With no input signal, what voltage do you read between the two 4.7 ohm resistors? On Mar 18, 2015 12:33 AM, "Ryan O'Connor" wrote: > Hi Bob thanks for the reply. I added a couple of 180K pull-down > resistors after each output, but it made no difference. Still no audio > happening unless I pull the cap out and put it back in after a few > seconds. Or I turn off my power supply and I hear audio for a brief > moment as the caps drop their voltage. The output I hear is still very > distorted. It's a published circuit so I'm expecting it to work as-is. > Trying to debug the problem really... > > On 18 March 2015 at 18:01, Bob Blick wrote: > > Actually I take back that thing about the third diode, just the pulldow= n > > 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 furth= er > >> 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 y= ou > >> 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 playi= ng > >> > 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 a= nd > >> > 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 lyi= ng > >> > around, or even close to it. I tried a 0.47uF bipolar but I only hea= r > >> > 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 .