I am hoping you guys can help me because I am about ready to give up. I can't figure out what I am doing wrong. I checked my circuit using a test load of 4 diodes and a 1 ohm resistor. I checked mA across the resistor with my DMM and it is showing 160mA using a 6.5ohm resistor. I hook up the 16x diode I harvested and pressed into the module and the only thing i get is a really dim dot. The LM317 module is rather warm as well. If I swap out the resistor in the circuit to a higher one to achieve around 25mA, my blu ray diode lights up just fine. I tried an open can diode from a 16x burner as well and only get the same results....what is it that I am doing wrong? When at lower power levels the LM317 stays room temperature.
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frustrated, what am I doing wrong?
- Thread starter ashenfang
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Whats your power source? whats in your LM317 circuit?
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Did you remember to SHORT the Cap? If not Your diode is LED. 9v might not have enough current(sometimes they do & sometimes they don't).
Care to ealaborate on how you exactly do the measuring?
You seem to be a little confused, because CURRENT is measured IN SERIES with the
circuit. Or are you, in fact, measuring the VOLTAGE DROP across the resistor, and
calculating the current from there?
Also, those 9V blocks are really bad when you need current delivered.
They're really nothing more than glorified and stacked up button cells.
You'd be much better off using Li-Ions, or even AAs.
Other than that, I suppose your diode is dead.
I am measuring how it was suggested to me by another member on the forums. Energize the test circuit ans then place the test leads across the 1 ohm resistor. Put the meter in mV and read what the meter displays. Depending on the resistor value the numbers will change the reading. He explained to me this will give the approx. Current to the LD. Sounds like i am not doing it right so if you could explain maybe i will quit frying diodes.
For clarification this exactly how the circuit is wired
For clarification this exactly how the circuit is wired
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Your circuit looks fine, and it seems like you got the current measuring method right, too.
Remember, some capacitors (the cylindrical ones) need to be installed the correct way around (+ and -),
they are marked on their negative pole side.
Face it, you killed that red diode somehow.
Remember, some capacitors (the cylindrical ones) need to be installed the correct way around (+ and -),
they are marked on their negative pole side.
Face it, you killed that red diode somehow.
Well i am not sure what is going on then. The polarity of the capacitor is correct and you said the circuit looked fine. Im stumped. I love building things and i am usually pretty good at it but this is just been a head ache. On a side note. When increasing current output is it normal for the regulator to get pretty warm? The only other thing i can think of is that i just have two bad diodes. They did come out of used untested drives. I think i am going to ditch the 9v and try 5 AA batts until i can get 2 3.7v lithiums.
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Your diode didn't light?
Man.. red got forward voltage of 3.5v. LM317 dropout is 2.5v (or more: don't remember) but 9V is for blu-ray diodes that have a high forward voltage (like 6.5v). You should put lower voltage on the driver..
Man.. red got forward voltage of 3.5v. LM317 dropout is 2.5v (or more: don't remember) but 9V is for blu-ray diodes that have a high forward voltage (like 6.5v). You should put lower voltage on the driver..
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That's totally unnecessary, the lm317 takes care just fine of any excess voltage,
dumping it as heat, no worries there.
qumefox
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If your using a test load like this and actually seeing 160mA across the 1 ohm resistor, then i'm not really sure why your killing diodes.
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@anselm
I've simulated it, and it does not. Me and the simulator may be wrong, tho.
I've simulated it, and it does not. Me and the simulator may be wrong, tho.
Care to elaborate?
I have measured it from my running circuits, with test load and different LDs so .....:na:
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@anselm
oh ok, sorry. you win, me lose. You are superior. hahah
I just complained about it, because LM317 has two modes, CV and CC. I got a little worried because some people read on sites that "a laser driver can be done with a lm317" and they go straight to the datasheet, that includes the CV diagram. I didn't know that all voltages could work with LD's but, the lower the battery, the weaker the laser goes, right?
I don't like LM317, sorry, so I don't know.
oh ok, sorry. you win, me lose. You are superior. hahah
I just complained about it, because LM317 has two modes, CV and CC. I got a little worried because some people read on sites that "a laser driver can be done with a lm317" and they go straight to the datasheet, that includes the CV diagram. I didn't know that all voltages could work with LD's but, the lower the battery, the weaker the laser goes, right?
I don't like LM317, sorry, so I don't know.
I direct drove the diode with 3 volts and it lights but its a very dim red. So im confused, are you suggesting that the lm317 is wired wrong? Do i need to drop the voltage and will using 5 AA batteries help with current draw? Im pretty sure this diode is toast. I have a couple others but they are the open can flat type with 4 wires and wont fit the housing. Maybe i should just give up and buy one.
