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11-24-2010, 01:54 AM #1
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Clickey
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DDL Circuit - Tell me If I'm doin' it right

So I am pretty clear on the laser diode situation but now I need a better testing method for my circuit. Unfortunately I do not have a mA reading on my multimeter, well I do, but it just doesn't work. (I think I broke it)

Now, in one of my previous posts I heard someone say "1.25 Vref" or something similar.

Also in this video by Styropyro he says to take 1.25 and divide by your requested output in amps. I don't know why 1.25 is used, but I do know how to calculate the requested output current. The question that remains is if I can test if my LM317 still works without a mA reader.

So this is the future circuit I intend to build I want you guys to tell me if it's all good.

To calculate RValue you need to do this
1.25 / desired Current = RValue
In my case for my future PHR - 803T diode it will be 125mA so
1.25 / 0.120 = 10 so my value for the resistor is going to be 10 -ohms.

I also have a few questions about another diode. The KES400A is the blu-ray diode found inside of a PS3. My friend is gonna give me his broken PS3 and I am going to take the laser out. I really don't have a need for the console as I am getting a XBOX.

So what should I run the KES400A at?

Last edited by Clickey; 11-24-2010 at 02:10 AM.

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11-24-2010, 02:15 AM #2
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anselm
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Re: DDL Circuit - Tell me If I'm doin' it right

You might wanna try and open up your DMM, see if it has screws.
There might be a 200ma (or something) fuse which you blew trying to measure
more than that. Replace.

You can still read current by using the voltmeter. Measure the voltage across
a known resistor in series with the circuit, there is a formula, but
I think if R = 1 Ohm than the mv you measure = the ma that flow.
But don't quote me on that.

Connection between points 2 and 3 on your switch seems unnecessary to me.
Other than that, it looks like i would work.
Hook up a LED you salvaged from some e-junk, see what happens.

EDIT:
It's 1.25V because that's the reference voltage of those lm317

11-24-2010, 02:57 AM #3
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Clickey
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Re: DDL Circuit - Tell me If I'm doin' it right

Quote:
 Originally Posted by anselm You might wanna try and open up your DMM, see if it has screws. There might be a 200ma (or something) fuse which you blew trying to measure more than that. Replace. You can still read current by using the voltmeter. Measure the voltage across a known resistor in series with the circuit, there is a formula, but I think if R = 1 Ohm than the mv you measure = the ma that flow. But don't quote me on that. Connection between points 2 and 3 on your switch seems unnecessary to me. Other than that, it looks like i would work. Hook up a LED you salvaged from some e-junk, see what happens. EDIT: It's 1.25V because that's the reference voltage of those lm317
Thanks for the help. Appreciate it. And yes the problem is the fuse. It got blown out. I need a 250v 200mAL replacement.

11-24-2010, 10:57 AM #4
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anselm
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Re: DDL Circuit - Tell me If I'm doin' it right

The "formula" I meant is properly called "Ohms law".
If you cannot find a 200ma fuse, you can use a 250ma one as well.
If you don't want to keep blowing them, use the 10A range on the dial and
the corresponding port for the DMM probe.
Only if you get readings < 0.2 A, then use the 200ma setting.

Last edited by anselm; 11-24-2010 at 11:02 AM.

11-24-2010, 04:39 PM #5
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Clickey
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Re: DDL Circuit - Tell me If I'm doin' it right

Quote:
 Originally Posted by anselm The "formula" I meant is properly called "Ohms law". If you cannot find a 200ma fuse, you can use a 250ma one as well. If you don't want to keep blowing them, use the 10A range on the dial and the corresponding port for the DMM probe. Only if you get readings < 0.2 A, then use the 200ma setting.
Yeah I know. My younger brother wanted to see it and well when I got it back it was not working. But I will get a replacement fuse today, so it will be good as new. I know about the other readings and stuff as well. You don't need to tell me.

11-26-2010, 03:09 AM #6
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Re: DDL Circuit - Tell me If I'm doin' it right

What should I do:

I am receiving a broken Playstation 3 in a few days from a friend who is getting a replacement. Now I can either extract the KES-400A diode and use that, or sell the PS3 for a bit of money and buy other diodes. I really want to build another PHR-803T laser for some extra practice. My first 2 PHR's burned out because a bad driver. So what should I do. Be completely honest.

11-26-2010, 10:42 AM #7
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anselm
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Re: DDL Circuit - Tell me If I'm doin' it right

Collect some (broken and free) DVD burners, and practice extracting and driving
those diodes for a while, untill you are comfortable enough to be able to keep
them alive consistently.
Only then shell out \$\$ for whatever diode you REALLY want.

11-26-2010, 03:02 PM #8
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Re: DDL Circuit - Tell me If I'm doin' it right

Quote:
 Originally Posted by anselm You can still read current by using the voltmeter. Measure the voltage across a known resistor in series with the circuit, there is a formula, but I think if R = 1 Ohm than the mv you measure = the ma that flow. But don't quote me on that.
I will quote you on that, since its a good approach. Personally i prefer to have the 1 ohm resistor in series with the diode, soldered in place. That way, you dont have problems with bad connections in multimeter leads that can cause the capacitor voltage to rise, and blow the diode when the connection is restored.

As for the multimeter fuse: I've seen them with 1 A fuses, despite the current range is only 200 mA. You could blow up the shunt if you run too high a current through it for some time, but as long as you immediately stop measturing when the meter goes over 200, a higher value can be okay.

11-30-2010, 11:32 PM #9
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Re: DDL Circuit - Tell me If I'm doin' it right

Quote:
 Originally Posted by Clickey What should I do: I am receiving a broken Playstation 3 in a few days from a friend who is getting a replacement. Now I can either extract the KES-400A diode and use that, or sell the PS3 for a bit of money and buy other diodes. I really want to build another PHR-803T laser for some extra practice. My first 2 PHR's burned out because a bad driver. So what should I do. Be completely honest.

Check what "As is" broken PS3s are going on ebay or craigslist for. I haven't looked lately but they were selling for about half the price of a new one last I time I checked. If that's still the case or you can get \$50+ I'd probably sell it and go buy a couple PHR sleds from Modwerx Shop. They're a whole 9 bucks each. Shipping will probably be about 5 bucks since they use priority mail. Heck if you get a decent amount from it you could grab an LPC sled or other goodies there (or elsewhere) too. The LOC diode from the LPC is a bit trickier to extract but a sharp file or fie tooth metal saw will do the job nicely.

11-30-2010, 11:51 PM #10
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Re: DDL Circuit - Tell me If I'm doin' it right

Quote:
 Originally Posted by LtKernelPanic Check what "As is" broken PS3s are going on ebay or craigslist for. I haven't looked lately but they were selling for about half the price of a new one last I time I checked. If that's still the case or you can get \$50+ I'd probably sell it and go buy a couple PHR sleds from Modwerx Shop. They're a whole 9 bucks each. Shipping will probably be about 5 bucks since they use priority mail. Heck if you get a decent amount from it you could grab an LPC sled or other goodies there (or elsewhere) too. The LOC diode from the LPC is a bit trickier to extract but a sharp file or fie tooth metal saw will do the job nicely.
Okay thanks for the comment and I brought it to my friends house, and we basically took it all apart. Cleaned the dust out, reapplied the thermal paste, and rebuilt it and we still had the results that the kid was having when he gave it to me. So we concluded that it was an error on the motherboard. (Yellow light)

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