SugarAddict 227 Posted October 20, 2012 Share Posted October 20, 2012 ow duck that hurt... yes... the 34063 gets HOT Quote Link to post Share on other sites
cubeberg 540 Posted October 21, 2012 Author Share Posted October 21, 2012 I think I might have figured it out. What are the color codes on the inductor? Quote Link to post Share on other sites
bluehash 1,581 Posted October 21, 2012 Share Posted October 21, 2012 blue/(yellow/gold?)/back/silver Quote Link to post Share on other sites
cubeberg 540 Posted October 21, 2012 Author Share Posted October 21, 2012 Actually - now that I look at it - it might be the size of the inductor. The color codes are the same, but the physical size is completely different. Here's a side-by-side comparison: If the inductor isn't large enough and is saturating, I'm guessing that's leading to the overheating. When I get my kit - I'll try swapping the inductor. bluehash and pbirkel 2 Quote Link to post Share on other sites
cubeberg 540 Posted October 22, 2012 Author Share Posted October 22, 2012 Well, the inductors are definitely completely different specs. The markings indicate 68uh as expected, but they're physically a different size. I'm working with the vendor to see if we can resolve the problem. I'll be testing tonight. Quote Link to post Share on other sites
cubeberg 540 Posted October 23, 2012 Author Share Posted October 23, 2012 Yep - it's the inductor. I tried with the smaller inductor and was able to get a pretty good stink off of the boost chip after a couple of seconds when I turned up the trim-pots just a bit (~35v). Putting in one of the inductors I got in an earlier batch of parts - the device runs nice and cool even when turned up all the way (over 50V). I've already contacted Tayda about the parts (including the buttons as well). Worst case - we can source axial inductors from someplace else. Does someone have a way of measuring inductance to see if they are indeed 68uH? I'm wondering if it's the inductance that's wrong, or some other characteristic of the part. If someone does - let me know. I could send someone the larger inductor for testing as well. Quote Link to post Share on other sites
SugarAddict 227 Posted October 23, 2012 Share Posted October 23, 2012 They are probably both 68uH but different current maximums, would be my guess. cubeberg 1 Quote Link to post Share on other sites
pbirkel 1 Posted October 24, 2012 Share Posted October 24, 2012 Compare to http://www.mouser.com/ProductDetail/Fas ... dGbnszs%3d (and similar) at Mouser. This 49 mA part is dimensioned as 6 mm Dia. x 16 mm L. ($0.86 @, BTW) Compare to http://www.mouser.com/ProductDetail/Bou ... u9ljAt0%3d at Mouser, a 24 mA part dimensioned as 0.45 in L (~11 mm in L). ($1.26 @, BTW) viperspd 1 Quote Link to post Share on other sites
LariSan 81 Posted October 25, 2012 Share Posted October 25, 2012 Not sure if this helps at all in the trouble shooting , but I replaced my inductor on mine with another 68uH inductor (here) 2012-10-25 13.48.39 by laraswanland, on Flickr to verify code: http://www.learnabout-electronics.org/a ... tors04.php it still got hot, just much slower. are we sure it's just the inductor?] Quote Link to post Share on other sites
cubeberg 540 Posted October 25, 2012 Author Share Posted October 25, 2012 LariSan - do you have a datasheet? I'd be interested in the current limits (looks like you meant to include a link). Also - if you turn down your pots all the way (you've got them at half) to reduce current to a minimum - does it stay cool? This would reduce the current requirements. I'm still waiting on the v1.1 PCB to validate that it's not the PCB either, but I have built a boost circuit with a full set of the latest batch of parts. Since you seem to be able to run your board for a bit without burning up - what current rating are you getting on the banded side of the schottky (nearest to the capacitors)? Quote Link to post Share on other sites
oPossum 1,083 Posted October 25, 2012 Share Posted October 25, 2012 The inductors pictured in this thread are the style that is typically use for a RF choke coil. The style typically used in a small SMPS is like this A large ferrite core is need to handle the peak switch currents in a SMPS. It will typically be bobbin or toroid shape. Quote Link to post Share on other sites
oPossum 1,083 Posted October 25, 2012 Share Posted October 25, 2012 Does someone have a way of measuring inductance to see if they are indeed 68uH? I'm wondering if it's the inductance that's wrong, or some other characteristic of the part. If someone does - let me know. I could send someone the larger inductor for testing as well. I have an Agilent LCR meter. You are welcome to send anything to me for testing. I can confirm the uH rating, Q and some other specs. I don't have a way to measure saturation current - and I think that is the problem causing the MC34063 to get hot. Quote Link to post Share on other sites
cubeberg 540 Posted October 25, 2012 Author Share Posted October 25, 2012 oPossum - I can certainly send you a couple to test out - can you PM me your address? Do you have any inductors on hand to test on the board as well? Anything above 68uH with a decent current limit should work for testing on the board. Quote Link to post Share on other sites
gordon 229 Posted October 25, 2012 Share Posted October 25, 2012 Thread got me interested, and here's something that I bumped across, might be useful to your application as well: Theory and Applications of the MC34063 and Quote Link to post Share on other sites
LariSan 81 Posted October 26, 2012 Share Posted October 26, 2012 Hi Cube, Sadly, I got it from the resale store (Tanner Electronics) and they couldn't find the data sheet. I only attached the colour code reading guide. I did try it with both of the pots turned way down and it's the same. It delays, but still gets hot. I'm not near any equiptment today, so I wasn't able to test it out. I'll make sure to do it when I get home and will get back to you! Not sure if it helps, but I poked around the data sheet and came across something that could be interesting. The sample schematic for this part: http://www.ti.com/tool/pmp7006 (no idea why it's not included in the part's datasheet). looks a little bit different from the board schematic. pmp7006 schematic by laraswanland, on Flickr [tipdf]slls636m[/tipdf] boosterpack schematic by laraswanland, on Flickr Could that possibly be the issue? Quote Link to post Share on other sites
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