Hi Robert, why does it have to be 10nF specifically? What do those caps do? I have a professional audio mixer circuit here that uses in-line 47uF polarized caps at the signal inputs. Does the accuracy matter? Cheers Ryan On 18 March 2015 at 18:42, Robert Dvoracek wrote: > 10nF, use film caps. > I would have also connected the feedback resistor after the totem pole in= stead of before it to correct for some of the distortion in the final stage= .. > > Cheers, > Robert > > ---------------------------------------- >> From: bobblick@ftml.net >> To: piclist@mit.edu >> Subject: Re: [EE] simple opamp amplifier problems >> Date: Tue, 17 Mar 2015 22:01:18 -0700 >> >> Actually I take back that thing about the third diode, just the pulldown >> resistor should fix things. >> >> Bob >> >> On Tue, Mar 17, 2015, at 09:46 PM, Bob Blick wrote: >>> Hi Ryan, >>> >>> The LM358 will require a pulldown resistor on its output, otherwise it >>> runs class B and will distort real bad. >>> >>> Also you will need to get the bases of your transistors a little furthe= r >>> than 2 diodes apart. Put a third diode in there, and it should sound >>> great but use too much current. Make that third diode a Schottky and yo= u >>> should be golden. >>> >>> Cheerful regards, Bob >>> >>> On Tue, Mar 17, 2015, at 09:36 PM, Ryan O'Connor wrote: >>>> Hi guys, I've bread-boarded the following circuit, but its not playing >>>> audio. I get only DC current at the base of the 2N4401. I've had it >>>> playing audio briefly while screwing around. For example if I remove >>>> the 0.01uF cap from the non-inverting input of the left-most opamp and >>>> plug it back in, I hear a distorted version of the song I am playing >>>> as input for about half a second (actually the cap value is polar >>>> 47uF). Then silence, DC voltage. Could it be because I am using >>>> electrolytics for these two caps? I can't find any "103" bipolar lying >>>> around, or even close to it. I tried a 0.47uF bipolar but I only hear >>>> about 0.05 seconds of audio when I plug/unplug that one. Have double >>>> checked all the wiring twice. >>>> >>>> Circuit below: >>>> >>>> http://www.techlib.com/electronics/graphics/audioa14.gif >>>> >>>> Cheers, >>>> Ryan >> >> -- >> http://www.fastmail.com - Choose from over 50 domains or use your own >> >> -- >> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist > > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .