to Anthony, he just trimmed one circuit out.

I have replaced the BC337 for a BD437 that could be cooled better with a heatsink because i wanted te run a 500 mW 808 pump diode.
The bleuray diode at 60mw doesn't even get warm :-)
I added some small things and use different pots

The dual driver from Rob is a nice small board.. good layout and works great.. just watch his youtube videos.


my first TEST board without powerled and with the bc337.
different PCB routing.

[mixedgas]

eh, just one question. Where is the soft start?

Steve Roberts

[Anthony]

eh, just one question. Where is the soft start?

Steve Roberts

There is NON...
not everybody has the knowlegde like you....
feel free to improve the schematic and board.

its a PL project.
But keep in mind that is has to be obtainable for evrybody (no SMD and exotic EU or USA electronics)
Someone with basic electronics skills must be able to make te board.
Maybe in the future put in a lasorb.

there is no simple non SMD analog driver ("freeware") available yet.

[allthatwhichis]

Ahh, nice, so there is no requirement for me to be able to build one...

[Anthony]

Now that i think of it.....
Why would softstart be something we wan't?

It is better for the diode?
what about the DVD burners where diode's are used in and what about modulating the dioded like we do?
thats alot of fullpower ON OFF ON OFF.. so softstart there.

Would it really hurt a fast semiconductor/diode?

[stanwax]

Anthony
Steve is right and a softstart would prevent the diode being damaged by transients on the power supply as its turned on not as it is modulated. I have thought about this in the past but have not got round to implementing it and this circuit has worked for me with no probs in my RGB for 2 years. Ok I know that does not mean it cant have a problem....


Rob

[allthatwhichis]

Would that be the first place you would suspect if you had a faiure?

[Anthony]

Anthony
Steve is right and a softstart would prevent the diode being damaged by transients on the power supply as its turned on not as it is modulated. I have thought about this in the past but have not got round to implementing it and this circuit has worked for me with no probs in my RGB for 2 years. Ok I know that does not mean it cant have a problem....


Rob

Rob,

i can understand that a softstart is nicer on the diode when used in an non modulated form.

We use the modulation to turn on the laser.
Wen i power on the driver, the diode is off until i start modulating.
The powerled/caps etc are al powered on before modulation.

maybe i don't understand the concept entirely. :-)
i'm no electrocs expert like you guys

[stanwax]

The modulation takes place when the supply line is (hopefully) in a steady state, but during the power up nanoseconds spikes on the power supply line can provide the killer dose of electrickery that the diode cannot stand. So the modulation, no matter how fast does not (or should not) provide a spike but the PSU start could.

Rob

[Anthony]

The modulation takes place when the supply line is (hopefully) in a steady state, but during the power up nanoseconds spikes on the power supply line can provide the killer dose of electrickery that the diode cannot stand. So the modulation, no matter how fast does not (or should not) provide a spike but the PSU start could.

Rob

ok,

So C1 and C2 cant handle the nanosecond spike because they act to slow?

Maybe we could improve the driver as a combined PL efford.
Could be a nice solution for alot of people.
maybe something good comes out of the TEC controller topic.

having a nice tec controller and a nice diode driver should be a dream com true for alot of DIY people.

[stanwax]

I will get round to doing something about this but its not been that important in my list of jobs .
There are several ways to do it but slow ramp up of the diode current from cold start plus good input protection on the PSU connectio is the way to go.

Rob

[smogthemog]

I used a dual version of this Cct of Robs on my twin red/pbs set up on my ALC68. It worked a treat
Easy to set up as well.

[carmangary]

die4drive has slow start. you could take a look at it as an example of how to do it I suppose. I have wondered how slow start effects modulation speeds.

[stanwax]

Gary
As far as Im aware what you need to do is apply the slow start to the first diode turn on, therein afterwards the modulation should not be affected - or at least that should be the aim of the design. The Roithner EU38 has a real slow start on it and you can see the laser ramp up over about a second and a half but this has no modulation....
I guess what you need is to ensure the diode is held hard off during the power phase and remains in this state until the power has settled. Probably only needs a short time - maybe 100ms would be way more than needed so a couple of seconds should be belt n braces.
Like I said I will get round to looking into this but its at about 489th in the queue at present

Rob

[mophead]

If the power supply starting ( and suppling the spike) is the problem, why not just use either a timed relay or some type of opto to hook the driver circuit to the power circuit after the power supply has become stable?

Maybe yes, maybe no?

I know *just* enough about circuit design to get me into alot of real world trouble.

Just some thoughts.

d~

[mixedgas]

softstart is very useful on both diodes and scanners, most modern systems have it on both turn up and turndown, and there are cheap, power fail sensing chips, usually in 3 pin transistor package.

For hobby use, a simple relay across the diode, with some damping diodes across the relay coil and on the relay power will suffice. Mr Murphy comes to get you at showtime, not on the bench. I'll dig up the slow start schematics for the omni 150 argon and the 60X.

the 150 counts to 30 seconds using a 4040 cmos counter driving a mostfet, which costs about 75 cents, and the 60X uses a 555 timer and a relay.

A P channel mosfet defaults to on, so you just make its gate positive with it across teh diode to lite the diode.

It is especially wise to have your scanners wait till both supplies are at rails, older opamps can latch up when the negative rail comes up before the plus one.

Steve

[Pangolin]

Everyone might want to take a look at this. This is, essentially, a soft-start directly for the laser diode itself. It guarantees that, whatever happens in the power supply or the rest of the electrical circuits, spikes won't be able to get to the laser diode.

The Windows Media file is here:
http://www.pangolin.com/_Files/LASORB.wmv
There is an MPEG (lower quality, but larger file size) here:
http://www.pangolin.com/_Files/LASORB.mpg


Bill

[carmangary]

When will it be available and for how much moolah?

[Pangolin]

When will it be available and for how much moolah?

The LASORB IP has been available since late 2008 and is already incorporated into drivers of an aerospace company and also a really famous laser diode and fiber optic company for whom we would all know their names (but I don't know if we have permission to reveal that they use an outside vendor, so I won't mention their name). As the video says, LASORB is a collection of components, so these components can be placed onto a laser diode driver and work that way.

We are in the final processes of producing encapsulated parts right now, and these should be available within a month. We just have some more testing to do of the encapsulated parts. (Pangolin is a company that tests and tests and tests things before their release.)

The price is somewhere between $2 and $8, depending on the quantity, so it is quite reasonable. Certainly VERY cheap insurance for any laser diode!

Best regards,

William Benner