DIY Driver Circuit question

I'm starting on the laser building hobby (from buying already built lasers), and decided to start with some diodes (Red, I expect) that came from my old DVD-RWs.

I have no driver circuit or way to provide the current amperage without frying the circuit and no advanced knowledge of electronics. What I do have are breadboards, resistors and capacitors.

Is there any way of making a basic circuit using only simple components in order to test my diode?

http://laserpointerforums.com/f67/laser-driver-can-done-rog8811-87507.html

Sounds like all you need more is an LM317 regulator and you're set:beer:
I made a laser using this circuit and it works well. (it's the white link in my signature)

Photonz said:

http://laserpointerforums.com/f67/laser-driver-can-done-rog8811-87507.html

Sounds like all you need more is an LM317 regulator and you're set:beer:
I made a laser using this circuit and it works well. (it's the white link in my signature)

Click to expand...

Awesome, I'm going to get a LM 317 and do a test case. I hope I have not destroyed them with the extraction process.

Well you don't need a 317 to test. You have resistors you said right? And a breadboard? Your good to go no matter what voltage you have coming in. Just set up a voltage latter! All you need is say any more than three of the same resistors. let's say you have a 10v supply to make this easy to understand. Now if all the resistors are at the same values say 10ohms take one resistor put it in line/series with the other and so on now say you have 5 10ohm resistors in line now jump one end to positive 10V and the opposite to GND now you have successfully made a voltage latter! Now if you test your voltage from one end to the other you have 10V+ now it's simple you have 5 resistors so that's 5 pieces! each step of the latter will drop exactly 1/5th of your input. So your start is 10v+ test one resistor down you will have 4/5ths of 10 so at that point you will have 8V+ move one more resistor closer to GND and then you got 6V+ Then 4V+ Then 2V+ till 0 at GND. So hook LD at the 2V spot. Now this latter works in division so if you have two resistors same values, then in middle will be 1/2 at 5V+ and if you had 100 resistors then every step is a 1/100th of 10V so each latter step is .1V drop. Now current limiting wise you can't count how many resistors from positive you are you must take in effect every one in the circuit. Now I recommend starting at a higher value resistor latter so you don't fri it. Remember this is a voltage latter not current latter. The current capability is the same throughout the entire latter. So a 5 step 100k ohm latter will allow much less current then a 5 step 10ohm latter. Keep that in mind! Have fun!:sold:

Ignore Nissan20det's post entirely. This is not an appropriate way to drive a laser diode.

Yes Ignore me if you like. but your new to electronics and this is the way to test a laser with the stuff you have. Safely! you would have no problem what so ever doing it this way. and its a good learning experience.

And by the way rh I never Once said this is the appropriate way to drive a laser. All I was getting across is he does not need to go out and get a lm317 regulator he can do what he wants without it the exact same way as if he had it. He wants to test the LD

Wrong. Nissan needs to do some research of his own.

It's not very well tolerated around here when people talk out of their @$$ and give members blatantly awful advice.

This is a ridicules conversation to be having, a LM317 is like 50 cents and direct driving a laser with just resistors is a BAD idea....

Nissan20det:

1) "Voltage ladder" assumes all rungs are in use. You're referring to a voltage divider.
2) Laser diodes are current driven, not voltage driven.
3) Voltage dividers have very high output impedance, making them useless for driving all but the smallest of loads.
4) "Just testing" might warrant the use of a single current limiting resistor. A voltage divider is not the correct configuration for this task. You are effectively putting a resistance across the load which serves no purpose and just wastes power.
5) If someone asks how to run their laser, and you give them instructions, it is implied that you believe your instructions are appropriate. Saying "I didn't say it was appropriate" long after the fact does not absolve you of the bullshit post.

-3

Yes, listen to Cyparagon. All you need is a
single resistor of the correct wattage and
value.

V = Input voltage
Vd = Voltage drop of the diode
I = Output current
R = Resistance value

R = (V - Vd) / I

Red diodes drop 2.3 - 2.5V
IR drops 2.0V
Violent diodes drop 6V

100mA (0.1A) is a good current for testing to
get writing diodes above threshhold. 40 -
60mA for reader (DVD-ROM) diodes (5 -
10mW)

Say you are using a 5V phone charger as a
power source. Plugging in our values, for a
red DVD writer diode we get:

25Ω = (5V - 2.5V) / 0.1A

5V won't work for BluRay diodes (violet)
since the voltage drop is 6V, which is more
than our 5V phone charger. For that we
need 9 - 12V.

60Ω = (12V - 6V) / 0.1A

Make sure the resistor is not wirewound. For
an LM317, everything gets easier since the
voltage will always be 1.25V and the diode's
voltage drop doesn't matter.

12.5Ω = 1.25V / 0.1A

The Lightning Stalker said:

Red diodes drop 2.3 - 2.5V
IR drops 2.0V
Violent diodes drop 6V

Click to expand...

I'd hate to have an encounter with one of these "violent" diodes.