Where can you salvage a LM317?

I was wondering if anyone knew any common electronic gadgets/appliances that commonly used the LM317 voltage/current regulator?

My local radio shack locations are really poor about keeping components in stock and as is the case everywhere, they are mostly a cell phone store now. I will probably end up ordering 10 or so from Digikey/Mouser, but for right now, I'd like to just take apart something like an old PC power supply and find a nice regulator that I could use to push something like 1.5a or more through a pump diode...or at least one amp.

-Brett

Here's one place that you can get them new for relatively cheap.  I've ordered from Newark three times and have never been charged shipping.  They also know how to properly package the components they send.

They also have the LM317 available in a non-TO220 design, but that's probably for lower-current applications.

I've found a lot of 1117T's inside of DVD burners... They're related to the 317 only they have a lower dropout voltage. About half of the burners I take apart have them, some even have more than one.. IIRC they're only rated for an amp though.

pseudolobster said:

I've found a lot of 1117T's inside of DVD burners... They're related to the 317 only they have a lower dropout voltage. About half of the burners I take apart have them, some even have more than one.. IIRC they're only rated for an amp though.

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Thanks. Are the 1117's you found there surface mount, or leaded? I don't mind soldering surface mount, I'm just asking to make finding them easier.

-Brett

If you're in the US, I can send you three (3) via regular mail (1.5A versions).  I bought 50 of them on eBay for some amount, and will never get through them all.

pseudolobster said:

I've found a lot of 1117T's inside of DVD burners... They're related to the 317 only they have a lower dropout voltage. About half of the burners I take apart have them, some even have more than one.. IIRC they're only rated for an amp though.

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I saw a 1117 in a Lite-On burner I took apart recently , but I couldn't desolder it for the life of me!  There was a similar component sitting right by it, but I couldn't remove either .

Bionic-Badger said:

If you're in the US, I can send you three (3) via regular mail (1.5A versions).  I bought 50 of them on eBay for some amount, and will never get through them all.

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PM sent!

Phoenix3200,

Do you have any pics of the part? Do you know what standard package it was?

-Brett

The 1117 is surface mount.  This is what the package shape looks like:



A number of the drivers around here (like the Groove you can get from DrLava) use the 1117.

phoenix3200 said:

The 1117 is surface mount.  This is what the package shape looks like:

A number of the drivers around here (like the Groove you can get from DrLava) use the 1117.

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Very cool. Can you give me a link or thread name for DrLava's "Groove" driver? I wonder if there is a .pdf for it? It would be nice to have an idea of how to populate the 1117t when I do find it. Until then I will look up the datasheet. Thanks!

-Brett

phoenix3200 said:

The 1117 is surface mount.  This is what the package shape looks like:

A number of the drivers around here (like the Groove you can get from DrLava) use the 1117.

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While I've certainly seen those, most of the 1117's I've found have been TO-252 surface mount...

They look like this:


As for reusing the schematic for the groove driver, don't bother.. it's sorta strangely made.. It uses a precision voltage reference diode for some reason...

I've been making my 1117 drivers using this schematic phenol posted: http://www.laserpointerforums.com/forums/YaBB.pl?num=1216777150/... though there's really nothing different between the 317t and the 1117t, you can drop a 1117t into daedal's circuit and it'll work acceptably. Rkcstr's driver also uses the 1117.. It's basically just a fancy DDL driver when you look at it.

Cool, I am going to read that whole thread about phenol's driver as soon as I am done writing this.  You guys have all been very helpful.  Perhaps this thread will help out other people as well, who are struggling to build these different drivers.  I've been wanting to build my own ever since I read Daedal's tutorial on the LM317 based driver.  I have *some* electronics experience, but I'm not a professional engineer, so I'm bound to screw up every now and then.  

Just a minute ago I took apart an old analog cell phone charger I had sitting around.  I found these Motorola parts, which appear to be what I am looking for.  Can anyone shed any light?  The Datasheet Archive page I usually use is lagging right now:

*edit* well...checked the data sheet (the one from Fairchild anyway...not Mot.) and it looks like I have a couple of winners. Now as long as I didn't heat them up too much in the desoldering process.

pseudolobster said:

Rkcstr's driver also uses the 1117.. It's basically just a fancy DDL driver when you look at it.

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Hey now, I resent that!  

Technically, the "Daedal" criver it isn't really Daedal's design either (just some add-ins like the output protection diode, selection of pot/resistor values and not using an input cap are his)... its a standard configuration outlined in the datasheet of most 3 pin adjustable regulator ICs.  However, the details are what make the circuit what it is. There's a lot of work in choosing the right parts, values and designing the layout and other subtleties that may go overlooked by others.

Also, the groove driver does something "different".  The regular circuit basically works by measuring the voltage across the current setting resistor and adjusting the current until it matches the 1.25V reference in the chip.  The "Groove" and also the "Fusiondrive" use an external voltage reference with a divide to adjust the voltage going to the adjustment pin of the IC depending on current, basically "tricking" it into thinking it is measuring 1.25V across the resistor when it is just getting a feedback voltage from the external reference.  The IC adjusts the current until the external reference puts out enough voltage, so it doesn't work the same as the "usual" circuit and values aren't quite as easy to figure out.

Anyway, the pictures you (the OP) show above are LM317T and should work for your needs.

rkcstr said:

Anyway, the pictures you (the OP) show above are LM317T and should work for your needs.

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rckstr,

Thank you for explaining about the different driver topologies, that's why I am here...to learn exactly these things (and more).

The LM317T certainly is working. Since I posted last, I have put together a similar driver to the one popularized in Daedel's tutorial. The picture shows it operating without such a reference resistor, this was simply because I did not have a low value resistor on hand, and also I don't currently have a 100 Ohm pot, so I used a 25 Ohm from my junk box. I have a good start to try different component values in before I (carefully) eventually try a laser diode with it. I'd like to thank everyone who helped me get this going so rapidly!

^Looking good!!

Thanks ElektroFreak!  

I need to devise a dummy load that will simulate the characteristics of 500/1000mw C-mount pump diodes.  Should I just find the datasheets and use Ohm's law, or are there other things to consider?

Mostly what I've seen about these DIY drivers has been about testing them for eventual use with reds and blu-ray diodes.  Very cool, but I want to drive small DPSS with this.  Any threads I should know about?

-Brett

Brett Miller said:

Thanks ElektroFreak!  

I need to devise a dummy load that will simulate the characteristics of 500/1000mw C-mount pump diodes.  Should I just find the datasheets and use Ohm's law, or are there other things to consider?

Mostly what I've seen about these DIY drivers has been about testing them for eventual use with reds and blu-ray diodes.  Very cool, but I want to drive small DPSS with this.  Any threads I should know about?

-Brett

Click to expand...

You're trying to simulate the forward voltage of the diode in question, which should be about 2v... 3 of them should do it. Make sure your diodes are capable of handling that sort of amperage though.