DIY Homemade laser diode driver

[ELE]

oh man you are great! look at those stuff it is really easy to understand i have to thank you a lot!

 

[Hemlock_Mike]

Gazoo --

You mentioned in an earlier post that the RS 25 ohm pot goes down to 0.3 ohms. that low reading is probably the test prod leads. Touch the test prods together and you will likely read between 0.3 and 0.5 ohms.
I point this out here because now that a bunch of you are working with low impedance circuits, you need to account for stray readings.

Mike

 

[Things]

yeah that's a good point mike! you will get losses somewhere in the circuit because everything isn't 100% efficient, even the capacitor can lose a couple of millivolts for you! the pot might loose abit of power, and the LM317 uses the power to regulate. so you have to take that into account as mike said.
good luck guys!

 

[Gazoo]

Well I am using a cheap meter, but it does register the same as a decent RS one I bought years ago. And it does zero out with the probes touched together.

Xenodius has the same rheostats and when measured with his dad's Fluke meter, he gets the same readings. The Fluke is a much better meter than any meters I have.

 

[-Witch-Doct0r-]

Just spent [highlight]£17.00[/highlight] = [highlight]$34.00[/highlight] on parts inlcuding the P&P not including the LD's or AixiZ modules...

I got:

50 - Capacitors
5 - LM317
10 - Potentiometers
25 - Resistors
25 - Silicon Diodes

Rekon that was a bit dear or not?

 

[Daedal]

;D ;D That's not enough for me... ;D

My orders are usually a bit more on the huge side

Although, that should be more than enough to make a few of these driver circuits

--DDL

 

[Comidt]

i just got my parts today
Yay!
I'm gonna build it tonight hopefully.
So, with the resistor you used, Daedal, the 4 0hm, what current do you get out, no pot?
Thanks
Jonno

 

[xgeek]

With a 4 ohm resistor the LM317T will be set to 0.312 mA
1.25/4 = 0.312 mA

I am using 5 ohms in my builds to get 0.250 mA

 

[Comidt]

Thanks
I got 2, 3,4,5 ohm resistors
25, 50 and 100 ohm pots
3 x lm317's
and 5 x 1n4007 diodes

 

[-Witch-Doct0r-]

I also brought this for random parts & spares approx 200 items

http://cgi.ebay.co.uk/ws/eBayISAPI....m=180155178115&ssPageName=STRK:MEWN:IT&ih=008

 

[laserrod]

Hey Daedal,
I didnt' know you you sold ready to use driver-boards

Do U have Photo of it you you can link me to yet?

 

[Gazoo]

Here ya go:

http://www.laserpointerforums.com/forums/YaBB.pl?num=1188850622

 

[Daedal]

-Witch-Doct0r-, that's a nice set of stuff... it's good to have extras like such in the off chance that you need one of them

Gazoo beat me to the link Hope you like it Laserrod.

--DDL

 

[Zax]

Daedal, Great job on the circuit explanation - however, you say the 1N4001 diode reduces the voltage to the LD but it's in reverse polarity (so is in fact an open in normal operation).

 

[Daedal]

Thank you Zax. Although, it's not an open circuit. It would be an open circuit if the diode was connected in the right polarity. That's why it works for reverse polarity protection.

For the 1N400X diodes to drop the voltage, you'd need to put them in series with the LD. That's something I had meant to fix in the guide several times before and kept forgetting. Thank you for reminding me.

--DDL

 

[toked323]

hey daedal i mad your ciruit here are some picts it looks sloppy but hey