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Old 5th August 2005, 02:47 AM   #11
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Thank you guys for all your help. After doing some reading it seems the lower you make the output voltage the hotter this little regulator is going to run. So if I am using a 28v supply and only need 5v from it, the LM317 has to dissipate the other 23v as heat .

In conclusion, I think I will use a LM350 or LM338, as they are rated at 3 and 5 amps. Thanks again for the help fellas.
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Old 5th August 2005, 05:44 AM   #12
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Default Heat problem

With only .08a max the dissipation would be .08 X 23 = 1.84W. A small L bracket used to mount the part to the case would do very well getting rid of the heat This is very comfortably within the LM317ís specs, no problem. You really donít need to use something bigger, especially something optimized for higher currents.
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Old 5th August 2005, 07:19 AM   #13
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Lots of SMPS have more than one power output. It's possible to use one of those and then regulate it. 5V is very common in SMPSs as well, I just don't know how accurate they are.
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Old 5th August 2005, 12:21 PM   #14
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Your right Roger, I misread something in the document that led me to believe it would get much warmer than 1.6 watts of dissipation.

I'm using four 14v 12 amp supplies in series and there is no 5v section. Maybe theres 5v on the board somewhere, but I'm not comfortable probing around to find out.

I think this will work out well as long as I don't blow anything up trying to get the LM317 circuit working, I'm uber novice.

I'm just going to order one AMP1 for now and see how assembly goes and if I can actually get it to work. It will end up costing me another $10 in shipping fees to break up the order like that, but its better than having two more kits I can't use if things don't turn out right.
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Old 5th August 2005, 12:49 PM   #15
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Ok, another question . Tripaths circuit has the ground and Vin reversed from the standard LM317 circuit because it uses VNN which would make ground positive for the 5v supply.

That doesn't sound very safe for how I intend to use it. Would it be ok to use VPP instead and use the standard LM317 input scheme?

Attached is an image of both circuits with tripaths being on top.
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Old 5th August 2005, 02:11 PM   #16
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Quote:
Originally posted by theAnonymous1
Would it be ok to use VPP instead and use the standard LM317 input scheme?
yes. the tripath circuit is like that so the voltage is referenced to the negative supply rail. plus, that was a schematic for an external V10 supply.
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Old 5th August 2005, 02:39 PM   #17
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Seems I let my anxieties get the best of me again, the answer was as simple as just taking a moment to look at the 41hz website with my eyes a little wider open .
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Old 5th August 2005, 03:17 PM   #18
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Quote:
Originally posted by theAnonymous1
Seems I let my anxieties get the best of me again, the answer was as simple as just taking a moment to look at the 41hz website with my eyes a little wider open .
Little devices like the attached pic can help you get rid of the transformer. If you get a 7.5V or 9V one and use it with an LM7805, it's very small.
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Old 5th August 2005, 04:15 PM   #19
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soongsc, I'm going to use an SMPS, so in the pic just imagine everything to the left of the +/- 30v gone and replaced with it.

I really need to slow down a bit, I just ordered 6 LM317's off ebay, then I found some LM317LZ's which are a TO-92 package that handle 100ma that I thought would work perfectly. This was all before I saw the 7805 regulator circuit on 41hz.com, so after seeing it I bought 6 LM7805's.

Now, I'm sure your saying something like "did this guy forget to take his meds today", but its not over yet. After ordering the 7805's I remembered I had some regulators somewhere but I had no clue what they were. I found four of them after a short search and low and behold their some nice Motorola T7805CT's that I verified to work in about 30 seconds hooking it up with two jumper wires to an SLA.

So after all my rambling and questions the answer to my problem was as close as the website for the amp, and my own junk drawer .
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Old 5th August 2005, 05:09 PM   #20
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Quote:
Originally posted by theAnonymous1
soongsc, I'm going to use an SMPS, so in the pic just imagine everything to the left of the +/- 30v gone and replaced with it.

I really need to slow down a bit, I just ordered 6 LM317's off ebay, then I found some LM317LZ's which are a TO-92 package that handle 100ma that I thought would work perfectly. This was all before I saw the 7805 regulator circuit on 41hz.com, so after seeing it I bought 6 LM7805's.

Now, I'm sure your saying something like "did this guy forget to take his meds today", but its not over yet. After ordering the 7805's I remembered I had some regulators somewhere but I had no clue what they were. I found four of them after a short search and low and behold their some nice Motorola T7805CT's that I verified to work in about 30 seconds hooking it up with two jumper wires to an SLA.

So after all my rambling and questions the answer to my problem was as close as the website for the amp, and my own junk drawer .
I think we're on the same boat. I have an AMP2 that's supposed to come in soon, and I just got two 48V SMPSs that I intend to put in series (two of these turned out more expensive than the kit itself. ). I'm also trying to figure out what to do to get the 5V. Most SMPS that I looked at had that kind of output, but not with the one's I got. So I'm just going to get the little AC-DC power either the 7.5V one or the 9V one and hook the LM7805 to regulate it. All I need to do is check the max input voltage of the LM7805.
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