Nick, Would replacing the 7805 with a 'non-isolated dc/dc converter' like Jon suggested solve the problem too? I ask because I was going to try the Traco TSR 1-2450, or the Murata part (though I'm not sure it will fit.) I ordered both.
I'll get my scope out today and see what I can see. Kiran On Monday, March 30, 2015 at 6:33:57 AM UTC-4, Nick wrote: > > Just to re-iterate - solder a small 100nF capacitor between pins 1 & 2, > and another between pins 3 & 2, preferably on the underside of the PCB > directly to the 7805's solder pads. > > The symptoms you are seeing are almost certainly nothing to do with the > heatsinks etc - I'd put good money on this being a very common & classic > issue with 78xx & 79xx linear regulators whereby they break into VHF > oscillation and over-heat. This is extremely well documented and the > manufacturer's datasheets all say that the two suppression caps are not a > "nice to have" but are essential. Most of the datasheets actually specify a > 330nF input capacitor (between pins 1 & 2) but a 100nF works well too. > > Missing out these two capacitors is a basic error. > > Nick > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/b4012849-acd5-4630-ad73-62ea6ee8c803%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
