huangyong 0 Report post Posted October 6, 2004 (edited) Had completed a +/- 15V Power Supply, using LM7915/7815. now thinking of DIY an AC powered small amp. I have tried Cmoy, CH47, "PoorMen" PPA and other opamp based amp. Now i want to try something different, perhaps a discrete amp?? might be too diffifcult for me.. after checking my component box, I have 2 opa627, 2 op27, 2 IRF510 MOSFET and assorted resistors/caps from my previous projects. I need to spend as little as possible yet fully utilise the unused parts. So, i am think of making an Opamp+MOSFET amp in Class A mode, with a DC servo so that can eliminate caps in signal path (save cost too ) Some pics: Links: Szekers Amp Szekers The question is how to combine the uniqueness of 3 of them?? Edited October 6, 2004 by huangyong Share this post Link to post Share on other sites
bpribadi 0 Report post Posted October 6, 2004 (edited) with a DC servo so that can eliminate caps in signal path Are you sure??? I see caps along the audio line You can try this one: http://headwize.com/projects/stokes_prj.htm But need a match pair for your mosfet. Edited October 6, 2004 by bpribadi Share this post Link to post Share on other sites
huangyong 0 Report post Posted October 6, 2004 Bripadi, The MOSFETs used in SDS amp are quite difficult to get, and they need to be matched. My concept comes from here LC-king The cap C1 can be eliminated and the entire signal path is capless. ( i have tried this mod on voxel's LC-King Before) so i guess i can use the same concept, with opamp + discrete buffer (MOSFET) and then with the DC servo. now my question is how to use DC servo correctly? Share this post Link to post Share on other sites
jasonhanjk 0 Report post Posted October 6, 2004 LC-king very famous among Taiwan DIYers... Another DC servo amp that I know is the Gilmore, too bad it is an AB. Sorry can't help you. Share this post Link to post Share on other sites
huangyong 0 Report post Posted October 7, 2004 Found a useful layout pic of SDS amp. Share this post Link to post Share on other sites
heady 0 Report post Posted October 7, 2004 (edited) Anyone care to explain what purpose the LEDs serve in the SDS schematic? In layperson english if possible. And huangyong, do you have the list of parts that goes with this? I have heard good things about the SDS amp. Thanks. Edited October 7, 2004 by heady Share this post Link to post Share on other sites
bpribadi 0 Report post Posted October 7, 2004 Hi Heady, the LEDs are to bias the transistors. Share this post Link to post Share on other sites
heady 0 Report post Posted October 7, 2004 Hi Bram, transistors used to bias op-amps. LEDs to bias transistors. Giddy already. Never mind, if some expert builts it and share how, then can try. Share this post Link to post Share on other sites
