Dilda Schematic!!!

Kage said:

...only the newest ones seem to have the component numbers silkscreened on the board. What, crushed pot?

Click to expand...

Thx for the feedback
I was trying to figure out why the adjustment screw for the pot looks so.... well, crushed, lol...

Traveller said:

[quote author=Kage link=1234431525/0#10 date=1234585291]...only the newest ones seem to have the component numbers silkscreened on the board. What, crushed pot?

Click to expand...

Thx for the feedback
I was trying to figure out why the adjustment screw for the pot looks so.... well, crushed, lol...
[/quote]

From the picts in your link, the pot looks to be in perfect condition, I can see the adjustment slot - it's just a cheap, open type trim pot, the trick may be finding a tool to adjust it with :

Great job and nice photos guys!

Originally, which consumption of  the  dilda driver with two RCR2?

Hug,
Andre

Kage said:

...it's just a cheap, open type trim pot...

Click to expand...

Ahhh... understood. What else should I expect for that price range...

Kage said:

My guess for the op-amp is a TI TLC2272 Rail-rail - Just now received some in the mail from Digikey.  I have 2 bad Dilda boards, and one of them definitely has a bad Op-amp as well as both have blown PNP transistors.  The test will be to see if I can repair these with the parts I just got.  If so, then we can be pretty sure this is all correct.   What clued me in to the op-amp was that one of mine has a suspicious symbol of texas stamped under a number 272...


Edit:
It worked!  Both boards are working.  
It is definitely the right Op-amp or at least a direct replacement, and the  PNP I got, a 2SB1073 (20V, 4A, 1W, Mini-power) - seems to work okay as well.  So, now I have 3 newer, working driver boards and an older "working" driver board, and no use for them, LOL.  ;D

Click to expand...

Nice to hear you were able to fix them!

What happened to the lasers those boards came out of?

Originally, which consumption of the dilda driver with two RCR2?

Click to expand...

At 6.0 volt battery supply, roughly 300 mA.

Benm said:

At 6.0 volt battery supply, roughly 300 mA.

Click to expand...

Thanks!

@Kage

As you disassemble the Dilda driver, you could measure the current supplied to the diode using Laser Diode Driver Test Load circuit?

According to Benn, the driver with the diode at 6V consumes 300mA. I would like to know what the current applied to the diode! That is, the efficiency of the driver.

Hug,
Andre

andrelcg said:

@Kage

As you disassemble the Dilda driver, you could measure the current supplied to the diode using Laser Diode Driver Test Load circuit?

According to Benn, the driver with the diode at 6V consumes 300mA. I would like to know what the current applied to the diode! That is, the efficiency of the driver.

Hug,
Andre

Click to expand...

Almost all the current IN is applied to the LD. About 10-15mA are used up by the rest of the circuit. So efficiency is dependent on battery voltage, and is worse as input voltage increases.

If R1 is reduced to 3 ohms or less, the circuit regulates just fine with those green 3V DX batteries.
http://www.dealextreme.com/details.dx/sku.932

This produces a little less heat than the 3.7V batteries, which will regulate without changing R1.
http://cgi.ebay.com/Juice-Brand-Rec...43287050QQcmdZViewItemQQptZLH_DefaultDomain_0

Kage said:

[quote author=andrelcg link=1234431525/16#22 date=1234746583]@Kage

As you disassemble the Dilda driver, you could measure the current supplied to the diode using Laser Diode Driver Test Load circuit?

According to Benn, the driver with the diode at 6V consumes 300mA. I would like to know what the current applied to the diode! That is, the efficiency of the driver.

Hug,
Andre

Click to expand...

Almost all the current  IN is applied to the LD.  About 10-15mA are used up by the rest of the circuit. So efficiency is dependent on battery voltage, and is worse as input voltage increases.

If R1 is reduced to 3 ohms or less, the circuit regulates just fine with those green 3V DX batteries.
http://www.dealextreme.com/details.dx/sku.932

This produces a little less heat than the 3.7V batteries, which will regulate without changing R1.
http://cgi.ebay.com/Juice-Brand-Rec...43287050QQcmdZViewItemQQptZLH_DefaultDomain_0

[/quote]

Thanks...

Good efficiency!

So, in normal condicions, any increase up to 6V will be heat dissipated?

Hug,
Andre

Now to get the rest of the dilda family and see if there using different driver for either
Their 405nm or their I.R.'s ;D cause I'm betting the change in the components is in relation to
universalize the driver to the diode of different nm. That is a good thing as the price could potentialy go down and power go up.

so... what would I do to mod this to go past 200mw?

bombsight said:

so... what would I do to mod this to go past 200mw?

Click to expand...

You could try this mod.  
http://www.laserpointerforums.com/forums/YaBB.pl?num=1233834330/0

Hug,
Andre

Kage,

Awesome job on the schematic! My dx200 came with a shorted PNP. I replaced it with a through hole PNP soldered to the surface. I originally soldered a 10 ohm resistor in parallel with the 6.8 ohm resistor. I ran this way for a while. Then I removed the 10 ohm and soldered in a 3.9 ohm in parallel with the 6.8 ohm resistor. So, now I only drop ~0.75 volt across the input resistor instead of ~1.1 volts. This gives a little more headroom for the regulator to work. It regulates my ~0.29 A pretty well down to a 5 volt input now.

I would give a bit of warning against lowering the value of the 6.8 resistor though... even in proper regulation, the output transistor needs to dissipate ~300 mA multiplied with the voltage it has to drop - which increases to unsafe values if you power it from 7.2 volts.

I reckon the 6.8 resistor is actually a late addition after they found out the output transistor would fry without it. Ofcourse, using a beefier transistor (as is done in the higher powered green DX AAA lasers) is the far better alternative, but they chose not to.

Benm said:

I would give a bit of warning against lowering the value of the 6.8 resistor though... even in proper regulation, the output transistor needs to dissipate ~300 mA multiplied with the voltage it has to drop - which increases to unsafe values if you power it from 7.2 volts.

I reckon the 6.8 resistor is actually a late addition after they found out the output transistor would fry without it. Ofcourse, using a beefier transistor (as is done in the higher powered green DX AAA lasers) is the far better alternative, but they chose not to.

Click to expand...

Good warning for anyone running from 7.2 volts. I'm still using the 2 x 3 volt CR2's.

Looking at the main dc link voltage of the DX200 circuit:

My 6.0 volts: 6 volts - (2.5 ohms x 0.3 A) = ~5.25 volts

Using 7.2 volts and 6.8 ohm resistor: 7.2 volts - (6.8 ohms x 0.3 A) = 5.16 volts

Using 7.2 volts and 6.8 ohm in parallel with 10 ohm resistor: 7.2 volts - (4.05 ohms x 0.3 A) = ~5.99 volts

The higher the DC link voltage the more power the transistor has to disipate.

Benm said:

Nice to hear you were able to fix them!

What happened to the lasers those boards came out of?

Click to expand...

Thanks. Two are Bluray, two are still red, but with boost regulators for better efficiency. ..

Only, I have just been testing a LDO linear regulator that is cheaper and better than my boost driver! I'm pretty exited about this one. I will be posting a schematic of it soon...

CHP said:

Kage,

Awesome job on the schematic! My dx200 came with a shorted PNP. I replaced it with a through hole PNP soldered to the surface. I originally soldered a 10 ohm resistor in parallel with the 6.8 ohm resistor. I ran this way for a while. Then I removed the 10 ohm and soldered in a 3.9 ohm in parallel with the 6.8 ohm resistor. So, now I only drop ~0.75 volt across the input resistor instead of ~1.1 volts. This gives a little more headroom for the regulator to work. It regulates my ~0.29 A pretty well down to a 5 volt input now.

Click to expand...

Thanks for the encouragement! Great you were able to fix it see how it can be made to work! I think at least one of mine had a shorted PNP when it arrived as well - doesn't say much for quality control :

Yea, that big resistor can certainly be tweaked for less power across the trany, and don't forget there is a total of 2.25 ohms in series with the PNP that also drop voltage. So, @ say, 300mA, R24 and R17-R18 will drop an additional .68V away from the PNP. There is also about 1 ohm of internal resistance in 2 of those CR2 batteries for another .3V drop - so there is a whole volt used up right there! Because of all these resistors, the range of regulation depends a lot on the current you set the pot to - if it's set at 400mA instead of 300mA, things change a bit... :-?

So, if you add up all the voltage drops, and allow the PNP 1.5V C-E with battery at full charge, set R1 accordingly for your battery type and LD current, the blasted thing should stay in regulation! I just wonder if it's easier to tweak the resistor "empirically" than trying to calculate it... ;D

- Or a spreadsheet could probably be made to calculate it closely enough with a little testing..