audioguru Posted August 4, 2010 Report Share Posted August 4, 2010 Hi Bean,The original project had many errors so it did not produce 30VDC at 3A but instead produced about only 25VDC with lots of ripple at 3A.Many of its parts overheated especially the old fashioned and tiny transistor Q2 and the transformer.The unregulated supply was a total of 40.3V without a load but the opamps in the original project have an absolute max total supply of only 36V.I corrected some of the problems 5 years ago by using OPA445 high voltage opamps, a more powerful Q2 transistor and a few other changes but then this opamp became hard to find and expensive. So the latest version uses two types of opamps that are available almost anywhere, do not need a huge negative supply voltage and have a max total supply of 44V.The datasheet is what you should look at because maybe Farnell missed that the max supply voltage for the TLE2141 is plus and minus 22V which is a total of 44V.The latest version has a small negative supply for U3 and no negative supply for U1 and U2. Most opamps do not work with a small negative supply or no negative supply. The opamps for the latest version were selected because they work perfectly with a small or no negative supply voltage. Quote Link to comment Share on other sites More sharing options...
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