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February 23, 2007
about 3 years ago
I was having the same problem as everyone else: the ~5Hz thumping sound.
I thought there was no way it could be due to a noisy power supply since I’m running it straight off of a car battery (charged by solar panels). I was wrong.
The onboard 1000µF bypass capacitor on the power input is really totally insufficient for this amplifier to remain stable. I added another 10000µF (probably overkill) just before the power-in to the board (with a Schottky diode on the battery side) and now everything is running great. Also added a pair of 0.1µF mylar caps on the input lines to remove some of the excessive bass (since I live in an apartment). Some sort of eq. would have been nice instead of an extra volume knob…
Other than the couple of small design issues, this amp is great and was really fun to build. It’s insanely loud, even driving 8ohm speakers from only a ~12-13V supply, I have to keep the volume knobs at about ¼ in order not to feel like a bad neighbour (although I sometimes see the ‘peak’ light flicker for very brief moments, even at this level – but only so much that can be done with using a 12V supply to drive 8ohm speakers).
Finally time to decommission my dad’s old 1970s Kenwood… a sad day. :(
about 5 years ago
I am in physical possession of one of these panels, and the datasheet at http://sharesend.com/cm096 doesn’t seem to be accurate. Both the electrical characteristics and physical appearance are much closer to what’s listed here in the product description (although I’ve seen the completely unloaded open-circuit voltage get as high as 12V).
According to a Sparkfun employee on IRC this panel is a custom-made part for SFE by a company called NingBo Evergreen Plastic Factory (http://www.appolloo.cn/). Because of that, I wouldn’t be surprised if there is no datasheet at all…
ps: I bought mine from a SFE distributor in Toronto and it came with a ~2m red and black stranded power cord with a barrel plug on the end (that fits nicely into the Arduino, for example).
No public wish lists :(
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