Guest Kaash Posted August 16, 2013 Report Share Posted August 16, 2013 hi guys..im using 7912 as negative voltage regulator but when i connected it with 12v or 20v supply it got very hot without any output voltage.i wasted 4-5 regulators but get no output -12, is there other any way to connect it?help plz.thanks Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 17, 2013 Report Share Posted August 17, 2013 Why didn't you look at the datasheet for the 7912??It shows an input capacitor and an output capacitor that prevent it from oscillating at a high frequency which causes heating.The voltage from its input to output TIMES its load current sets how much dissipation (heating) it makes when the capacitors are there.Is it mounted on a finned heatsink with thermal grease? That is how to cool it. Quote Link to comment Share on other sites More sharing options...
Hero999 Posted August 17, 2013 Report Share Posted August 17, 2013 You connected it up backwards so that was going to happen. It's a negative regulator, thus its input voltage should be negative but you gave it postive 12V and fried it. Quote Link to comment Share on other sites More sharing options...
audioguru Posted August 17, 2013 Report Share Posted August 17, 2013 Hee, hee.I did not notice that the supply polarity was backwards. Quote Link to comment Share on other sites More sharing options...
Guest Jibby Posted October 3, 2013 Report Share Posted October 3, 2013 Wrong use resulted in damage of 7912.Check the connections as per the data sheet Quote Link to comment Share on other sites More sharing options...
Hero999 Posted October 3, 2013 Report Share Posted October 3, 2013 Hee, hee.I did not notice that the supply polarity was backwards.Lol what amused me is he wasted 5 regulators without realising there was a problem with the circuit.The lesson is, if it gets hot and components smoke, check there's nothing wrong with the circuit before replacing them and trying again.Here's how to do it correctly. Quote Link to comment Share on other sites More sharing options...
Muhammad shafiq Posted November 26, 2019 Report Share Posted November 26, 2019 On 8/17/2013 at 1:39 AM, Guest Kaash said: hi guys.. im using 7912 as negative voltage regulator but when i connected it with 12v or 20v supply it got very hot without any output voltage. i wasted 4-5 regulators but get no output -12, is there other any way to connect it? help plz. thanks Hi please confirm connection probe becauce your connection same like voltage regulator 78.. Quote Link to comment Share on other sites More sharing options...
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