On Jun 1, 2012, at 9:24 PM, [email protected] wrote: >> We should test the calibration again. > Walter, Guzman > > Testing with TA140 > > It looks like the 1.75 audio circuit was changed between the preproduction > and the ramp unit 1.75's > > Testing on SKU199 and SKU204, the impedance has gone from 1k to 4k and the > calibration is all wrong on 204 > > (TA calibration should be OK for the moment on preproduction SKU199) > > Can laptop.org please confirm that there was an audio redesign between SKU199 > and SKU204? Is the SKU204 design now stable or can we expect further changes?
Yes, there was a redesign which increased the resistance between the Mic voltage source and the mic jack from roughly 1K to roughly 3K for improved microphone performance. All production XO-1.75s use the SKU204 circuitry. > Is the input protection the same as the 1.5: "The XO-1.5 is protected by a > resistor,(1/16W 470 ohm SMD0402) and a pair of diodes to ground and to +3.3V > which should protect -6V to +9V continuously, and up to higher voltages for > shorter periods of time." > http://wiki.sugarlabs.org/go/Activities/TurtleArt/Using_Turtle_Art_Sensors#Specifications Yes, the protection circuitry is the same as used on 1.5. Chers, wad _______________________________________________ Devel mailing list [email protected] http://lists.laptop.org/listinfo/devel
