Just a thought, it is connected up correctly isn't it? The negative regulators have a different pinout than the positive regulators. IGO for positive and GIO for negative. If connected up wrong, and damaged, can sometimes put out a strange voltage and gets hot. Keep the bypass caps at 0.1uf. Rick >From: fred jones >Hi all, >I thought I'd ask this question here as my pool of friends here can't seem >to offer any help. I have a circuit where I am feeding -24V into a 7905 >linear regulator. It gets very hot, can't keep your finger on it. It is >on >a pretty hefty heatsink. I took the output leg loose and measured the >current draw its supplying and it shows to be 280ma. I would think that it >should not have any problem with this and shouldn't be getting hot. I >thought maybe it was getting so hot because there was such a large voltage >feeding it so I then took the circuit off of the 24v supply and fed it with >12V and again it still gets too hot to touch. I had a .1uf cap on the >input >and output. I looked at the data sheet and from that I tried changing them >out to a 2.2uf on the input and a 1uf on the output. At the same time, I >chaged out the regulator to one of a different brand. Still the same >results. > >My questions would be should it be getting that hot? I thought that it >shouldn't at only 280ma. If not, can you point me toward any problems I >might be having that could cause this? Suggestions of things to look at >would be greatly appreciated. >Thanks, >FJ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.