Guest marr Posted August 2, 2004 Report Share Posted August 2, 2004 What happens if my powersupply doesn't give enough mA?I have a 9VDC/500mA and I'm starting to wonder if that's enough to run everything on the SEQ, with the two backlit 40x2 LCD etc... Should I start off with the pot for the LCD lighting all the way off and work up from there or what?Am I running a risk of irritating (permanently) the PIC or LCD controllers or anything like that? Quote Link to comment Share on other sites More sharing options...
Guest marr Posted August 2, 2004 Report Share Posted August 2, 2004 What happens if my powersupply doesn't give enough mA?I have a 9VDC/500mA and I'm starting to wonder if that's enough to run everything on the SEQ, with the two backlit 40x2 LCD etc... Should I start off with the pot for the LCD lighting all the way off and work up from there or what?Am I running a risk of irritating (permanently) the PIC or LCD controllers or anything like that? Quote Link to comment Share on other sites More sharing options...
Guest kostix Posted August 3, 2004 Report Share Posted August 3, 2004 I would start from 1A and on the powerfullier ur supply is, the better the equipment wont take more than it needs, so whats better than giving it virtually "limitless" supply and let it take how much it wants :) Quote Link to comment Share on other sites More sharing options...
Guest kostix Posted August 3, 2004 Report Share Posted August 3, 2004 I would start from 1A and on the powerfullier ur supply is, the better the equipment wont take more than it needs, so whats better than giving it virtually "limitless" supply and let it take how much it wants :) Quote Link to comment Share on other sites More sharing options...
moebius Posted August 3, 2004 Report Share Posted August 3, 2004 Hi,I think that doc would be better to answer this, but anyway:If your regulator can't supply enough power to the circuit, it overheats - and thermal protection kicks in, it starts to limit current, by droping output voltage. (remember your U/R=I)This probably leads to strange behaviour, random resets ect.If your transformer is underrated, then everything might seem like normal, as regulator can suck enough power out of it anyway, BUT transformer heats up, let's say more than in normal use.. (Or it might even have a fuse that blows.. but usually no thermal protection.) This shortens expected "life" of the transformer and in extreme cases can lead to fire hazard..Bye, Moebius Quote Link to comment Share on other sites More sharing options...
moebius Posted August 3, 2004 Report Share Posted August 3, 2004 Hi,I think that doc would be better to answer this, but anyway:If your regulator can't supply enough power to the circuit, it overheats - and thermal protection kicks in, it starts to limit current, by droping output voltage. (remember your U/R=I)This probably leads to strange behaviour, random resets ect.If your transformer is underrated, then everything might seem like normal, as regulator can suck enough power out of it anyway, BUT transformer heats up, let's say more than in normal use.. (Or it might even have a fuse that blows.. but usually no thermal protection.) This shortens expected "life" of the transformer and in extreme cases can lead to fire hazard..Bye, Moebius Quote Link to comment Share on other sites More sharing options...
pay_c Posted August 3, 2004 Report Share Posted August 3, 2004 Counting the Seq:2x LCD backlight appr. at 200 mA = 400 mAThe whole schematic (including core, DIN´s, DOUT´s): about 50 mA - 100 mALEDs: from 0 up to more than 300 mA (!!)So with the Seq you´re some good kinda over the 500 mA.Greetz. Quote Link to comment Share on other sites More sharing options...
pay_c Posted August 3, 2004 Report Share Posted August 3, 2004 Counting the Seq:2x LCD backlight appr. at 200 mA = 400 mAThe whole schematic (including core, DIN´s, DOUT´s): about 50 mA - 100 mALEDs: from 0 up to more than 300 mA (!!)So with the Seq you´re some good kinda over the 500 mA.Greetz. Quote Link to comment Share on other sites More sharing options...
doc Posted August 3, 2004 Report Share Posted August 3, 2004 Start with 1A min.500mA doesn't make sense in your case !greets Doc Quote Link to comment Share on other sites More sharing options...
doc Posted August 3, 2004 Report Share Posted August 3, 2004 Start with 1A min.500mA doesn't make sense in your case !greets Doc Quote Link to comment Share on other sites More sharing options...
Guest marr Posted August 3, 2004 Report Share Posted August 3, 2004 Thanks all for confirming my suspicions.. I suppose now I might need to look into getting a bigger heatsink for the 7805. Quote Link to comment Share on other sites More sharing options...
Guest marr Posted August 3, 2004 Report Share Posted August 3, 2004 Thanks all for confirming my suspicions.. I suppose now I might need to look into getting a bigger heatsink for the 7805. Quote Link to comment Share on other sites More sharing options...
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