Wednesday, May 19, 2010

Chapter 5 - Exercise 29 part 3

Okay, I'm still having trouble with experiment 29. I'm including some close-up photos here, hoping that someone may catch an error or see something that I'm not doing properly.

A few things - the schematic on page 251 (Figure 5-41) shows the hookup wire and the 10 microfarad components wired up in series but with a set of pushbuttons used to isolate them. I thought this might be the issue early on so you'll see that I've only got the hookup wire in the circuit... I figure if I can get the sound working with the hookup wire, then I'll pull it out and insert the capacitor.

Other than that, I believe I've wired up the circuit as seen in Fig 5-41. I've verified all my capacitors and resistors for their values... the TEA2025B chip is inserted with the proper orientation... and I've got the 100 microfarad smoothing capacitor between the voltage inputs. The headphone jack is the only other questionable issue that I'm not sure how to test... I taped the wire inserted into the one socket as well as the one connected to the outer metal surface of the other socket...

One question, though - I used solid core 22 gauge wire for the speaker. I'm wondering if that wire is too "heavy" for this experiment.

Any advice is welcome... I'm not wanting to get bogged down on this experiment but experiment 30 builds on it... so if I can't get it working soon, I'll have to skip 30 and jump to experiment 31. If anyone has successfully completed this experiment with solid results, please let me know, as well. If I can't get it working, I'd at least like to get a video of an actual working project.


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  2. Jim:

    I think I see a mistake in your circuit. Looking at the center picture, it appears that you have the 100uF electrolytic cap hooked up to pin 10, and nothing hooked up to pin 11. That cap should be on pin 11.

    I have built this circuit and it works great! The sound quality is way better than I expected.

    ~ Russ