rebeltaz 36 Posted April 9, 2014 Share Posted April 9, 2014 Hi, guys... I just wanted to share with you a few pictures of a trainer lab that I built. I have several old Heathkit trainers (hence the color scheme of mine ) but I needed features they didn't offer, so... On a related note, the power supply I am using for this is a converted ATX power supply. The 3.3v line puts out about 3.4v. This should be OK for powering MSP ICs, correct? I was thinking of putting a rectifier in series to drop it down a bit just to be safe, but I wanted to get a second opinion. Rickta59, yosh and bluehash 3 Quote Link to post Share on other sites
wasson65 16 Posted April 9, 2014 Share Posted April 9, 2014 You're well within 10 percent of 3.3, I wouldn't worry at all. Love the trainer, it looks like it would make tinkering around an absolute pleasure. Nicer tools make a difference... Did you route the USB through the trainer or will the host connect normally to the launchpad? Quote Link to post Share on other sites
rebeltaz 36 Posted April 9, 2014 Author Share Posted April 9, 2014 Thanks, I thought so, but I wanted to be sure. Right now, I'm just going to connect to the launchpad like normal, but I am planning on running the USB out the back later on. Quote Link to post Share on other sites
rockets4kids 204 Posted April 9, 2014 Share Posted April 9, 2014 If you don't add current limiting to a PC power supply you *will* regret it at the worst possible time. The simplest way to do this is to regulate the 5V rail down to your desired voltage with a linear regulator that does current limiting such as the LM1117. bluehash and GeekDoc 2 Quote Link to post Share on other sites
bluehash 1,581 Posted April 9, 2014 Share Posted April 9, 2014 @@rebeltaz Very nice! Take R4K's advice on current limiting. Quote Link to post Share on other sites
rebeltaz 36 Posted April 9, 2014 Author Share Posted April 9, 2014 Really? I can do that, but I would have thought that a power supply designed for a computer would be safe.. No problem, I would much rather be safe than sorry Quote Link to post Share on other sites
wasson65 16 Posted April 9, 2014 Share Posted April 9, 2014 What they are getting at is that the power supply will happily and safely supply 3.4 volts at waaaay more amps that it would take to melt wires if something gets shorted on the breadboard. A simple 2 to 5 amp fuse inline with the 3.4 volts would also do the trick I'd think. Quote Link to post Share on other sites
rockets4kids 204 Posted April 10, 2014 Share Posted April 10, 2014 It is not uncommon for recent ATX power supplies to be capable of 30 amps or more on the 3V rail, and even older ones were capable of 15 amps. 15 - 30 amps through a short circuit will make for quite a bang, and if that short happens to be through silicon, well, I hope you are wearing safety glasses. Quote Link to post Share on other sites
tingo 22 Posted April 14, 2014 Share Posted April 14, 2014 @@rebeltaz : that's a nice trainer. It looks great - very well done! Quote Link to post Share on other sites
cde 334 Posted April 16, 2014 Share Posted April 16, 2014 Just as a FYI, the Launchpad runs the msp430 at 3.5~3.6V. That is the recommended maximum, not 3.3V. And most of the time, you can push it a little more, if you are willing to risk going past the Absolute Max ratings. A quick google shows one guy pushing it to 4.2V. Quote Link to post Share on other sites
rebeltaz 36 Posted April 16, 2014 Author Share Posted April 16, 2014 Yeah, I did see that (3.6v) in the datasheet, but I have seen way too many components destroyed (or prematurely failed) because of pushing the too close to the limits. Quote Link to post Share on other sites
Druzyek 36 Posted April 16, 2014 Share Posted April 16, 2014 I think the datasheet lists 4.0v as the absolute maximum. I have no experience but I have heard that it might fail if you run it continuously at that voltage. I don't think 3.6v would shorten its life any more than 3.3v would though. Quote Link to post Share on other sites
abecedarian 330 Posted April 16, 2014 Share Posted April 16, 2014 Datasheet says 4.1V absolute maximum. My R1.5 G2 LPs run at 3.54 and 3.56 volts, unless the DVM is lying to me. Quote Link to post Share on other sites
rockets4kids 204 Posted April 16, 2014 Share Posted April 16, 2014 What does your meter read against a reference source? More than likely you have some resistance in your cables and connectors. Quote Link to post Share on other sites
abecedarian 330 Posted April 20, 2014 Share Posted April 20, 2014 Do you have, or are you willing to post, schematics for this? I could probably find them somewhere but having something from someone familiar is a plus. Quote Link to post Share on other sites
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