>Thank you very much for your clear explanation. I have build it and it >seems not to work (some sound is heard but not pure tones) with the 741. Ahh, tones. So it's for sound. The 'classic' 5V sound amp is RC(A)4558 which is an improved 358 version. Peter -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads